[PATCH v6 4/7] ARM: kprobes: collects stack consumption for store instructions
From: Wang Nan
Date: Wed Oct 22 2014 - 07:34:15 EST
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@xxxxxxxxxx>
---
arch/arm/include/asm/probes.h | 1 +
arch/arm/kernel/kprobes-arm.c | 8 ++---
arch/arm/kernel/kprobes-thumb.c | 8 ++---
arch/arm/kernel/probes-arm.c | 19 +++++++++++
arch/arm/kernel/probes-arm.h | 7 +++++
arch/arm/kernel/probes-thumb.c | 70 +++++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/probes-thumb.h | 9 ++++++
arch/arm/kernel/probes.c | 64 +++++++++++++++++++++++++++++++++++++
arch/arm/kernel/probes.h | 13 ++++++++
arch/arm/kernel/uprobes-arm.c | 8 ++---
10 files changed, 195 insertions(+), 12 deletions(-)
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-arm.c b/arch/arm/kernel/kprobes-arm.c
index 1094ff1..bb1bec3 100644
--- a/arch/arm/kernel/kprobes-arm.c
+++ b/arch/arm/kernel/kprobes-arm.c
@@ -316,11 +316,11 @@ const struct decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = {
[PROBES_MUL2] = {.handler = emulate_rd16rn12rm0rs8_rwflags_nopc},
[PROBES_SWP] = {.handler = emulate_rd12rn16rm0_rwflags_nopc},
[PROBES_LDRD] = {.handler = emulate_ldrdstrd},
- [PROBES_STRD] = {.handler = emulate_ldrdstrd},
+ [PROBES_STRD] = {.checker = probes_check_arm_store_extra, .handler = emulate_ldrdstrd},
[PROBES_LOAD_EXTRA] = {.handler = emulate_ldr},
[PROBES_LOAD] = {.handler = emulate_ldr},
- [PROBES_STORE_EXTRA] = {.handler = emulate_str},
- [PROBES_STORE] = {.handler = emulate_str},
+ [PROBES_STORE_EXTRA] = {.checker = probes_check_arm_store_extra, .handler = emulate_str},
+ [PROBES_STORE] = {.checker = probes_check_arm_store, .handler = emulate_str},
[PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
[PROBES_DATA_PROCESSING_REG] = {
.handler = emulate_rd12rn16rm0rs8_rwflags},
@@ -341,5 +341,5 @@ const struct decode_action kprobes_arm_actions[NUM_PROBES_ARM_ACTIONS] = {
[PROBES_BITFIELD] = {.handler = emulate_rd12rm0_noflags_nopc},
[PROBES_BRANCH] = {.handler = simulate_bbl},
[PROBES_LDM] = {.decoder = kprobe_decode_ldmstm},
- [PROBES_STM] = {.decoder = kprobe_decode_ldmstm},
+ [PROBES_STM] = {.checker = probes_check_stm, .decoder = kprobe_decode_ldmstm},
};
diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c
index c6426b6..5da4231 100644
--- a/arch/arm/kernel/kprobes-thumb.c
+++ b/arch/arm/kernel/kprobes-thumb.c
@@ -615,7 +615,7 @@ const struct decode_action kprobes_t16_actions[NUM_PROBES_T16_ACTIONS] = {
[PROBES_T16_ADD_SP] = {.handler = t16_simulate_add_sp_imm},
[PROBES_T16_CBZ] = {.handler = t16_simulate_cbz},
[PROBES_T16_SIGN_EXTEND] = {.handler = t16_emulate_loregs_rwflags},
- [PROBES_T16_PUSH] = {.decoder = t16_decode_push},
+ [PROBES_T16_PUSH] = {.checker = t16_check_push, .decoder = t16_decode_push},
[PROBES_T16_POP] = {.decoder = t16_decode_pop},
[PROBES_T16_SEV] = {.handler = probes_emulate_none},
[PROBES_T16_WFE] = {.handler = probes_simulate_nop},
@@ -639,9 +639,9 @@ const struct decode_action kprobes_t16_actions[NUM_PROBES_T16_ACTIONS] = {
const struct decode_action kprobes_t32_actions[NUM_PROBES_T32_ACTIONS] = {
[PROBES_T32_LDM] = {.decoder = t32_decode_ldmstm},
- [PROBES_T32_STM] = {.decoder = t32_decode_ldmstm},
+ [PROBES_T32_STM] = {.checker = probes_check_stm, .decoder = t32_decode_ldmstm},
[PROBES_T32_LDRD] = {.handler = t32_emulate_ldrdstrd},
- [PROBES_T32_STRD] = {.handler = t32_emulate_ldrdstrd},
+ [PROBES_T32_STRD] = {.checker = t32_check_strd, .handler = t32_emulate_ldrdstrd},
[PROBES_T32_TABLE_BRANCH] = {.handler = t32_simulate_table_branch},
[PROBES_T32_TST] = {.handler = t32_emulate_rd8rn16rm0_rwflags},
[PROBES_T32_MOV] = {.handler = t32_emulate_rd8rn16rm0_rwflags},
@@ -661,7 +661,7 @@ const struct decode_action kprobes_t32_actions[NUM_PROBES_T32_ACTIONS] = {
[PROBES_T32_PLDI] = {.handler = probes_simulate_nop},
[PROBES_T32_LDR_LIT] = {.handler = t32_simulate_ldr_literal},
[PROBES_T32_LDR] = {.handler = t32_emulate_ldrstr},
- [PROBES_T32_STR] = {.handler = t32_emulate_ldrstr},
+ [PROBES_T32_STR] = {.checker = t32_check_str, .handler = t32_emulate_ldrstr},
[PROBES_T32_SIGN_EXTEND] = {.handler = t32_emulate_rd8rn16rm0_rwflags},
[PROBES_T32_MEDIA] = {.handler = t32_emulate_rd8rn16rm0_rwflags},
[PROBES_T32_REVERSE] = {.handler = t32_emulate_rd8rn16_noflags},
diff --git a/arch/arm/kernel/probes-arm.c b/arch/arm/kernel/probes-arm.c
index 148153e..90d2f29 100644
--- a/arch/arm/kernel/probes-arm.c
+++ b/arch/arm/kernel/probes-arm.c
