This patch use previous introduced checker on store instructions, record stack consumption informations to arch_probes_insn. With such information, kprobe opt can decide how much stack needs to be protected.
Signed-off-by: Wang Nan <[email protected]> --- arch/arm/include/asm/probes.h | 1 + arch/arm/kernel/kprobes.c | 15 +++++++- arch/arm/kernel/probes-arm.c | 25 +++++++++++++ arch/arm/kernel/probes-arm.h | 1 + arch/arm/kernel/probes-thumb.c | 80 ++++++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/probes-thumb.h | 2 ++ arch/arm/kernel/probes.c | 64 +++++++++++++++++++++++++++++++++ arch/arm/kernel/probes.h | 13 +++++++ 8 files changed, 200 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/probes.h b/arch/arm/include/asm/probes.h index 806cfe6..ccf9af3 100644 --- a/arch/arm/include/asm/probes.h +++ b/arch/arm/include/asm/probes.h @@ -38,6 +38,7 @@ struct arch_probes_insn { probes_check_cc *insn_check_cc; probes_insn_singlestep_t *insn_singlestep; probes_insn_fn_t *insn_fn; + int stack_space; }; #endif diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c index 3302983..618531d 100644 --- a/arch/arm/kernel/kprobes.c +++ b/arch/arm/kernel/kprobes.c @@ -61,6 +61,16 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) kprobe_decode_insn_t *decode_insn; const union decode_action *actions; int is; + const struct decode_checker **checkers; +#ifdef CONFIG_THUMB2_KERNEL + const struct decode_checker *t32_checkers[] = + {t32_stack_checker, NULL}; + const struct decode_checker *t16_checkers[] = + {t16_stack_checker, NULL}; +#else + const struct decode_checker *arm_checkers[] = + {arm_stack_checker, NULL}; +#endif if (in_exception_text(addr)) return -EINVAL; @@ -74,9 +84,11 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) insn = __opcode_thumb32_compose(insn, inst2); decode_insn = thumb32_probes_decode_insn; actions = kprobes_t32_actions; + checkers = t32_checkers; } else { decode_insn = thumb16_probes_decode_insn; actions = kprobes_t16_actions; + checkers = t16_checkers; } #else /* !CONFIG_THUMB2_KERNEL */ thumb = false; @@ -85,12 +97,13 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) insn = __mem_to_opcode_arm(*p->addr); decode_insn = arm_probes_decode_insn; actions = kprobes_arm_actions; + checkers = arm_checkers; #endif p->opcode = insn; p->ainsn.insn = tmp_insn; - switch ((*decode_insn)(insn, &p->ainsn, true, actions, NULL)) { + switch ((*decode_insn)(insn, &p->ainsn, true, actions, checkers)) { case INSN_REJECTED: /* not supported */ return -EINVAL; diff --git a/arch/arm/kernel/probes-arm.c b/arch/arm/kernel/probes-arm.c index d280e825..20e95c0 100644 --- a/arch/arm/kernel/probes-arm.c +++ b/arch/arm/kernel/probes-arm.c @@ -109,6 +109,31 @@ void __kprobes simulate_mov_ipsp(probes_opcode_t insn, regs->uregs[12] = regs->uregs[13]; } +enum probes_insn __kprobes chk_stack_arm_store(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int imm = insn & 0xfff; + check_insn_stack_regs(insn, asi, h, imm); + return INSN_GOOD; +} + +enum probes_insn __kprobes chk_stack_arm_store_extra(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int imm = ((insn & 0xf00) >> 4) + (insn & 0xf); + check_insn_stack_regs(insn, asi, h, imm); + return INSN_GOOD; +} + +const struct decode_checker arm_stack_checker[NUM_PROBES_ARM_ACTIONS] = { + [PROBES_STRD] = {.checker = chk_stack_arm_store_extra}, + [PROBES_STORE_EXTRA] = {.checker = chk_stack_arm_store_extra}, + [PROBES_STRD] = {.checker = chk_stack_arm_store}, + [PROBES_STM] = {.checker = chk_stack_stm}, +}; + /* * For the instruction masking and comparisons in all the "space_*" * functions below, Do _not_ rearrange the order of tests unless diff --git a/arch/arm/kernel/probes-arm.h b/arch/arm/kernel/probes-arm.h index 185adaf..4d63cf8 100644 --- a/arch/arm/kernel/probes-arm.h +++ b/arch/arm/kernel/probes-arm.h @@ -73,4 +73,5 @@ enum probes_insn arm_probes_decode_insn(probes_opcode_t, const union decode_action *actions, const struct decode_checker *checkers[]); +extern const struct decode_checker arm_stack_checker[]; #endif diff --git a/arch/arm/kernel/probes-thumb.c b/arch/arm/kernel/probes-thumb.c index 56925e4..8e7c5be 100644 --- a/arch/arm/kernel/probes-thumb.c +++ b/arch/arm/kernel/probes-thumb.c @@ -15,6 +15,86 @@ #include "probes.h" #include "probes-thumb.h" +enum probes_insn __kprobes chk_stack_t32_strd(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int imm = insn & 0xff; + check_insn_stack_regs(insn, asi, h, imm); + return INSN_GOOD; +} + +/* + * Note: This function doesn't process PROBES_T32_STRD. + */ +enum probes_insn __kprobes chk_stack_t32_check_str(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + int rn = -1, rm = -1; + u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; + int index, add; + + /* Rn is used in every cases */ + BUG_ON((regs & 0xf0000) == 0); + rn = (insn & 0xf0000) >> 16; + if ((regs & 0xf) != 0) + rm = insn & 0xf; + + /* + * Rn is not SP. Rm can't be sp in any case. + * So it is not a stack store. + */ + if (rn != 0xd) + return INSN_GOOD; + + /* + * For 'str? rx, [sp, ry]', ry can be negative. In addition, + * index is true in every cases, so unable to determine stack + * consumption. + */ + if (rm != -1) { + asi->stack_space = -1; + return INSN_GOOD; + } + + /* + * For 'str? rx, [sp, #+/-<imm>]', if bit 23 is set, index + * and add are both set. Else, index and add are determined + * by P bit and U bit (bit 10, 9) + */ + if (insn & 0x800000) + index = add = 1; + else { + index = (insn & (1 << 10)); + add = (insn &(1 << 9)); + } + + if (!index || add) + return INSN_GOOD; + + asi->stack_space = insn & 0xff; + return INSN_GOOD; +} + +enum probes_insn __kprobes chk_stack_t16_push(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + unsigned int reglist = insn & 0x1ff; + asi->stack_space = hweight32(reglist) * 4; + return INSN_GOOD; +} + +const struct decode_checker t32_stack_checker[NUM_PROBES_T32_ACTIONS] = { + [PROBES_T32_STM] = {.checker = chk_stack_stm}, + [PROBES_T32_STRD] = {.checker = chk_stack_t32_strd}, + [PROBES_T32_STR] = {.checker = chk_stack_t32_check_str}, +}; + +const struct decode_checker t16_stack_checker[NUM_PROBES_T16_ACTIONS] = { + [PROBES_T16_PUSH] = {.checker = chk_stack_t16_push}, +}; static const union decode_item t32_table_1110_100x_x0xx[] = { /* Load/store multiple instructions */ diff --git a/arch/arm/kernel/probes-thumb.h b/arch/arm/kernel/probes-thumb.h index 2277744..a5783d0 100644 --- a/arch/arm/kernel/probes-thumb.h +++ b/arch/arm/kernel/probes-thumb.h @@ -102,4 +102,6 @@ thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, bool emulate, const union decode_action *actions, const struct decode_checker *checkers[]); +extern const struct decode_checker t32_stack_checker[]; +extern const struct decode_checker t16_stack_checker[]; #endif diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c index 02598da..4ef4087 100644 --- a/arch/arm/kernel/probes.c +++ b/arch/arm/kernel/probes.c @@ -188,6 +188,25 @@ void __kprobes probes_emulate_none(probes_opcode_t opcode, asi->insn_fn(); } +/* ARM and Thumb can share this checker */ +enum probes_insn __kprobes chk_stack_stm(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h) +{ + unsigned int reglist = insn & 0xffff; + int ubit = insn & (1 << 23); + int pbit = insn & (1 << 24); + int rn = (insn >> 16) & 0xf; + + /* This is stmi?, doesn't require extra stack */ + if (ubit) + return INSN_GOOD; + /* If pbit == ubit (== 0), this is stmda, one dword is saved */ + asi->stack_space = (rn == 0xd) ? + (hweight32(reglist) - ((!pbit == !ubit) ? 1 : 0)) * 4 : 0; + return INSN_GOOD; +} + /* * Prepare an instruction slot to receive an instruction for emulating. * This is done by placing a subroutine return after the location where the @@ -425,6 +444,8 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, */ probes_opcode_t origin_insn = insn; + asi->stack_space = 0; + if (emulate) insn = prepare_emulated_insn(insn, asi, thumb); @@ -503,3 +524,46 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, } } } + +int __kprobes check_insn_stack_regs(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h, + int imm) +{ + u32 regs = h->type_regs.bits >> DECODE_TYPE_BITS; + int rn = -1, rm = -1, index, add; + asi->stack_space = 0; + + if (((regs >> 16) & 0xf) != REG_TYPE_NONE) + rn = (insn >> 16) & 0xf; + + if ((regs & 0xf) != REG_TYPE_NONE) + rm = insn & 0xf; + + if ((rn != 13) && (rm != 13)) + return NOT_STACK_STORE; + + index = insn & (1 << 24); + add = insn & (1 << 23); + + if (!index) + return NOT_STACK_STORE; + + /* + * Even if insn is 'str r0, [sp], +<Rm>', Rm may less than 0. + * Therefore if both Rn and Rm are registers and !index, + * We are unable to determine whether it is a stack store. + */ + if ((rn != -1) && (rm != -1)) { + asi->stack_space = -1; + return STACK_REG; + } + + /* 'str(d/h) r0, [sp], #+/-<imm>' */ + /* or 'str(d/h) r0, [sp, #+<imm>'] */ + if (add) + return NOT_STACK_STORE; + + asi->stack_space = imm; + return STACK_IMM; +} diff --git a/arch/arm/kernel/probes.h b/arch/arm/kernel/probes.h index b4bf1f5..b52629c 100644 --- a/arch/arm/kernel/probes.h +++ b/arch/arm/kernel/probes.h @@ -413,4 +413,17 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi, const union decode_action *actions, const struct decode_checker **checkers); +enum probes_insn __kprobes chk_stack_stm(probes_opcode_t, + struct arch_probes_insn *, + const struct decode_header *); + +enum { + NOT_STACK_STORE, + STACK_REG, + STACK_IMM, +}; +int __kprobes check_insn_stack_regs(probes_opcode_t insn, + struct arch_probes_insn *asi, + const struct decode_header *h, + int imm); #endif -- 1.8.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
