| /* |
| * arch/arm/kernel/unwind.c |
| * |
| * Copyright (C) 2008 ARM Limited |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| * |
| * |
| * Stack unwinding support for ARM |
| * |
| * An ARM EABI version of gcc is required to generate the unwind |
| * tables. For information about the structure of the unwind tables, |
| * see "Exception Handling ABI for the ARM Architecture" at: |
| * |
| * http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html |
| */ |
| |
| #ifndef __CHECKER__ |
| #if !defined (__ARM_EABI__) |
| #warning Your compiler does not have EABI support. |
| #warning ARM unwind is known to compile only with EABI compilers. |
| #warning Change compiler or disable ARM_UNWIND option. |
| #elif (__GNUC__ == 4 && __GNUC_MINOR__ <= 2) && !defined(__clang__) |
| #warning Your compiler is too buggy; it is known to not compile ARM unwind support. |
| #warning Change compiler or disable ARM_UNWIND option. |
| #endif |
| #endif /* __CHECKER__ */ |
| |
| #include <linux/kernel.h> |
| #include <linux/init.h> |
| #include <linux/export.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/spinlock.h> |
| #include <linux/list.h> |
| |
| #include <asm/stacktrace.h> |
| #include <asm/traps.h> |
| #include <asm/unwind.h> |
| |
| /* Dummy functions to avoid linker complaints */ |
| void __aeabi_unwind_cpp_pr0(void) |
| { |
| }; |
| EXPORT_SYMBOL(__aeabi_unwind_cpp_pr0); |
| |
| void __aeabi_unwind_cpp_pr1(void) |
| { |
| }; |
| EXPORT_SYMBOL(__aeabi_unwind_cpp_pr1); |
| |
| void __aeabi_unwind_cpp_pr2(void) |
| { |
| }; |
| EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2); |
| |
| struct unwind_ctrl_block { |
| unsigned long vrs[16]; /* virtual register set */ |
| const unsigned long *insn; /* pointer to the current instructions word */ |
| unsigned long sp_high; /* highest value of sp allowed */ |
| /* |
| * 1 : check for stack overflow for each register pop. |
| * 0 : save overhead if there is plenty of stack remaining. |
| */ |
| int check_each_pop; |
| int entries; /* number of entries left to interpret */ |
| int byte; /* current byte number in the instructions word */ |
| }; |
| |
| enum regs { |
| #ifdef CONFIG_THUMB2_KERNEL |
| FP = 7, |
| #else |
| FP = 11, |
| #endif |
| SP = 13, |
| LR = 14, |
| PC = 15 |
| }; |
| |
| extern const struct unwind_idx __start_unwind_idx[]; |
| static const struct unwind_idx *__origin_unwind_idx; |
| extern const struct unwind_idx __stop_unwind_idx[]; |
| |
| static DEFINE_SPINLOCK(unwind_lock); |
| static LIST_HEAD(unwind_tables); |
| |
| /* Convert a prel31 symbol to an absolute address */ |
| #define prel31_to_addr(ptr) \ |
| ({ \ |
| /* sign-extend to 32 bits */ \ |
| long offset = (((long)*(ptr)) << 1) >> 1; \ |
| (unsigned long)(ptr) + offset; \ |
| }) |
| |
| /* |
| * Binary search in the unwind index. The entries are |
| * guaranteed to be sorted in ascending order by the linker. |
| * |
| * start = first entry |
| * origin = first entry with positive offset (or stop if there is no such entry) |
| * stop - 1 = last entry |
| */ |
| static const struct unwind_idx *search_index(unsigned long addr, |
| const struct unwind_idx *start, |
| const struct unwind_idx *origin, |
| const struct unwind_idx *stop) |
| { |
| unsigned long addr_prel31; |
| |
| pr_debug("%s(%08lx, %p, %p, %p)\n", |
| __func__, addr, start, origin, stop); |
| |
| /* |
| * only search in the section with the matching sign. This way the |
| * prel31 numbers can be compared as unsigned longs. |
| */ |
| if (addr < (unsigned long)start) |
| /* negative offsets: [start; origin) */ |
| stop = origin; |
| else |
| /* positive offsets: [origin; stop) */ |
| start = origin; |
| |
| /* prel31 for address relavive to start */ |
| addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff; |
| |
| while (start < stop - 1) { |
| const struct unwind_idx *mid = start + ((stop - start) >> 1); |
| |
| /* |
| * As addr_prel31 is relative to start an offset is needed to |
| * make it relative to mid. |
| */ |
| if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) < |
| mid->addr_offset) |
| stop = mid; |
| else { |
| /* keep addr_prel31 relative to start */ |
| addr_prel31 -= ((unsigned long)mid - |
| (unsigned long)start); |
| start = mid; |
| } |
| } |
| |
| if (likely(start->addr_offset <= addr_prel31)) |
| return start; |
| else { |
| pr_warn("unwind: Unknown symbol address %08lx\n", addr); |
| return NULL; |
| } |
| } |
| |
| static const struct unwind_idx *unwind_find_origin( |
| const struct unwind_idx *start, const struct unwind_idx *stop) |
| { |
| pr_debug("%s(%p, %p)\n", __func__, start, stop); |
| while (start < stop) { |
| const struct unwind_idx *mid = start + ((stop - start) >> 1); |
| |
| if (mid->addr_offset >= 0x40000000) |
| /* negative offset */ |
| start = mid + 1; |
| else |
| /* positive offset */ |
| stop = mid; |
| } |
| pr_debug("%s -> %p\n", __func__, stop); |
| return stop; |
| } |
| |
| static const struct unwind_idx *unwind_find_idx(unsigned long addr) |
| { |
| const struct unwind_idx *idx = NULL; |
| unsigned long flags; |
| |
| pr_debug("%s(%08lx)\n", __func__, addr); |
| |
| if (core_kernel_text(addr)) { |
| if (unlikely(!__origin_unwind_idx)) |
| __origin_unwind_idx = |
| unwind_find_origin(__start_unwind_idx, |
| __stop_unwind_idx); |
| |
| /* main unwind table */ |
| idx = search_index(addr, __start_unwind_idx, |
| __origin_unwind_idx, |
| __stop_unwind_idx); |
| } else { |
| /* module unwind tables */ |
| struct unwind_table *table; |
| |
| spin_lock_irqsave(&unwind_lock, flags); |
| list_for_each_entry(table, &unwind_tables, list) { |
| if (addr >= table->begin_addr && |
| addr < table->end_addr) { |
| idx = search_index(addr, table->start, |
| table->origin, |
| table->stop); |
| /* Move-to-front to exploit common traces */ |
| list_move(&table->list, &unwind_tables); |
| break; |
| } |
| } |
| spin_unlock_irqrestore(&unwind_lock, flags); |
| } |
| |
| pr_debug("%s: idx = %p\n", __func__, idx); |
| return idx; |
| } |
| |
| static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl) |
| { |
| unsigned long ret; |
| |
| if (ctrl->entries <= 0) { |
| pr_warn("unwind: Corrupt unwind table\n"); |
| return 0; |
| } |
| |
| ret = (*ctrl->insn >> (ctrl->byte * 8)) & 0xff; |
| |
| if (ctrl->byte == 0) { |
| ctrl->insn++; |
| ctrl->entries--; |
| ctrl->byte = 3; |
| } else |
| ctrl->byte--; |
| |
| return ret; |
| } |
| |
| /* Before poping a register check whether it is feasible or not */ |
| static int unwind_pop_register(struct unwind_ctrl_block *ctrl, |
| unsigned long **vsp, unsigned int reg) |
| { |
| if (unlikely(ctrl->check_each_pop)) |
| if (*vsp >= (unsigned long *)ctrl->sp_high) |
| return -URC_FAILURE; |
| |
| ctrl->vrs[reg] = *(*vsp)++; |
| return URC_OK; |
| } |
| |
| /* Helper functions to execute the instructions */ |
| static int unwind_exec_pop_subset_r4_to_r13(struct unwind_ctrl_block *ctrl, |
| unsigned long mask) |
| { |
| unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; |
| int load_sp, reg = 4; |
| |
| load_sp = mask & (1 << (13 - 4)); |
| while (mask) { |
| if (mask & 1) |
| if (unwind_pop_register(ctrl, &vsp, reg)) |
| return -URC_FAILURE; |
| mask >>= 1; |
| reg++; |
| } |
| if (!load_sp) |
| ctrl->vrs[SP] = (unsigned long)vsp; |
| |
| return URC_OK; |
| } |
| |
| static int unwind_exec_pop_r4_to_rN(struct unwind_ctrl_block *ctrl, |
| unsigned long insn) |
| { |
| unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; |
| int reg; |
| |
| /* pop R4-R[4+bbb] */ |
| for (reg = 4; reg <= 4 + (insn & 7); reg++) |
| if (unwind_pop_register(ctrl, &vsp, reg)) |
| return -URC_FAILURE; |
| |
| if (insn & 0x8) |
| if (unwind_pop_register(ctrl, &vsp, 14)) |
| return -URC_FAILURE; |
| |
| ctrl->vrs[SP] = (unsigned long)vsp; |
| |
| return URC_OK; |
| } |
| |
| static int unwind_exec_pop_subset_r0_to_r3(struct unwind_ctrl_block *ctrl, |
| unsigned long mask) |
| { |
| unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; |
| int reg = 0; |
| |
| /* pop R0-R3 according to mask */ |
| while (mask) { |
| if (mask & 1) |
| if (unwind_pop_register(ctrl, &vsp, reg)) |
| return -URC_FAILURE; |
| mask >>= 1; |
| reg++; |
| } |
| ctrl->vrs[SP] = (unsigned long)vsp; |
| |
| return URC_OK; |
| } |
| |
| /* |
| * Execute the current unwind instruction. |
| */ |
| static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) |
| { |
| unsigned long insn = unwind_get_byte(ctrl); |
| int ret = URC_OK; |
| |
| pr_debug("%s: insn = %08lx\n", __func__, insn); |
| |
| if ((insn & 0xc0) == 0x00) |
| ctrl->vrs[SP] += ((insn & 0x3f) << 2) + 4; |
| else if ((insn & 0xc0) == 0x40) |
| ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4; |
| else if ((insn & 0xf0) == 0x80) { |
| unsigned long mask; |
| |
| insn = (insn << 8) | unwind_get_byte(ctrl); |
| mask = insn & 0x0fff; |
| if (mask == 0) { |
| pr_warn("unwind: 'Refuse to unwind' instruction %04lx\n", |
| insn); |
| return -URC_FAILURE; |
| } |
| |
| ret = unwind_exec_pop_subset_r4_to_r13(ctrl, mask); |
| if (ret) |
| goto error; |
| } else if ((insn & 0xf0) == 0x90 && |
| (insn & 0x0d) != 0x0d) |
| ctrl->vrs[SP] = ctrl->vrs[insn & 0x0f]; |
| else if ((insn & 0xf0) == 0xa0) { |
| ret = unwind_exec_pop_r4_to_rN(ctrl, insn); |
| if (ret) |
| goto error; |
| } else if (insn == 0xb0) { |
| if (ctrl->vrs[PC] == 0) |
| ctrl->vrs[PC] = ctrl->vrs[LR]; |
| /* no further processing */ |
| ctrl->entries = 0; |
| } else if (insn == 0xb1) { |
| unsigned long mask = unwind_get_byte(ctrl); |
| |
| if (mask == 0 || mask & 0xf0) { |
| pr_warn("unwind: Spare encoding %04lx\n", |
| (insn << 8) | mask); |
| return -URC_FAILURE; |
| } |
| |
| ret = unwind_exec_pop_subset_r0_to_r3(ctrl, mask); |
| if (ret) |
| goto error; |
| } else if (insn == 0xb2) { |
| unsigned long uleb128 = unwind_get_byte(ctrl); |
| |
| ctrl->vrs[SP] += 0x204 + (uleb128 << 2); |
| } else { |
| pr_warn("unwind: Unhandled instruction %02lx\n", insn); |
| return -URC_FAILURE; |
| } |
| |
| pr_debug("%s: fp = %08lx sp = %08lx lr = %08lx pc = %08lx\n", __func__, |
| ctrl->vrs[FP], ctrl->vrs[SP], ctrl->vrs[LR], ctrl->vrs[PC]); |
| |
| error: |
| return ret; |
| } |
| |
| /* |
| * Unwind a single frame starting with *sp for the symbol at *pc. It |
| * updates the *pc and *sp with the new values. |
| */ |
| int unwind_frame(struct stackframe *frame) |
| { |
| unsigned long low; |
| const struct unwind_idx *idx; |
| struct unwind_ctrl_block ctrl; |
| |
| /* store the highest address on the stack to avoid crossing it*/ |
| low = frame->sp; |
| ctrl.sp_high = ALIGN(low, THREAD_SIZE); |
| |
| pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__, |
| frame->pc, frame->lr, frame->sp); |
| |
| if (!kernel_text_address(frame->pc)) |
| return -URC_FAILURE; |
| |
| idx = unwind_find_idx(frame->pc); |
| if (!idx) { |
| pr_warn("unwind: Index not found %08lx\n", frame->pc); |
| return -URC_FAILURE; |
| } |
| |
| ctrl.vrs[FP] = frame->fp; |
| ctrl.vrs[SP] = frame->sp; |
| ctrl.vrs[LR] = frame->lr; |
| ctrl.vrs[PC] = 0; |
| |
| if (idx->insn == 1) |
| /* can't unwind */ |
| return -URC_FAILURE; |
| else if ((idx->insn & 0x80000000) == 0) |
