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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Kernel Probes (KProbes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2002, 2004
19 *
20 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
21 * Probes initial implementation ( includes contributions from
22 * Rusty Russell).
23 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
24 * interface to access function arguments.
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010025 * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
26 * <prasanna@in.ibm.com> adapted for x86_64 from i386.
Linus Torvalds1da177e2005-04-16 15:20:36 -070027 * 2005-Mar Roland McGrath <roland@redhat.com>
28 * Fixed to handle %rip-relative addressing mode correctly.
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010029 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
30 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
31 * <prasanna@in.ibm.com> added function-return probes.
32 * 2005-May Rusty Lynch <rusty.lynch@intel.com>
33 * Added function return probes functionality
34 * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
35 * kprobe-booster and kretprobe-booster for i386.
Masami Hiramatsuda07ab02008-01-30 13:31:21 +010036 * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
37 * and kretprobe-booster for x86-64
Masami Hiramatsud6be29b2008-01-30 13:31:21 +010038 * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
39 * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
40 * unified x86 kprobes code.
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 */
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <linux/kprobes.h>
44#include <linux/ptrace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/string.h>
46#include <linux/slab.h>
Quentin Barnesb506a9d2008-01-30 13:32:32 +010047#include <linux/hardirq.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <linux/preempt.h>
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -080049#include <linux/module.h>
Christoph Hellwig1eeb66a2007-05-08 00:27:03 -070050#include <linux/kdebug.h>
Masami Hiramatsub46b3d72009-08-13 16:34:28 -040051#include <linux/kallsyms.h>
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -050052#include <linux/ftrace.h>
Ananth N Mavinakayanahalli9ec4b1f2005-06-27 15:17:01 -070053
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +010054#include <asm/cacheflush.h>
55#include <asm/desc.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070056#include <asm/pgtable.h>
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -080057#include <asm/uaccess.h>
Andi Kleen19d36cc2007-07-22 11:12:31 +020058#include <asm/alternative.h>
Masami Hiramatsub46b3d72009-08-13 16:34:28 -040059#include <asm/insn.h>
K.Prasad62edab92009-06-01 23:47:06 +053060#include <asm/debugreg.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
Linus Torvalds1da177e2005-04-16 15:20:36 -070062void jprobe_return_end(void);
63
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -080064DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
65DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
H. Peter Anvin98272ed2009-10-12 14:14:10 -070067#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +010068
69#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
70 (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
71 (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
72 (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
73 (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
74 << (row % 32))
75 /*
76 * Undefined/reserved opcodes, conditional jump, Opcode Extension
77 * Groups, and some special opcodes can not boost.
78 */
79static const u32 twobyte_is_boostable[256 / 32] = {
80 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
81 /* ---------------------------------------------- */
82 W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */
83 W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */
84 W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */
85 W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
86 W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
87 W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */
88 W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */
89 W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
90 W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */
91 W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
92 W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */
93 W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */
94 W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
95 W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */
96 W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */
97 W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */
98 /* ----------------------------------------------- */
99 /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
100};
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100101#undef W
102
Masami Hiramatsuf438d912007-10-16 01:27:49 -0700103struct kretprobe_blackpoint kretprobe_blacklist[] = {
104 {"__switch_to", }, /* This function switches only current task, but
105 doesn't switch kernel stack.*/
106 {NULL, NULL} /* Terminator */
107};
108const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
109
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500110static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100111{
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500112 struct __arch_relative_insn {
113 u8 op;
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100114 s32 raddr;
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500115 } __attribute__((packed)) *insn;
116
117 insn = (struct __arch_relative_insn *)from;
118 insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
119 insn->op = op;
120}
121
122/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
123static void __kprobes synthesize_reljump(void *from, void *to)
124{
125 __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE);
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100126}
127
128/*
Harvey Harrison99309272008-01-30 13:32:14 +0100129 * Check for the REX prefix which can only exist on X86_64
130 * X86_32 always returns 0
131 */
132static int __kprobes is_REX_prefix(kprobe_opcode_t *insn)
133{
134#ifdef CONFIG_X86_64
135 if ((*insn & 0xf0) == 0x40)
136 return 1;
137#endif
138 return 0;
139}
140
141/*
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100142 * Returns non-zero if opcode is boostable.
143 * RIP relative instructions are adjusted at copying time in 64 bits mode
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100144 */
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100145static int __kprobes can_boost(kprobe_opcode_t *opcodes)
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100146{
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100147 kprobe_opcode_t opcode;
148 kprobe_opcode_t *orig_opcodes = opcodes;
149
Jaswinder Singh Rajputcde5edb2009-03-18 17:37:45 +0530150 if (search_exception_tables((unsigned long)opcodes))
Masami Hiramatsu30390882009-03-16 18:57:22 -0400151 return 0; /* Page fault may occur on this address. */
152
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100153retry:
154 if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
155 return 0;
156 opcode = *(opcodes++);
157
158 /* 2nd-byte opcode */
159 if (opcode == 0x0f) {
160 if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
161 return 0;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100162 return test_bit(*opcodes,
163 (unsigned long *)twobyte_is_boostable);
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100164 }
165
166 switch (opcode & 0xf0) {
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100167#ifdef CONFIG_X86_64
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100168 case 0x40:
169 goto retry; /* REX prefix is boostable */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100170#endif
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100171 case 0x60:
172 if (0x63 < opcode && opcode < 0x67)
173 goto retry; /* prefixes */
174 /* can't boost Address-size override and bound */
175 return (opcode != 0x62 && opcode != 0x67);
176 case 0x70:
177 return 0; /* can't boost conditional jump */
178 case 0xc0:
179 /* can't boost software-interruptions */
180 return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
181 case 0xd0:
182 /* can boost AA* and XLAT */
183 return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
184 case 0xe0:
185 /* can boost in/out and absolute jmps */
186 return ((opcode & 0x04) || opcode == 0xea);
187 case 0xf0:
188 if ((opcode & 0x0c) == 0 && opcode != 0xf1)
189 goto retry; /* lock/rep(ne) prefix */
190 /* clear and set flags are boostable */
191 return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
192 default:
193 /* segment override prefixes are boostable */
194 if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
195 goto retry; /* prefixes */
196 /* CS override prefix and call are not boostable */
197 return (opcode != 0x2e && opcode != 0x9a);
198 }
199}
200
Masami Hiramatsub46b3d72009-08-13 16:34:28 -0400201/* Recover the probed instruction at addr for further analysis. */
202static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
203{
204 struct kprobe *kp;
205 kp = get_kprobe((void *)addr);
206 if (!kp)
207 return -EINVAL;
208
209 /*
210 * Basically, kp->ainsn.insn has an original instruction.
211 * However, RIP-relative instruction can not do single-stepping
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500212 * at different place, __copy_instruction() tweaks the displacement of
Masami Hiramatsub46b3d72009-08-13 16:34:28 -0400213 * that instruction. In that case, we can't recover the instruction
214 * from the kp->ainsn.insn.
