| Message ID | 1414219373-20070-4-git-send-email-wangnan0@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 2014-10-25 at 14:42 +0800, Wang Nan wrote: > 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 <wangnan0@huawei.com> My comments below are mostly minor nit-picks, but there is one bug and some code clarity issues. > --- > 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 Wouldn't it be cleaner, i.e. avoid this extra #ifdef, to define the the kprobe checker tables in kprobes-{arm,thumb}.c and corresponding headers? That is the same as the action tables are. > 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}, The above PROBES_STRD should be PROBES_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, Should the function name not be chk_stack_t32_str? The use of 'check' in the name isn't consistent with the other functions and seems redundant considering that's what the 'chk' at the start means. > + 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); Best use REG_TYPE_NONE rather than 0 > + rn = (insn & 0xf0000) >> 16; > + if ((regs & 0xf) != 0) Again, REG_TYPE_NONE rather than 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) The latest ARM ARM says "ARMv8-A removes UNPREDICTABLE for R13" so I think it would be safest to also include a test for rm != 0xd. Even though at the moment the decode table prevents this situation occurring, I can imaging it being something that could get overlooked in any later changes to support ARMv8. > + 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; Why test ubit? We (and the compiler) know it's zero. Also, we can avoid an extra ? operator if we return for rn == 0xd, so how about the above function more simply written like... /* If stmi? or not using SP then doesn't require extra stack */ if (ubit || rn != 0xd) return INSN_GOOD; /* If pbit == 0, this is stmda, one word is saved */ asi->stack_space = (hweight32(reglist) - !pbit) * 4 Note, I also changed 'dword' to 'word' as this is ARM not X86 :-) > + 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; I'm wondering what the convention for setting stack_space is. If we initialise it to zero here, I guess it means that checker functions don't need to change it unless they detect stack use? In which case, check_insn_stack_regs doesn't need to zero it at it's start. However, if we think that it is best for stack checker functions to always set stack_space (not sure I do) then this is missing from chk_stack_stm and chk_stack_t32_check_str. > + > 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, I can't work out why the name ends with '_regs' ? Would something like check_insn_stack_use be better? > + 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. The word 'be' is missing from last sentence, it should read "Rm may be 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>' */ The above instruction type can't cause us to get here because we earlier return for !index (and if it could get here, the test below for 'add' doesn't catch the -<imm> case). > + /* 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, I think the word 'STORE' can be misleading, "str r0, [sp,#4]" could be regarded as a stack store, or if what we mean is update SP, then "sub sp,sp,#N" does that and allocates stack space, neither of those is what we're testing for. How about using the term 'stack use'? So the enum names could become STACK_USE_NONE, /* or NO_STACK_USE if preferred */ STACK_USE_REG, STACK_USE_IMM, > + 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
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
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 <wangnan0@huawei.com> --- 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(-)