@@ -109,6 +109,25 @@ void __kprobes simulate_mov_ipsp(probes_opcode_t insn,
regs->uregs[12] = regs->uregs[13];
}
+enum probes_insn __kprobes probes_check_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 probes_check_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;
+}
+
+
/*
* 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 18ffc9a..d0ad9a4 100644
--- a/arch/arm/kernel/probes-arm.h
+++ b/arch/arm/kernel/probes-arm.h
@@ -66,6 +66,13 @@ void __kprobes simulate_mrs(probes_opcode_t opcode,
void __kprobes simulate_mov_ipsp(probes_opcode_t opcode,
struct arch_probes_insn *asi, struct pt_regs *regs);
+enum probes_insn __kprobes probes_check_arm_store(probes_opcode_t,
+ struct arch_probes_insn *,
+ const struct decode_header *);
+enum probes_insn __kprobes probes_check_arm_store_extra(probes_opcode_t,
+ struct arch_probes_insn *,
+ const struct decode_header *);
+
extern const union decode_item probes_decode_arm_table[];
enum probes_insn arm_probes_decode_insn(probes_opcode_t,
diff --git a/arch/arm/kernel/probes-thumb.c b/arch/arm/kernel/probes-thumb.c
index 749d4cd..5d0c936 100644
--- a/arch/arm/kernel/probes-thumb.c
+++ b/arch/arm/kernel/probes-thumb.c
@@ -15,6 +15,76 @@
#include "probes.h"
#include "probes-thumb.h"
+enum probes_insn __kprobes t32_check_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 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 t16_check_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;
+}
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 a9c65c9..f908b12 100644
--- a/arch/arm/kernel/probes-thumb.h
+++ b/arch/arm/kernel/probes-thumb.h
@@ -100,4 +100,13 @@ enum probes_insn __kprobes
thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool emulate, const struct decode_action *actions);
+enum probes_insn __kprobes t32_check_strd(probes_opcode_t insn,
+ struct arch_probes_insn *asi,
+ const struct decode_header *h);
+enum probes_insn __kprobes t32_check_str(probes_opcode_t insn,
+ struct arch_probes_insn *asi,
+ const struct decode_header *h);
+enum probes_insn __kprobes t16_check_push(probes_opcode_t insn,
+ struct arch_probes_insn *asi,
+ const struct decode_header *h);
#endif
diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c
index 6164b4d..8428fe8 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 probes_check_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
@@ -395,6 +414,8 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
bool matched = false;
probes_opcode_t origin_insn = insn;
+ asi->stack_space = 0;
+
if (emulate)
insn = prepare_emulated_insn(insn, asi, thumb);
@@ -464,3 +485,46 @@ 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 c56dd3d..4c0a04a 100644
--- a/arch/arm/kernel/probes.h
+++ b/arch/arm/kernel/probes.h
@@ -410,4 +410,17 @@ probes_decode_insn(probes_opcode_t insn, struct arch_probes_insn *asi,
const union decode_item *table, bool thumb, bool emulate,
const struct decode_action *actions);
+enum probes_insn __kprobes probes_check_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
diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c
index 0a8caa3..1da524d 100644
--- a/arch/arm/kernel/uprobes-arm.c
+++ b/arch/arm/kernel/uprobes-arm.c
@@ -208,11 +208,11 @@ const struct decode_action uprobes_probes_actions[] = {
[PROBES_MUL2] = {.handler = probes_simulate_nop},
[PROBES_SWP] = {.handler = probes_simulate_nop},
[PROBES_LDRD] = {.decoder = decode_pc_ro},
- [PROBES_STRD] = {.decoder = decode_pc_ro},
+ [PROBES_STRD] = {.checker = probes_check_arm_store_extra, .decoder = decode_pc_ro},
[PROBES_LOAD_EXTRA] = {.decoder = decode_pc_ro},
[PROBES_LOAD] = {.decoder = decode_ldr},
- [PROBES_STORE_EXTRA] = {.decoder = decode_pc_ro},
- [PROBES_STORE] = {.decoder = decode_pc_ro},
+ [PROBES_STORE_EXTRA] = {.checker = probes_check_arm_store_extra, .decoder = decode_pc_ro},
+ [PROBES_STORE] = {.checker = probes_check_arm_store, .decoder = decode_pc_ro},
[PROBES_MOV_IP_SP] = {.handler = simulate_mov_ipsp},
[PROBES_DATA_PROCESSING_REG] = {
.decoder = decode_rd12rn16rm0rs8_rwflags},
@@ -232,5 +232,5 @@ const struct decode_action uprobes_probes_actions[] = {
[PROBES_BITFIELD] = {.handler = probes_simulate_nop},
[PROBES_BRANCH] = {.handler = simulate_bbl},
[PROBES_LDM] = {.decoder = uprobe_decode_ldmstm},
- [PROBES_STM] = {.decoder = uprobe_decode_ldmstm}
+ [PROBES_STM] = {.checker = probes_check_stm, .decoder = uprobe_decode_ldmstm}
};
--
1.8.4
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