s390/uprobes: architecture backend for uprobes
Signed-off-by: Jan Willeke <willeke@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/uprobes.c b/arch/s390/kernel/uprobes.c
new file mode 100644
index 0000000..956f4f7
--- /dev/null
+++ b/arch/s390/kernel/uprobes.c
@@ -0,0 +1,332 @@
+/*
+ * User-space Probes (UProbes) for s390
+ *
+ * Copyright IBM Corp. 2014
+ * Author(s): Jan Willeke,
+ */
+
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/compat.h>
+#include <linux/kdebug.h>
+#include <asm/switch_to.h>
+#include <asm/facility.h>
+#include <asm/dis.h>
+#include "entry.h"
+
+#define UPROBE_TRAP_NR UINT_MAX
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long addr)
+{
+ return probe_is_prohibited_opcode(auprobe->insn);
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ if (psw_bits(regs->psw).eaba == PSW_AMODE_24BIT)
+ return -EINVAL;
+ if (!is_compat_task() && psw_bits(regs->psw).eaba == PSW_AMODE_31BIT)
+ return -EINVAL;
+ clear_pt_regs_flag(regs, PIF_PER_TRAP);
+ auprobe->saved_per = psw_bits(regs->psw).r;
+ auprobe->saved_int_code = regs->int_code;
+ regs->int_code = UPROBE_TRAP_NR;
+ regs->psw.addr = current->utask->xol_vaddr;
+ set_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
+ update_cr_regs(current);
+ return 0;
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *tsk)
+{
+ struct pt_regs *regs = task_pt_regs(tsk);
+
+ if (regs->int_code != UPROBE_TRAP_NR)
+ return true;
+ return false;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ int fixup = probe_get_fixup_type(auprobe->insn);
+ struct uprobe_task *utask = current->utask;
+
+ clear_tsk_thread_flag(current, TIF_UPROBE_SINGLESTEP);
+ update_cr_regs(current);
+ psw_bits(regs->psw).r = auprobe->saved_per;
+ regs->int_code = auprobe->saved_int_code;
+
+ if (fixup & FIXUP_PSW_NORMAL)
+ regs->psw.addr += utask->vaddr - utask->xol_vaddr;
+ if (fixup & FIXUP_RETURN_REGISTER) {
+ int reg = (auprobe->insn[0] & 0xf0) >> 4;
+
+ regs->gprs[reg] += utask->vaddr - utask->xol_vaddr;
+ }
+ if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
+ int ilen = insn_length(auprobe->insn[0] >> 8);
+
+ if (regs->psw.addr - utask->xol_vaddr == ilen)
+ regs->psw.addr = utask->vaddr + ilen;
+ }
+ /* If per tracing was active generate trap */
+ if (regs->psw.mask & PSW_MASK_PER)
+ do_per_trap(regs);
+ return 0;
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val,
+ void *data)
+{
+ struct die_args *args = data;
+ struct pt_regs *regs = args->regs;
+
+ if (!user_mode(regs))
+ return NOTIFY_DONE;
+ if (regs->int_code & 0x200) /* Trap during transaction */
+ return NOTIFY_DONE;
+ switch (val) {
+ case DIE_BPT:
+ if (uprobe_pre_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ break;
+ case DIE_SSTEP:
+ if (uprobe_post_sstep_notifier(regs))
+ return NOTIFY_STOP;
+ default:
+ break;
+ }
+ return NOTIFY_DONE;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ clear_thread_flag(TIF_UPROBE_SINGLESTEP);
+ regs->int_code = auprobe->saved_int_code;
+ regs->psw.addr = current->utask->vaddr;
+}
+
+unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline,
+ struct pt_regs *regs)
+{
+ unsigned long orig;
+
+ orig = regs->gprs[14];
+ regs->gprs[14] = trampoline;
+ return orig;
+}
+
+/* Instruction Emulation */
+
+static void adjust_psw_addr(psw_t *psw, unsigned long len)
+{
+ psw->addr = __rewind_psw(*psw, -len);
+}
+
+#define EMU_ILLEGAL_OP 1
+#define EMU_SPECIFICATION 2
+#define EMU_ADDRESSING 3
+
+#define emu_load_ril(ptr, output) \
+({ \
+ unsigned int mask = sizeof(*(ptr)) - 1; \
+ __typeof__(*(ptr)) input; \
+ int __rc = 0; \
+ \
+ if (!test_facility(34)) \
+ __rc = EMU_ILLEGAL_OP; \
+ else if ((u64 __force)ptr & mask) \
+ __rc = EMU_SPECIFICATION; \
+ else if (get_user(input, ptr)) \
+ __rc = EMU_ADDRESSING; \
+ else \
+ *(output) = input; \
+ __rc; \
+})
+
+#define emu_store_ril(ptr, input) \
+({ \
+ unsigned int mask = sizeof(*(ptr)) - 1; \
+ int __rc = 0; \
+ \
+ if (!test_facility(34)) \
+ __rc = EMU_ILLEGAL_OP; \
+ else if ((u64 __force)ptr & mask) \
+ __rc = EMU_SPECIFICATION; \
+ else if (put_user(*(input), ptr)) \
+ __rc = EMU_ADDRESSING; \
+ __rc; \
+})
+
+#define emu_cmp_ril(regs, ptr, cmp) \
+({ \
+ unsigned int mask = sizeof(*(ptr)) - 1; \
+ __typeof__(*(ptr)) input; \
+ int __rc = 0; \
+ \
+ if (!test_facility(34)) \
+ __rc = EMU_ILLEGAL_OP; \
+ else if ((u64 __force)ptr & mask) \
+ __rc = EMU_SPECIFICATION; \
+ else if (get_user(input, ptr)) \
+ __rc = EMU_ADDRESSING; \
+ else if (input > *(cmp)) \
+ psw_bits((regs)->psw).cc = 1; \
+ else if (input < *(cmp)) \
+ psw_bits((regs)->psw).cc = 2; \
+ else \
+ psw_bits((regs)->psw).cc = 0; \
+ __rc; \
+})
+
+struct insn_ril {
+ u8 opc0;
+ u8 reg : 4;
+ u8 opc1 : 4;
+ s32 disp;
+} __packed;
+
+union split_register {
+ u64 u64;
+ u32 u32[2];
+ u16 u16[4];
+ s64 s64;
+ s32 s32[2];
+ s16 s16[4];
+};
+
+/*
+ * pc relative instructions are emulated, since parameters may not be
+ * accessible from the xol area due to range limitations.