215 *
216 * On the other hand, kp->opcode has a copy of the first byte of
217 * the probed instruction, which is overwritten by int3. And
218 * the instruction at kp->addr is not modified by kprobes except
219 * for the first byte, we can recover the original instruction
220 * from it and kp->opcode.
221 */
222 memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
223 buf[0] = kp->opcode;
224 return 0;
225}
226
227/* Dummy buffers for kallsyms_lookup */
228static char __dummy_buf[KSYM_NAME_LEN];
229
230/* Check if paddr is at an instruction boundary */
231static int __kprobes can_probe(unsigned long paddr)
232{
233 int ret;
234 unsigned long addr, offset = 0;
235 struct insn insn;
236 kprobe_opcode_t buf[MAX_INSN_SIZE];
237
238 if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf))
239 return 0;
240
241 /* Decode instructions */
242 addr = paddr - offset;
243 while (addr < paddr) {
244 kernel_insn_init(&insn, (void *)addr);
245 insn_get_opcode(&insn);
246
247 /*
248 * Check if the instruction has been modified by another
249 * kprobe, in which case we replace the breakpoint by the
250 * original instruction in our buffer.
251 */
252 if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
253 ret = recover_probed_instruction(buf, addr);
254 if (ret)
255 /*
256 * Another debugging subsystem might insert
257 * this breakpoint. In that case, we can't
258 * recover it.
259 */
260 return 0;
261 kernel_insn_init(&insn, buf);
262 }
263 insn_get_length(&insn);
264 addr += insn.length;
265 }
266
267 return (addr == paddr);
268}
269
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270/*
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100271 * Returns non-zero if opcode modifies the interrupt flag.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 */
Andrew Morton86454192007-11-26 20:42:19 +0100273static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274{
275 switch (*insn) {
276 case 0xfa: /* cli */
277 case 0xfb: /* sti */
278 case 0xcf: /* iret/iretd */
279 case 0x9d: /* popf/popfd */
280 return 1;
281 }
Harvey Harrison99309272008-01-30 13:32:14 +0100282
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100283 /*
Harvey Harrison99309272008-01-30 13:32:14 +0100284 * on X86_64, 0x40-0x4f are REX prefixes so we need to look
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100285 * at the next byte instead.. but of course not recurse infinitely
286 */
Harvey Harrison99309272008-01-30 13:32:14 +0100287 if (is_REX_prefix(insn))
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100288 return is_IF_modifier(++insn);
Harvey Harrison99309272008-01-30 13:32:14 +0100289
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 return 0;
291}
292
293/*
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500294 * Copy an instruction and adjust the displacement if the instruction
295 * uses the %rip-relative addressing mode.
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100296 * If it does, Return the address of the 32-bit displacement word.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 * If not, return null.
Harvey Harrison31f80e42008-01-30 13:32:16 +0100298 * Only applicable to 64-bit x86.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 */
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500300static int __kprobes __copy_instruction(u8 *dest, u8 *src, int recover)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301{
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400302 struct insn insn;
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500303 int ret;
304 kprobe_opcode_t buf[MAX_INSN_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500306 kernel_insn_init(&insn, src);
307 if (recover) {
308 insn_get_opcode(&insn);
309 if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
310 ret = recover_probed_instruction(buf,
311 (unsigned long)src);
312 if (ret)
313 return 0;
314 kernel_insn_init(&insn, buf);
315 }
316 }
317 insn_get_length(&insn);
318 memcpy(dest, insn.kaddr, insn.length);
319
320#ifdef CONFIG_X86_64
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400321 if (insn_rip_relative(&insn)) {
322 s64 newdisp;
323 u8 *disp;
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500324 kernel_insn_init(&insn, dest);
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400325 insn_get_displacement(&insn);
326 /*
327 * The copied instruction uses the %rip-relative addressing
328 * mode. Adjust the displacement for the difference between
329 * the original location of this instruction and the location
330 * of the copy that will actually be run. The tricky bit here
331 * is making sure that the sign extension happens correctly in
332 * this calculation, since we need a signed 32-bit result to
333 * be sign-extended to 64 bits when it's added to the %rip
334 * value and yield the same 64-bit result that the sign-
335 * extension of the original signed 32-bit displacement would
336 * have given.
337 */
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500338 newdisp = (u8 *) src + (s64) insn.displacement.value -
339 (u8 *) dest;
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400340 BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500341 disp = (u8 *) dest + insn_offset_displacement(&insn);
Masami Hiramatsu89ae4652009-08-13 16:34:36 -0400342 *(s32 *) disp = (s32) newdisp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 }
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100344#endif
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500345 return insn.length;
Harvey Harrison31f80e42008-01-30 13:32:16 +0100346}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
Keshavamurthy Anil Sf709b122006-01-09 20:52:44 -0800348static void __kprobes arch_copy_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349{
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500350 /*
351 * Copy an instruction without recovering int3, because it will be
352 * put by another subsystem.
353 */
354 __copy_instruction(p->ainsn.insn, p->addr, 0);
Harvey Harrison31f80e42008-01-30 13:32:16 +0100355
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100356 if (can_boost(p->addr))
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100357 p->ainsn.boostable = 0;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100358 else
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100359 p->ainsn.boostable = -1;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100360
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700361 p->opcode = *p->addr;
362}
363
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100364int __kprobes arch_prepare_kprobe(struct kprobe *p)
365{
Masami Hiramatsu4554dbc2010-02-02 16:49:18 -0500366 if (alternatives_text_reserved(p->addr, p->addr))
367 return -EINVAL;
368
Masami Hiramatsub46b3d72009-08-13 16:34:28 -0400369 if (!can_probe((unsigned long)p->addr))
370 return -EILSEQ;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100371 /* insn: must be on special executable page on x86. */
372 p->ainsn.insn = get_insn_slot();
373 if (!p->ainsn.insn)
374 return -ENOMEM;
375 arch_copy_kprobe(p);
376 return 0;
377}
378
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700379void __kprobes arch_arm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700380{
Andi Kleen19d36cc2007-07-22 11:12:31 +0200381 text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700382}
383
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700384void __kprobes arch_disarm_kprobe(struct kprobe *p)
Rusty Lynch7e1048b2005-06-23 00:09:25 -0700385{
Andi Kleen19d36cc2007-07-22 11:12:31 +0200386 text_poke(p->addr, &p->opcode, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387}
388
Ananth N Mavinakayanahalli0498b632006-01-09 20:52:46 -0800389void __kprobes arch_remove_kprobe(struct kprobe *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390{
Masami Hiramatsu12941562009-01-06 14:41:50 -0800391 if (p->ainsn.insn) {
392 free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
393 p->ainsn.insn = NULL;
394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
396
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700397static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700398{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800399 kcb->prev_kprobe.kp = kprobe_running();