| /* prel31 to the unwind table */ |
| ctrl.insn = (unsigned long *)prel31_to_addr(&idx->insn); |
| else if ((idx->insn & 0xff000000) == 0x80000000) |
| /* only personality routine 0 supported in the index */ |
| ctrl.insn = &idx->insn; |
| else { |
| pr_warn("unwind: Unsupported personality routine %08lx in the index at %p\n", |
| idx->insn, idx); |
| return -URC_FAILURE; |
| } |
| |
| /* check the personality routine */ |
| if ((*ctrl.insn & 0xff000000) == 0x80000000) { |
| ctrl.byte = 2; |
| ctrl.entries = 1; |
| } else if ((*ctrl.insn & 0xff000000) == 0x81000000) { |
| ctrl.byte = 1; |
| ctrl.entries = 1 + ((*ctrl.insn & 0x00ff0000) >> 16); |
| } else { |
| pr_warn("unwind: Unsupported personality routine %08lx at %p\n", |
| *ctrl.insn, ctrl.insn); |
| return -URC_FAILURE; |
| } |
| |
| ctrl.check_each_pop = 0; |
| |
| while (ctrl.entries > 0) { |
| int urc; |
| if ((ctrl.sp_high - ctrl.vrs[SP]) < sizeof(ctrl.vrs)) |
| ctrl.check_each_pop = 1; |
| urc = unwind_exec_insn(&ctrl); |
| if (urc < 0) |
| return urc; |
| if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high) |
| return -URC_FAILURE; |
| } |
| |
| if (ctrl.vrs[PC] == 0) |
| ctrl.vrs[PC] = ctrl.vrs[LR]; |
| |
| /* check for infinite loop */ |
| if (frame->pc == ctrl.vrs[PC]) |
| return -URC_FAILURE; |
| |
| frame->fp = ctrl.vrs[FP]; |
| frame->sp = ctrl.vrs[SP]; |
| frame->lr = ctrl.vrs[LR]; |
| frame->pc = ctrl.vrs[PC]; |
| |
| return URC_OK; |
| } |
| |
| void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk) |
| { |
| struct stackframe frame; |
| register unsigned long current_sp asm ("sp"); |
| |
| pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk); |
| |
| if (!tsk) |
| tsk = current; |
| |
| if (regs) { |
| arm_get_current_stackframe(regs, &frame); |
| /* PC might be corrupted, use LR in that case. */ |
| if (!kernel_text_address(regs->ARM_pc)) |
| frame.pc = regs->ARM_lr; |
| } else if (tsk == current) { |
| frame.fp = (unsigned long)__builtin_frame_address(0); |
| frame.sp = current_sp; |
| frame.lr = (unsigned long)__builtin_return_address(0); |
| frame.pc = (unsigned long)unwind_backtrace; |
| } else { |
| /* task blocked in __switch_to */ |
| frame.fp = thread_saved_fp(tsk); |
| frame.sp = thread_saved_sp(tsk); |
| /* |
| * The function calling __switch_to cannot be a leaf function |
| * so LR is recovered from the stack. |
| */ |
| frame.lr = 0; |
| frame.pc = thread_saved_pc(tsk); |
| } |
| |
| while (1) { |
| int urc; |
| unsigned long where = frame.pc; |
| |
| urc = unwind_frame(&frame); |
| if (urc < 0) |
| break; |
| dump_backtrace_entry(where, frame.pc, frame.sp - 4); |
| } |
| } |
| |
| struct unwind_table *unwind_table_add(unsigned long start, unsigned long size, |
| unsigned long text_addr, |
| unsigned long text_size) |
| { |
| unsigned long flags; |
| struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL); |
| |
| pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size, |
| text_addr, text_size); |
| |
| if (!tab) |
| return tab; |
| |
| tab->start = (const struct unwind_idx *)start; |
| tab->stop = (const struct unwind_idx *)(start + size); |
| tab->origin = unwind_find_origin(tab->start, tab->stop); |
| tab->begin_addr = text_addr; |
| tab->end_addr = text_addr + text_size; |
| |
| spin_lock_irqsave(&unwind_lock, flags); |
| list_add_tail(&tab->list, &unwind_tables); |
| spin_unlock_irqrestore(&unwind_lock, flags); |
| |
| return tab; |
| } |
| |
| void unwind_table_del(struct unwind_table *tab) |
| { |
| unsigned long flags; |
| |
| if (!tab) |
| return; |
| |
| spin_lock_irqsave(&unwind_lock, flags); |
| list_del(&tab->list); |
| spin_unlock_irqrestore(&unwind_lock, flags); |
| |
| kfree(tab); |
| } |