diff options
Diffstat (limited to 'arch/arm/kernel/unwind.c')
| -rw-r--r-- | arch/arm/kernel/unwind.c | 137 |
1 files changed, 100 insertions, 37 deletions
diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c index 00df012c4678..3c217694ebec 100644 --- a/arch/arm/kernel/unwind.c +++ b/arch/arm/kernel/unwind.c @@ -68,6 +68,12 @@ 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 */ }; @@ -235,12 +241,85 @@ static unsigned long unwind_get_byte(struct unwind_ctrl_block *ctrl) 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 & 0x80) + 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); @@ -250,8 +329,6 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) ctrl->vrs[SP] -= ((insn & 0x3f) << 2) + 4; else if ((insn & 0xf0) == 0x80) { unsigned long mask; - unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; - int load_sp, reg = 4; insn = (insn << 8) | unwind_get_byte(ctrl); mask = insn & 0x0fff; @@ -261,29 +338,16 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) return -URC_FAILURE; } - /* pop R4-R15 according to mask */ - load_sp = mask & (1 << (13 - 4)); - while (mask) { - if (mask & 1) - ctrl->vrs[reg] = *vsp++; - mask >>= 1; - reg++; - } - if (!load_sp) - ctrl->vrs[SP] = (unsigned long)vsp; + 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) { - unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; - int reg; - - /* pop R4-R[4+bbb] */ - for (reg = 4; reg <= 4 + (insn & 7); reg++) - ctrl->vrs[reg] = *vsp++; - if (insn & 0x80) - ctrl->vrs[14] = *vsp++; - ctrl->vrs[SP] = (unsigned long)vsp; + 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]; @@ -291,8 +355,6 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) ctrl->entries = 0; } else if (insn == 0xb1) { unsigned long mask = unwind_get_byte(ctrl); - unsigned long *vsp = (unsigned long *)ctrl->vrs[SP]; - int reg = 0; if (mask == 0 || mask & 0xf0) { pr_warning("unwind: Spare encoding %04lx\n", @@ -300,14 +362,9 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) return -URC_FAILURE; } - /* pop R0-R3 according to mask */ - while (mask) { - if (mask & 1) - ctrl->vrs[reg] = *vsp++; - mask >>= 1; - reg++; - } - ctrl->vrs[SP] = (unsigned long)vsp; + 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); @@ -320,7 +377,8 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) 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]); - return URC_OK; +error: + return ret; } /* @@ -329,13 +387,13 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl) */ int unwind_frame(struct stackframe *frame) { - unsigned long high, low; + unsigned long low; const struct unwind_idx *idx; struct unwind_ctrl_block ctrl; - /* only go to a higher address on the stack */ + /* store the highest address on the stack to avoid crossing it*/ low = frame->sp; - high = ALIGN(low, THREAD_SIZE); + ctrl.sp_high = ALIGN(low, THREAD_SIZE); pr_debug("%s(pc = %08lx lr = %08lx sp = %08lx)\n", __func__, frame->pc, frame->lr, frame->sp); @@ -382,11 +440,16 @@ int unwind_frame(struct stackframe *frame) return -URC_FAILURE; } + ctrl.check_each_pop = 0; + while (ctrl.entries > 0) { - int urc = unwind_exec_insn(&ctrl); + 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] >= high) + if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= ctrl.sp_high) return -URC_FAILURE; } |