400 kcb->prev_kprobe.status = kcb->kprobe_status;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100401 kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags;
402 kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700403}
404
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700405static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700406{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800407 __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
408 kcb->kprobe_status = kcb->prev_kprobe.status;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100409 kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags;
410 kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700411}
412
Prasanna S Panchamukhi3b602112006-04-18 22:22:00 -0700413static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800414 struct kprobe_ctlblk *kcb)
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700415{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800416 __get_cpu_var(current_kprobe) = p;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100417 kcb->kprobe_saved_flags = kcb->kprobe_old_flags
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100418 = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700419 if (is_IF_modifier(p->ainsn.insn))
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100420 kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700421}
422
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100423static void __kprobes clear_btf(void)
Roland McGrath1ecc7982008-01-30 13:30:54 +0100424{
425 if (test_thread_flag(TIF_DEBUGCTLMSR))
Jan Beulich5b0e5082008-03-10 13:11:17 +0000426 update_debugctlmsr(0);
Roland McGrath1ecc7982008-01-30 13:30:54 +0100427}
428
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100429static void __kprobes restore_btf(void)
Roland McGrath1ecc7982008-01-30 13:30:54 +0100430{
431 if (test_thread_flag(TIF_DEBUGCTLMSR))
Jan Beulich5b0e5082008-03-10 13:11:17 +0000432 update_debugctlmsr(current->thread.debugctlmsr);
Roland McGrath1ecc7982008-01-30 13:30:54 +0100433}
434
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700435void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700436 struct pt_regs *regs)
Rusty Lynch73649da2005-06-23 00:09:23 -0700437{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100438 unsigned long *sara = stack_addr(regs);
Rusty Lynch73649da2005-06-23 00:09:23 -0700439
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700440 ri->ret_addr = (kprobe_opcode_t *) *sara;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100441
Christoph Hellwig4c4308c2007-05-08 00:34:14 -0700442 /* Replace the return addr with trampoline addr */
443 *sara = (unsigned long) &kretprobe_trampoline;
Rusty Lynch73649da2005-06-23 00:09:23 -0700444}
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100445
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500446#ifdef CONFIG_OPTPROBES
447static int __kprobes setup_detour_execution(struct kprobe *p,
448 struct pt_regs *regs,
449 int reenter);
450#else
451#define setup_detour_execution(p, regs, reenter) (0)
452#endif
453
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100454static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500455 struct kprobe_ctlblk *kcb, int reenter)
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100456{
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500457 if (setup_detour_execution(p, regs, reenter))
458 return;
459
Masami Hiramatsu615d0eb2010-02-02 16:49:04 -0500460#if !defined(CONFIG_PREEMPT)
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100461 if (p->ainsn.boostable == 1 && !p->post_handler) {
462 /* Boost up -- we can execute copied instructions directly */
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500463 if (!reenter)
464 reset_current_kprobe();
465 /*
466 * Reentering boosted probe doesn't reset current_kprobe,
467 * nor set current_kprobe, because it doesn't use single
468 * stepping.
469 */
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100470 regs->ip = (unsigned long)p->ainsn.insn;
471 preempt_enable_no_resched();
472 return;
473 }
474#endif
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500475 if (reenter) {
476 save_previous_kprobe(kcb);
477 set_current_kprobe(p, regs, kcb);
478 kcb->kprobe_status = KPROBE_REENTER;
479 } else
480 kcb->kprobe_status = KPROBE_HIT_SS;
481 /* Prepare real single stepping */
482 clear_btf();
483 regs->flags |= X86_EFLAGS_TF;
484 regs->flags &= ~X86_EFLAGS_IF;
485 /* single step inline if the instruction is an int3 */
486 if (p->opcode == BREAKPOINT_INSTRUCTION)
487 regs->ip = (unsigned long)p->addr;
488 else
489 regs->ip = (unsigned long)p->ainsn.insn;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100490}
491
Harvey Harrison40102d42008-01-30 13:32:02 +0100492/*
493 * We have reentered the kprobe_handler(), since another probe was hit while
494 * within the handler. We save the original kprobes variables and just single
495 * step on the instruction of the new probe without calling any user handlers.
496 */
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100497static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs,
498 struct kprobe_ctlblk *kcb)
Harvey Harrison40102d42008-01-30 13:32:02 +0100499{
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100500 switch (kcb->kprobe_status) {
501 case KPROBE_HIT_SSDONE:
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100502 case KPROBE_HIT_ACTIVE:
Abhishek Sagarfb8830e2008-01-30 13:33:13 +0100503 kprobes_inc_nmissed_count(p);
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500504 setup_singlestep(p, regs, kcb, 1);
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100505 break;
506 case KPROBE_HIT_SS:
Masami Hiramatsue9afe9e2009-08-27 13:22:58 -0400507 /* A probe has been hit in the codepath leading up to, or just
508 * after, single-stepping of a probed instruction. This entire
509 * codepath should strictly reside in .kprobes.text section.
510 * Raise a BUG or we'll continue in an endless reentering loop
511 * and eventually a stack overflow.
512 */
513 printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n",
514 p->addr);
515 dump_kprobe(p);
516 BUG();
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100517 default:
518 /* impossible cases */
519 WARN_ON(1);
Abhishek Sagarfb8830e2008-01-30 13:33:13 +0100520 return 0;
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100521 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100522
Masami Hiramatsu59e87cd2008-01-30 13:32:02 +0100523 return 1;
Harvey Harrison40102d42008-01-30 13:32:02 +0100524}
Rusty Lynch73649da2005-06-23 00:09:23 -0700525
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100526/*
527 * Interrupts are disabled on entry as trap3 is an interrupt gate and they
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200528 * remain disabled throughout this function.
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100529 */
530static int __kprobes kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100532 kprobe_opcode_t *addr;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100533 struct kprobe *p;
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800534 struct kprobe_ctlblk *kcb;
535
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100536 addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100537 if (*addr != BREAKPOINT_INSTRUCTION) {
538 /*
539 * The breakpoint instruction was removed right
540 * after we hit it. Another cpu has removed
541 * either a probepoint or a debugger breakpoint
542 * at this address. In either case, no further
543 * handling of this interrupt is appropriate.
544 * Back up over the (now missing) int3 and run
545 * the original instruction.
546 */
547 regs->ip = (unsigned long)addr;
548 return 1;
549 }
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100550
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800551 /*
552 * We don't want to be preempted for the entire
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100553 * duration of kprobe processing. We conditionally
554 * re-enable preemption at the end of this function,
555 * and also in reenter_kprobe() and setup_singlestep().