+ */
+static void handle_insn_ril(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ union split_register *rx;
+ struct insn_ril *insn;
+ unsigned int ilen;
+ void *uptr;
+ int rc = 0;
+
+ insn = (struct insn_ril *) &auprobe->insn;
+ rx = (union split_register *) ®s->gprs[insn->reg];
+ uptr = (void *)(regs->psw.addr + (insn->disp * 2));
+ ilen = insn_length(insn->opc0);
+
+ switch (insn->opc0) {
+ case 0xc0:
+ switch (insn->opc1) {
+ case 0x00: /* larl */
+ rx->u64 = (unsigned long)uptr;
+ break;
+ }
+ break;
+ case 0xc4:
+ switch (insn->opc1) {
+ case 0x02: /* llhrl */
+ rc = emu_load_ril((u16 __user *)uptr, &rx->u32[1]);
+ break;
+ case 0x04: /* lghrl */
+ rc = emu_load_ril((s16 __user *)uptr, &rx->u64);
+ break;
+ case 0x05: /* lhrl */
+ rc = emu_load_ril((s16 __user *)uptr, &rx->u32[1]);
+ break;
+ case 0x06: /* llghrl */
+ rc = emu_load_ril((u16 __user *)uptr, &rx->u64);
+ break;
+ case 0x08: /* lgrl */
+ rc = emu_load_ril((u64 __user *)uptr, &rx->u64);
+ break;
+ case 0x0c: /* lgfrl */
+ rc = emu_load_ril((s32 __user *)uptr, &rx->u64);
+ break;
+ case 0x0d: /* lrl */
+ rc = emu_load_ril((u32 __user *)uptr, &rx->u32[1]);
+ break;
+ case 0x0e: /* llgfrl */
+ rc = emu_load_ril((u32 __user *)uptr, &rx->u64);
+ break;
+ case 0x07: /* sthrl */
+ rc = emu_store_ril((u16 __user *)uptr, &rx->u16[3]);
+ break;
+ case 0x0b: /* stgrl */
+ rc = emu_store_ril((u64 __user *)uptr, &rx->u64);
+ break;
+ case 0x0f: /* strl */
+ rc = emu_store_ril((u32 __user *)uptr, &rx->u32[1]);
+ break;
+ }
+ break;
+ case 0xc6:
+ switch (insn->opc1) {
+ case 0x02: /* pfdrl */
+ if (!test_facility(34))
+ rc = EMU_ILLEGAL_OP;
+ break;
+ case 0x04: /* cghrl */
+ rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s64);
+ break;
+ case 0x05: /* chrl */
+ rc = emu_cmp_ril(regs, (s16 __user *)uptr, &rx->s32[1]);
+ break;
+ case 0x06: /* clghrl */
+ rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u64);
+ break;
+ case 0x07: /* clhrl */
+ rc = emu_cmp_ril(regs, (u16 __user *)uptr, &rx->u32[1]);
+ break;
+ case 0x08: /* cgrl */
+ rc = emu_cmp_ril(regs, (s64 __user *)uptr, &rx->s64);
+ break;
+ case 0x0a: /* clgrl */
+ rc = emu_cmp_ril(regs, (u64 __user *)uptr, &rx->u64);
+ break;
+ case 0x0c: /* cgfrl */
+ rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s64);
+ break;
+ case 0x0d: /* crl */
+ rc = emu_cmp_ril(regs, (s32 __user *)uptr, &rx->s32[1]);
+ break;
+ case 0x0e: /* clgfrl */
+ rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u64);
+ break;
+ case 0x0f: /* clrl */
+ rc = emu_cmp_ril(regs, (u32 __user *)uptr, &rx->u32[1]);
+ break;
+ }
+ break;
+ }
+ adjust_psw_addr(®s->psw, ilen);
+ switch (rc) {
+ case EMU_ILLEGAL_OP:
+ regs->int_code = ilen << 16 | 0x0001;
+ do_report_trap(regs, SIGILL, ILL_ILLOPC, NULL);
+ break;
+ case EMU_SPECIFICATION:
+ regs->int_code = ilen << 16 | 0x0006;
+ do_report_trap(regs, SIGILL, ILL_ILLOPC , NULL);
+ break;
+ case EMU_ADDRESSING:
+ regs->int_code = ilen << 16 | 0x0005;
+ do_report_trap(regs, SIGSEGV, SEGV_MAPERR, NULL);
+ break;
+ }
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ if ((psw_bits(regs->psw).eaba == PSW_AMODE_24BIT) ||
+ ((psw_bits(regs->psw).eaba == PSW_AMODE_31BIT) &&
+ !is_compat_task())) {
+ regs->psw.addr = __rewind_psw(regs->psw, UPROBE_SWBP_INSN_SIZE);
+ do_report_trap(regs, SIGILL, ILL_ILLADR, NULL);
+ return true;
+ }
+ if (probe_is_insn_relative_long(auprobe->insn)) {
+ handle_insn_ril(auprobe, regs);
+ return true;
+ }
+ return false;
+}