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800556 */
557 preempt_disable();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100559 kcb = get_kprobe_ctlblk();
Harvey Harrisonb9760152008-01-30 13:32:19 +0100560 p = get_kprobe(addr);
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100561
Harvey Harrisonb9760152008-01-30 13:32:19 +0100562 if (p) {
Harvey Harrisonb9760152008-01-30 13:32:19 +0100563 if (kprobe_running()) {
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100564 if (reenter_kprobe(p, regs, kcb))
565 return 1;
Harvey Harrisonb9760152008-01-30 13:32:19 +0100566 } else {
567 set_current_kprobe(p, regs, kcb);
568 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100569
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 /*
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100571 * If we have no pre-handler or it returned 0, we
572 * continue with normal processing. If we have a
573 * pre-handler and it returned non-zero, it prepped
574 * for calling the break_handler below on re-entry
575 * for jprobe processing, so get out doing nothing
576 * more here.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 */
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100578 if (!p->pre_handler || !p->pre_handler(p, regs))
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500579 setup_singlestep(p, regs, kcb, 0);
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100580 return 1;
Harvey Harrisonb9760152008-01-30 13:32:19 +0100581 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100582 } else if (kprobe_running()) {
583 p = __get_cpu_var(current_kprobe);
584 if (p->break_handler && p->break_handler(p, regs)) {
Masami Hiramatsu0f94eb62010-02-25 08:34:23 -0500585 setup_singlestep(p, regs, kcb, 0);
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100586 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 }
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100588 } /* else: not a kprobe fault; let the kernel handle it */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -0800590 preempt_enable_no_resched();
Abhishek Sagarf315dec2008-01-30 13:32:50 +0100591 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592}
593
Masami Hiramatsuf007ea22010-02-25 08:34:30 -0500594#ifdef CONFIG_X86_64
595#define SAVE_REGS_STRING \
596 /* Skip cs, ip, orig_ax. */ \
597 " subq $24, %rsp\n" \
598 " pushq %rdi\n" \
599 " pushq %rsi\n" \
600 " pushq %rdx\n" \
601 " pushq %rcx\n" \
602 " pushq %rax\n" \
603 " pushq %r8\n" \
604 " pushq %r9\n" \
605 " pushq %r10\n" \
606 " pushq %r11\n" \
607 " pushq %rbx\n" \
608 " pushq %rbp\n" \
609 " pushq %r12\n" \
610 " pushq %r13\n" \
611 " pushq %r14\n" \
612 " pushq %r15\n"
613#define RESTORE_REGS_STRING \
614 " popq %r15\n" \
615 " popq %r14\n" \
616 " popq %r13\n" \
617 " popq %r12\n" \
618 " popq %rbp\n" \
619 " popq %rbx\n" \
620 " popq %r11\n" \
621 " popq %r10\n" \
622 " popq %r9\n" \
623 " popq %r8\n" \
624 " popq %rax\n" \
625 " popq %rcx\n" \
626 " popq %rdx\n" \
627 " popq %rsi\n" \
628 " popq %rdi\n" \
629 /* Skip orig_ax, ip, cs */ \
630 " addq $24, %rsp\n"
631#else
632#define SAVE_REGS_STRING \
633 /* Skip cs, ip, orig_ax and gs. */ \
634 " subl $16, %esp\n" \
635 " pushl %fs\n" \
636 " pushl %ds\n" \
637 " pushl %es\n" \
638 " pushl %eax\n" \
639 " pushl %ebp\n" \
640 " pushl %edi\n" \
641 " pushl %esi\n" \
642 " pushl %edx\n" \
643 " pushl %ecx\n" \
644 " pushl %ebx\n"
645#define RESTORE_REGS_STRING \
646 " popl %ebx\n" \
647 " popl %ecx\n" \
648 " popl %edx\n" \
649 " popl %esi\n" \
650 " popl %edi\n" \
651 " popl %ebp\n" \
652 " popl %eax\n" \
653 /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\
654 " addl $24, %esp\n"
655#endif
656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657/*
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100658 * When a retprobed function returns, this code saves registers and
659 * calls trampoline_handler() runs, which calls the kretprobe's handler.
Rusty Lynch73649da2005-06-23 00:09:23 -0700660 */
Harvey Harrisonf1452d42008-02-14 15:23:53 -0800661static void __used __kprobes kretprobe_trampoline_holder(void)
Harvey Harrison10175792008-01-30 13:33:01 +0100662{
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100663 asm volatile (
664 ".global kretprobe_trampoline\n"
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100665 "kretprobe_trampoline: \n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100666#ifdef CONFIG_X86_64
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100667 /* We don't bother saving the ss register */
668 " pushq %rsp\n"
669 " pushfq\n"
Masami Hiramatsuf007ea22010-02-25 08:34:30 -0500670 SAVE_REGS_STRING
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100671 " movq %rsp, %rdi\n"
672 " call trampoline_handler\n"
673 /* Replace saved sp with true return address. */
674 " movq %rax, 152(%rsp)\n"
Masami Hiramatsuf007ea22010-02-25 08:34:30 -0500675 RESTORE_REGS_STRING
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100676 " popfq\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100677#else
678 " pushf\n"
Masami Hiramatsuf007ea22010-02-25 08:34:30 -0500679 SAVE_REGS_STRING
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100680 " movl %esp, %eax\n"
681 " call trampoline_handler\n"
682 /* Move flags to cs */
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400683 " movl 56(%esp), %edx\n"
684 " movl %edx, 52(%esp)\n"
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100685 /* Replace saved flags with true return address. */
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400686 " movl %eax, 56(%esp)\n"
Masami Hiramatsuf007ea22010-02-25 08:34:30 -0500687 RESTORE_REGS_STRING
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100688 " popf\n"
689#endif
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100690 " ret\n");
Harvey Harrison10175792008-01-30 13:33:01 +0100691}
Rusty Lynch73649da2005-06-23 00:09:23 -0700692
693/*
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100694 * Called from kretprobe_trampoline
Rusty Lynch73649da2005-06-23 00:09:23 -0700695 */
Harvey Harrisonf1452d42008-02-14 15:23:53 -0800696static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
Rusty Lynch73649da2005-06-23 00:09:23 -0700697{
bibo,mao62c27be2006-10-02 02:17:33 -0700698 struct kretprobe_instance *ri = NULL;
bibo,mao99219a32006-10-02 02:17:35 -0700699 struct hlist_head *head, empty_rp;
bibo,mao62c27be2006-10-02 02:17:33 -0700700 struct hlist_node *node, *tmp;
Ananth N Mavinakayanahalli991a51d2005-11-07 01:00:14 -0800701 unsigned long flags, orig_ret_address = 0;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100702 unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
Rusty Lynch73649da2005-06-23 00:09:23 -0700703
bibo,mao99219a32006-10-02 02:17:35 -0700704 INIT_HLIST_HEAD(&empty_rp);
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700705 kretprobe_hash_lock(current, &head, &flags);
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100706 /* fixup registers */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100707#ifdef CONFIG_X86_64
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100708 regs->cs = __KERNEL_CS;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100709#else
710 regs->cs = __KERNEL_CS | get_kernel_rpl();
Masami Hiramatsufee039a2009-03-23 10:14:52 -0400711 regs->gs = 0;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100712#endif
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100713 regs->ip = trampoline_address;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100714 regs->orig_ax = ~0UL;
Rusty Lynch73649da2005-06-23 00:09:23 -0700715
Rusty Lynchba8af122005-06-27 15:17:10 -0700716 /*
717 * It is possible to have multiple instances associated with a given
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100718 * task either because multiple functions in the call path have
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200719 * return probes installed on them, and/or more than one
Rusty Lynchba8af122005-06-27 15:17:10 -0700720 * return probe was registered for a target function.
721 *
722 * We can handle this because:
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100723 * - instances are always pushed into the head of the list
Rusty Lynchba8af122005-06-27 15:17:10 -0700724 * - when multiple return probes are registered for the same
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100725 * function, the (chronologically) first instance's ret_addr
726 * will be the real return address, and all the rest will
727 * point to kretprobe_trampoline.
Rusty Lynchba8af122005-06-27 15:17:10 -0700728 */
729 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
bibo,mao62c27be2006-10-02 02:17:33 -0700730 if (ri->task != current)
Rusty Lynchba8af122005-06-27 15:17:10 -0700731 /* another task is sharing our hash bucket */
bibo,mao62c27be2006-10-02 02:17:33 -0700732 continue;
Rusty Lynch73649da2005-06-23 00:09:23 -0700733
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100734 if (ri->rp && ri->rp->handler) {
735 __get_cpu_var(current_kprobe) = &ri->rp->kp;
736 get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
Rusty Lynchba8af122005-06-27 15:17:10 -0700737 ri->rp->handler(ri, regs);
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100738 __get_cpu_var(current_kprobe) = NULL;
739 }
Rusty Lynch73649da2005-06-23 00:09:23 -0700740
Rusty Lynchba8af122005-06-27 15:17:10 -0700741 orig_ret_address = (unsigned long)ri->ret_addr;
bibo,mao99219a32006-10-02 02:17:35 -0700742 recycle_rp_inst(ri, &empty_rp);
Rusty Lynchba8af122005-06-27 15:17:10 -0700743
744 if (orig_ret_address != trampoline_address)
745 /*
746 * This is the real return address. Any other
747 * instances associated with this task are for
748 * other calls deeper on the call stack
749 */
750 break;
Rusty Lynch73649da2005-06-23 00:09:23 -0700751 }
Rusty Lynchba8af122005-06-27 15:17:10 -0700752
Ananth N Mavinakayanahalli0f95b7f2007-05-08 00:28:27 -0700753 kretprobe_assert(ri, orig_ret_address, trampoline_address);
Rusty Lynchba8af122005-06-27 15:17:10 -0700754
Srinivasa D Sef53d9c2008-07-25 01:46:04 -0700755 kretprobe_hash_unlock(current, &flags);
Rusty Lynchba8af122005-06-27 15:17:10 -0700756
bibo,mao99219a32006-10-02 02:17:35 -0700757 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
758 hlist_del(&ri->hlist);
759 kfree(ri);
760 }
Masami Hiramatsuda07ab02008-01-30 13:31:21 +0100761 return (void *)orig_ret_address;
Rusty Lynch73649da2005-06-23 00:09:23 -0700762}
763
764/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 * Called after single-stepping. p->addr is the address of the
766 * instruction whose first byte has been replaced by the "int 3"
767 * instruction. To avoid the SMP problems that can occur when we
768 * temporarily put back the original opcode to single-step, we
769 * single-stepped a copy of the instruction. The address of this
770 * copy is p->ainsn.insn.
771 *
772 * This function prepares to return from the post-single-step
773 * interrupt. We have to fix up the stack as follows:
774 *
775 * 0) Except in the case of absolute or indirect jump or call instructions,
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100776 * the new ip is relative to the copied instruction. We need to make
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 * it relative to the original instruction.
778 *
779 * 1) If the single-stepped instruction was pushfl, then the TF and IF
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100780 * flags are set in the just-pushed flags, and may need to be cleared.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 *
782 * 2) If the single-stepped instruction was a call, the return address
783 * that is atop the stack is the address following the copied instruction.
784 * We need to make it the address following the original instruction.
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100785 *
786 * If this is the first time we've single-stepped the instruction at
787 * this probepoint, and the instruction is boostable, boost it: add a
788 * jump instruction after the copied instruction, that jumps to the next
789 * instruction after the probepoint.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800791static void __kprobes resume_execution(struct kprobe *p,
792 struct pt_regs *regs, struct kprobe_ctlblk *kcb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793{
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100794 unsigned long *tos = stack_addr(regs);
795 unsigned long copy_ip = (unsigned long)p->ainsn.insn;
796 unsigned long orig_ip = (unsigned long)p->addr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700797 kprobe_opcode_t *insn = p->ainsn.insn;
798
799 /*skip the REX prefix*/
Harvey Harrison99309272008-01-30 13:32:14 +0100800 if (is_REX_prefix(insn))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 insn++;
802
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100803 regs->flags &= ~X86_EFLAGS_TF;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804 switch (*insn) {
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100805 case 0x9c: /* pushfl */
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100806 *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100807 *tos |= kcb->kprobe_old_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 break;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100809 case 0xc2: /* iret/ret/lret */
810 case 0xc3:
Prasanna S Panchamukhi0b9e2ca2005-05-05 16:15:40 -0700811 case 0xca:
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100812 case 0xcb:
813 case 0xcf:
814 case 0xea: /* jmp absolute -- ip is correct */
815 /* ip is already adjusted, no more changes required */
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100816 p->ainsn.boostable = 1;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100817 goto no_change;
818 case 0xe8: /* call relative - Fix return addr */
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100819 *tos = orig_ip + (*tos - copy_ip);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 break;
Harvey Harrisone7b5e112008-01-30 13:31:43 +0100821#ifdef CONFIG_X86_32
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100822 case 0x9a: /* call absolute -- same as call absolute, indirect */
823 *tos = orig_ip + (*tos - copy_ip);
824 goto no_change;
825#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 case 0xff:
Satoshi Oshimadc49e342006-05-20 15:00:21 -0700827 if ((insn[1] & 0x30) == 0x10) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100828 /*
829 * call absolute, indirect
830 * Fix return addr; ip is correct.
831 * But this is not boostable
832 */
833 *tos = orig_ip + (*tos - copy_ip);
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100834 goto no_change;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100835 } else if (((insn[1] & 0x31) == 0x20) ||
836 ((insn[1] & 0x31) == 0x21)) {
837 /*
838 * jmp near and far, absolute indirect
839 * ip is correct. And this is boostable
840 */
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100841 p->ainsn.boostable = 1;
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100842 goto no_change;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 default:
845 break;
846 }
847
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100848 if (p->ainsn.boostable == 0) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100849 if ((regs->ip > copy_ip) &&
850 (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100851 /*
852 * These instructions can be executed directly if it
853 * jumps back to correct address.
854 */
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -0500855 synthesize_reljump((void *)regs->ip,
856 (void *)orig_ip + (regs->ip - copy_ip));
Masami Hiramatsuaa470142008-01-30 13:31:21 +0100857 p->ainsn.boostable = 1;
858 } else {
859 p->ainsn.boostable = -1;
860 }
861 }
862
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100863 regs->ip += orig_ip - copy_ip;
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100864
Masami Hiramatsu0b0122f2007-12-18 18:05:58 +0100865no_change:
Roland McGrath1ecc7982008-01-30 13:30:54 +0100866 restore_btf();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867}
868
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100869/*
870 * Interrupts are disabled on entry as trap1 is an interrupt gate and they
André Goddard Rosaaf901ca2009-11-14 13:09:05 -0200871 * remain disabled throughout this function.
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100872 */
873static int __kprobes post_kprobe_handler(struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800875 struct kprobe *cur = kprobe_running();
876 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
877
878 if (!cur)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 return 0;
880
Yakov Lerneracb5b8a2008-03-16 03:21:21 -0500881 resume_execution(cur, regs, kcb);
882 regs->flags |= kcb->kprobe_saved_flags;
Yakov Lerneracb5b8a2008-03-16 03:21:21 -0500883
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800884 if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
885 kcb->kprobe_status = KPROBE_HIT_SSDONE;
886 cur->post_handler(cur, regs, 0);
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700887 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700888
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100889 /* Restore back the original saved kprobes variables and continue. */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800890 if (kcb->kprobe_status == KPROBE_REENTER) {
891 restore_previous_kprobe(kcb);
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700892 goto out;
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700893 }
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800894 reset_current_kprobe();
Prasanna S Panchamukhiaa3d7e32005-06-23 00:09:37 -0700895out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 preempt_enable_no_resched();
897
898 /*
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100899 * if somebody else is singlestepping across a probe point, flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 * will have TF set, in which case, continue the remaining processing
901 * of do_debug, as if this is not a probe hit.
902 */
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +0100903 if (regs->flags & X86_EFLAGS_TF)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700904 return 0;
905
906 return 1;
907}
908
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700909int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -0800911 struct kprobe *cur = kprobe_running();
912 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
913
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100914 switch (kcb->kprobe_status) {
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800915 case KPROBE_HIT_SS:
916 case KPROBE_REENTER:
917 /*
918 * We are here because the instruction being single
919 * stepped caused a page fault. We reset the current
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100920 * kprobe and the ip points back to the probe address
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800921 * and allow the page fault handler to continue as a
922 * normal page fault.
923 */
H. Peter Anvin65ea5b02008-01-30 13:30:56 +0100924 regs->ip = (unsigned long)cur->addr;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100925 regs->flags |= kcb->kprobe_old_flags;
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800926 if (kcb->kprobe_status == KPROBE_REENTER)
927 restore_previous_kprobe(kcb);
928 else
929 reset_current_kprobe();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 preempt_enable_no_resched();
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800931 break;
932 case KPROBE_HIT_ACTIVE:
933 case KPROBE_HIT_SSDONE:
934 /*
935 * We increment the nmissed count for accounting,
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100936 * we can also use npre/npostfault count for accounting
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800937 * these specific fault cases.
938 */
939 kprobes_inc_nmissed_count(cur);
940
941 /*
942 * We come here because instructions in the pre/post
943 * handler caused the page_fault, this could happen
944 * if handler tries to access user space by
945 * copy_from_user(), get_user() etc. Let the
946 * user-specified handler try to fix it first.
947 */
948 if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
949 return 1;
950
951 /*
952 * In case the user-specified fault handler returned
953 * zero, try to fix up.
954 */
Masami Hiramatsud6be29b2008-01-30 13:31:21 +0100955 if (fixup_exception(regs))
956 return 1;
Harvey Harrison6d485832008-01-30 13:31:41 +0100957
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800958 /*
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100959 * fixup routine could not handle it,
Prasanna S Panchamukhic28f8962006-03-26 01:38:23 -0800960 * Let do_page_fault() fix it.
961 */
962 break;
963 default:
964 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965 }
966 return 0;
967}
968
969/*
970 * Wrapper routine for handling exceptions.
971 */
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -0700972int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
973 unsigned long val, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974{
Jan Engelhardtade1af72008-01-30 13:33:23 +0100975 struct die_args *args = data;
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -0800976 int ret = NOTIFY_DONE;
977
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +0100978 if (args->regs && user_mode_vm(args->regs))
bibo,mao2326c772006-03-26 01:38:21 -0800979 return ret;
980
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 switch (val) {
982 case DIE_INT3:
983 if (kprobe_handler(args->regs))
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -0800984 ret = NOTIFY_STOP;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985 break;
986 case DIE_DEBUG:
K.Prasad62edab92009-06-01 23:47:06 +0530987 if (post_kprobe_handler(args->regs)) {
988 /*
989 * Reset the BS bit in dr6 (pointed by args->err) to
990 * denote completion of processing
991 */
992 (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -0800993 ret = NOTIFY_STOP;
K.Prasad62edab92009-06-01 23:47:06 +0530994 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 break;
996 case DIE_GPF:
Quentin Barnesb506a9d2008-01-30 13:32:32 +0100997 /*
998 * To be potentially processing a kprobe fault and to
999 * trust the result from kprobe_running(), we have
1000 * be non-preemptible.
1001 */
1002 if (!preemptible() && kprobe_running() &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 kprobe_fault_handler(args->regs, args->trapnr))
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -08001004 ret = NOTIFY_STOP;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005 break;
1006 default:
1007 break;
1008 }
Ananth N Mavinakayanahalli66ff2d02005-11-07 01:00:07 -08001009 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010}
1011
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -07001012int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013{
1014 struct jprobe *jp = container_of(p, struct jprobe, kp);
1015 unsigned long addr;
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001016 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001018 kcb->jprobe_saved_regs = *regs;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001019 kcb->jprobe_saved_sp = stack_addr(regs);
1020 addr = (unsigned long)(kcb->jprobe_saved_sp);
1021
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022 /*
1023 * As Linus pointed out, gcc assumes that the callee
1024 * owns the argument space and could overwrite it, e.g.
1025 * tailcall optimization. So, to be absolutely safe
1026 * we also save and restore enough stack bytes to cover
1027 * the argument area.
1028 */
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001029 memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001030 MIN_STACK_SIZE(addr));
Glauber de Oliveira Costa053de042008-01-30 13:31:27 +01001031 regs->flags &= ~X86_EFLAGS_IF;
Peter Zijlstra58dfe882007-10-11 22:25:25 +02001032 trace_hardirqs_off();
H. Peter Anvin65ea5b02008-01-30 13:30:56 +01001033 regs->ip = (unsigned long)(jp->entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001034 return 1;
1035}
1036
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -07001037void __kprobes jprobe_return(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001039 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
1040
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001041 asm volatile (
1042#ifdef CONFIG_X86_64
1043 " xchg %%rbx,%%rsp \n"
1044#else
1045 " xchgl %%ebx,%%esp \n"
1046#endif
1047 " int3 \n"
1048 " .globl jprobe_return_end\n"
1049 " jprobe_return_end: \n"
1050 " nop \n"::"b"
1051 (kcb->jprobe_saved_sp):"memory");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052}
1053
Prasanna S Panchamukhi0f2fbdc2005-09-06 15:19:28 -07001054int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001055{
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001056 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
H. Peter Anvin65ea5b02008-01-30 13:30:56 +01001057 u8 *addr = (u8 *) (regs->ip - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001058 struct jprobe *jp = container_of(p, struct jprobe, kp);
1059
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001060 if ((addr > (u8 *) jprobe_return) &&
1061 (addr < (u8 *) jprobe_return_end)) {
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001062 if (stack_addr(regs) != kcb->jprobe_saved_sp) {
Masami Hiramatsu29b6cd72007-12-18 18:05:58 +01001063 struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001064 printk(KERN_ERR
1065 "current sp %p does not match saved sp %p\n",
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001066 stack_addr(regs), kcb->jprobe_saved_sp);
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001067 printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 show_registers(saved_regs);
Masami Hiramatsud6be29b2008-01-30 13:31:21 +01001069 printk(KERN_ERR "Current registers\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070 show_registers(regs);
1071 BUG();
1072 }
Ananth N Mavinakayanahallie7a510f2005-11-07 01:00:12 -08001073 *regs = kcb->jprobe_saved_regs;
Masami Hiramatsu8533bbe2008-01-30 13:31:21 +01001074 memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
1075 kcb->jprobes_stack,
1076 MIN_STACK_SIZE(kcb->jprobe_saved_sp));
Ananth N Mavinakayanahallid217d542005-11-07 01:00:14 -08001077 preempt_enable_no_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 return 1;
1079 }
1080 return 0;
1081}
Rusty Lynchba8af122005-06-27 15:17:10 -07001082
Masami Hiramatsuc0f7ac32010-02-25 08:34:46 -05001083
1084#ifdef CONFIG_OPTPROBES
1085
1086/* Insert a call instruction at address 'from', which calls address 'to'.*/
1087static void __kprobes synthesize_relcall(void *from, void *to)
1088{
1089 __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
1090}
1091
1092/* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */
1093static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr,
1094 unsigned long val)
1095{
1096#ifdef CONFIG_X86_64
1097 *addr++ = 0x48;
1098 *addr++ = 0xbf;
1099#else
1100 *addr++ = 0xb8;
1101#endif
1102 *(unsigned long *)addr = val;
1103}
1104
1105void __kprobes kprobes_optinsn_template_holder(void)
1106{
1107 asm volatile (
1108 ".global optprobe_template_entry\n"
1109 "optprobe_template_entry: \n"
1110#ifdef CONFIG_X86_64
1111 /* We don't bother saving the ss register */
1112 " pushq %rsp\n"
1113 " pushfq\n"
1114 SAVE_REGS_STRING
1115 " movq %rsp, %rsi\n"
1116 ".global optprobe_template_val\n"
1117 "optprobe_template_val: \n"
1118 ASM_NOP5
1119 ASM_NOP5
1120 ".global optprobe_template_call\n"
1121 "optprobe_template_call: \n"
1122 ASM_NOP5
1123 /* Move flags to rsp */
1124 " movq 144(%rsp), %rdx\n"
1125 " movq %rdx, 152(%rsp)\n"
1126 RESTORE_REGS_STRING
1127 /* Skip flags entry */
1128 " addq $8, %rsp\n"
1129 " popfq\n"
1130#else /* CONFIG_X86_32 */
1131 " pushf\n"
1132 SAVE_REGS_STRING
1133 " movl %esp, %edx\n"
1134 ".global optprobe_template_val\n"
1135 "optprobe_template_val: \n"
1136 ASM_NOP5
1137 ".global optprobe_template_call\n"
1138 "optprobe_template_call: \n"
1139 ASM_NOP5
1140 RESTORE_REGS_STRING
1141 " addl $4, %esp\n" /* skip cs */
1142 " popf\n"
1143#endif
1144 ".global optprobe_template_end\n"
1145 "optprobe_template_end: \n");
1146}
1147
1148#define TMPL_MOVE_IDX \
1149 ((long)&optprobe_template_val - (long)&optprobe_template_entry)
1150#define TMPL_CALL_IDX \
1151 ((long)&optprobe_template_call - (long)&optprobe_template_entry)
1152#define TMPL_END_IDX \
1153 ((long)&optprobe_template_end - (long)&optprobe_template_entry)
1154
1155#define INT3_SIZE sizeof(kprobe_opcode_t)
1156
1157/* Optimized kprobe call back function: called from optinsn */
1158static void __kprobes optimized_callback(struct optimized_kprobe *op,
1159 struct pt_regs *regs)
1160{
1161 struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
1162
1163 preempt_disable();
1164 if (kprobe_running()) {
1165 kprobes_inc_nmissed_count(&op->kp);
1166 } else {
1167 /* Save skipped registers */
1168#ifdef CONFIG_X86_64
1169 regs->cs = __KERNEL_CS;
1170#else
1171 regs->cs = __KERNEL_CS | get_kernel_rpl();
1172 regs->gs = 0;
1173#endif
1174 regs->ip = (unsigned long)op->kp.addr + INT3_SIZE;
1175 regs->orig_ax = ~0UL;
1176
1177 __get_cpu_var(current_kprobe) = &op->kp;
1178 kcb->kprobe_status = KPROBE_HIT_ACTIVE;
1179 opt_pre_handler(&op->kp, regs);
1180 __get_cpu_var(current_kprobe) = NULL;
1181 }
1182 preempt_enable_no_resched();
1183}
1184
1185static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
1186{
1187 int len = 0, ret;
1188
1189 while (len < RELATIVEJUMP_SIZE) {
1190 ret = __copy_instruction(dest + len, src + len, 1);
1191 if (!ret || !can_boost(dest + len))
1192 return -EINVAL;
1193 len += ret;
1194 }
1195 /* Check whether the address range is reserved */
1196 if (ftrace_text_reserved(src, src + len - 1) ||
1197 alternatives_text_reserved(src, src + len - 1))
1198 return -EBUSY;
1199
1200 return len;
1201}
1202
1203/* Check whether insn is indirect jump */
1204static int __kprobes insn_is_indirect_jump(struct insn *insn)
1205{
1206 return ((insn->opcode.bytes[0] == 0xff &&
1207 (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */
1208 insn->opcode.bytes[0] == 0xea); /* Segment based jump */
1209}
1210
1211/* Check whether insn jumps into specified address range */
1212static int insn_jump_into_range(struct insn *insn, unsigned long start, int len)
1213{
1214 unsigned long target = 0;
1215
1216 switch (insn->opcode.bytes[0]) {
1217 case 0xe0: /* loopne */
1218 case 0xe1: /* loope */
1219 case 0xe2: /* loop */
1220 case 0xe3: /* jcxz */
1221 case 0xe9: /* near relative jump */
1222 case 0xeb: /* short relative jump */
1223 break;
1224 case 0x0f:
1225 if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */
1226 break;
1227 return 0;
1228 default:
1229 if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */
1230 break;
1231 return 0;
1232 }
1233 target = (unsigned long)insn->next_byte + insn->immediate.value;
1234
1235 return (start <= target && target <= start + len);
1236}
1237
1238/* Decode whole function to ensure any instructions don't jump into target */
1239static int __kprobes can_optimize(unsigned long paddr)
1240{
1241 int ret;
1242 unsigned long addr, size = 0, offset = 0;
1243 struct insn insn;
1244 kprobe_opcode_t buf[MAX_INSN_SIZE];
1245 /* Dummy buffers for lookup_symbol_attrs */
1246 static char __dummy_buf[KSYM_NAME_LEN];
1247
1248 /* Lookup symbol including addr */
1249 if (!kallsyms_lookup(paddr, &size, &offset, NULL, __dummy_buf))
1250 return 0;
1251
1252 /* Check there is enough space for a relative jump. */
1253 if (size - offset < RELATIVEJUMP_SIZE)
1254 return 0;
1255
1256 /* Decode instructions */
1257 addr = paddr - offset;
1258 while (addr < paddr - offset + size) { /* Decode until function end */
1259 if (search_exception_tables(addr))
1260 /*
1261 * Since some fixup code will jumps into this function,
1262 * we can't optimize kprobe in this function.
1263 */
1264 return 0;
1265 kernel_insn_init(&insn, (void *)addr);
1266 insn_get_opcode(&insn);
1267 if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
1268 ret = recover_probed_instruction(buf, addr);
1269 if (ret)
1270 return 0;
1271 kernel_insn_init(&insn, buf);
1272 }
1273 insn_get_length(&insn);
1274 /* Recover address */
1275 insn.kaddr = (void *)addr;
1276 insn.next_byte = (void *)(addr + insn.length);
1277 /* Check any instructions don't jump into target */
1278 if (insn_is_indirect_jump(&insn) ||
1279 insn_jump_into_range(&insn, paddr + INT3_SIZE,
1280 RELATIVE_ADDR_SIZE))
1281 return 0;
1282 addr += insn.length;
1283 }
1284
1285 return 1;
1286}
1287
1288/* Check optimized_kprobe can actually be optimized. */
1289int __kprobes arch_check_optimized_kprobe(struct optimized_kprobe *op)
1290{
1291 int i;
1292 struct kprobe *p;
1293
1294 for (i = 1; i < op->optinsn.size; i++) {
1295 p = get_kprobe(op->kp.addr + i);
1296 if (p && !kprobe_disabled(p))
1297 return -EEXIST;
1298 }
1299
1300 return 0;
1301}
1302
1303/* Check the addr is within the optimized instructions. */
1304int __kprobes arch_within_optimized_kprobe(struct optimized_kprobe *op,
1305 unsigned long addr)
1306{
1307 return ((unsigned long)op->kp.addr <= addr &&
1308 (unsigned long)op->kp.addr + op->optinsn.size > addr);
1309}
1310
1311/* Free optimized instruction slot */
1312static __kprobes
1313void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
1314{
1315 if (op->optinsn.insn) {
1316 free_optinsn_slot(op->optinsn.insn, dirty);
1317 op->optinsn.insn = NULL;
1318 op->optinsn.size = 0;
1319 }
1320}
1321
1322void __kprobes arch_remove_optimized_kprobe(struct optimized_kprobe *op)
1323{
1324 __arch_remove_optimized_kprobe(op, 1);
1325}
1326
1327/*
1328 * Copy replacing target instructions
1329 * Target instructions MUST be relocatable (checked inside)
1330 */
1331int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
1332{
1333 u8 *buf;
1334 int ret;
1335 long rel;
1336
1337 if (!can_optimize((unsigned long)op->kp.addr))
1338 return -EILSEQ;
1339
1340 op->optinsn.insn = get_optinsn_slot();
1341 if (!op->optinsn.insn)
1342 return -ENOMEM;
1343
1344 /*
1345 * Verify if the address gap is in 2GB range, because this uses
1346 * a relative jump.
1347 */
1348 rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
1349 if (abs(rel) > 0x7fffffff)
1350 return -ERANGE;
1351
1352 buf = (u8 *)op->optinsn.insn;
1353
1354 /* Copy instructions into the out-of-line buffer */
1355 ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr);
1356 if (ret < 0) {
1357 __arch_remove_optimized_kprobe(op, 0);
1358 return ret;
1359 }
1360 op->optinsn.size = ret;
1361
1362 /* Copy arch-dep-instance from template */
1363 memcpy(buf, &optprobe_template_entry, TMPL_END_IDX);
1364
1365 /* Set probe information */
1366 synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op);
1367
1368 /* Set probe function call */
1369 synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback);
1370
1371 /* Set returning jmp instruction at the tail of out-of-line buffer */
1372 synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size,
1373 (u8 *)op->kp.addr + op->optinsn.size);
1374
1375 flush_icache_range((unsigned long) buf,
1376 (unsigned long) buf + TMPL_END_IDX +
1377 op->optinsn.size + RELATIVEJUMP_SIZE);
1378 return 0;
1379}
1380
1381/* Replace a breakpoint (int3) with a relative jump. */
1382int __kprobes arch_optimize_kprobe(struct optimized_kprobe *op)
1383{
1384 unsigned char jmp_code[RELATIVEJUMP_SIZE];
1385 s32 rel = (s32)((long)op->optinsn.insn -
1386 ((long)op->kp.addr + RELATIVEJUMP_SIZE));
1387
1388 /* Backup instructions which will be replaced by jump address */
1389 memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE,
1390 RELATIVE_ADDR_SIZE);
1391
1392 jmp_code[0] = RELATIVEJUMP_OPCODE;
1393 *(s32 *)(&jmp_code[1]) = rel;
1394
1395 /*
1396 * text_poke_smp doesn't support NMI/MCE code modifying.
1397 * However, since kprobes itself also doesn't support NMI/MCE
1398 * code probing, it's not a problem.
1399 */
1400 text_poke_smp(op->kp.addr, jmp_code, RELATIVEJUMP_SIZE);
1401 return 0;
1402}
1403
1404/* Replace a relative jump with a breakpoint (int3). */
1405void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
1406{
1407 u8 buf[RELATIVEJUMP_SIZE];
1408
1409 /* Set int3 to first byte for kprobes */
1410 buf[0] = BREAKPOINT_INSTRUCTION;
1411 memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
1412 text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE);
1413}
1414
1415static int __kprobes setup_detour_execution(struct kprobe *p,
1416 struct pt_regs *regs,
1417 int reenter)
1418{
1419 struct optimized_kprobe *op;
1420
1421 if (p->flags & KPROBE_FLAG_OPTIMIZED) {
1422 /* This kprobe is really able to run optimized path. */
1423 op = container_of(p, struct optimized_kprobe, kp);
1424 /* Detour through copied instructions */
1425 regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX;
1426 if (!reenter)
1427 reset_current_kprobe();
1428 preempt_enable_no_resched();
1429 return 1;
1430 }
1431 return 0;
1432}
1433#endif
1434
Rusty Lynch67729262005-07-05 18:54:50 -07001435int __init arch_init_kprobes(void)
Rusty Lynchba8af122005-06-27 15:17:10 -07001436{
Masami Hiramatsuda07ab02008-01-30 13:31:21 +01001437 return 0;
Rusty Lynchba8af122005-06-27 15:17:10 -07001438}
Ananth N Mavinakayanahallibf8f6e5b2007-05-08 00:34:16 -07001439
1440int __kprobes arch_trampoline_kprobe(struct kprobe *p)
1441{
Ananth N Mavinakayanahallibf8f6e5b2007-05-08 00:34:16 -07001442 return 0;
1443}