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Subject[PATCH v4 13/16] ARM: Add an emulate flag to the kprobes/uprobes instruction decode functions
Date
From: "David A. Long" <dave.long@linaro.org>

Add an emulate flag into the instruction interpreter, primarily for uprobes
support.

Signed-off-by: David A. Long <dave.long@linaro.org>
---
arch/arm/kernel/kprobes.c | 3 ++-
arch/arm/kernel/kprobes.h | 1 +
arch/arm/kernel/probes-arm.c | 4 ++--
arch/arm/kernel/probes-arm.h | 2 +-
arch/arm/kernel/probes-thumb.c | 8 ++++----
arch/arm/kernel/probes-thumb.h | 4 ++--
arch/arm/kernel/probes.c | 32 +++++++++++++++++++++++---------
arch/arm/kernel/probes.h | 2 +-
8 files changed, 36 insertions(+), 20 deletions(-)

diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index 0d9d49b..04690f9 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -87,7 +87,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
p->opcode = insn;
p->ainsn.insn = tmp_insn;

- switch ((*decode_insn)(insn, &p->ainsn, actions)) {
+ switch ((*decode_insn)(insn, &p->ainsn,
+ true, actions)) {
case INSN_REJECTED: /* not supported */
return -EINVAL;

diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h
index e1305a8..580d82c 100644
--- a/arch/arm/kernel/kprobes.h
+++ b/arch/arm/kernel/kprobes.h
@@ -35,6 +35,7 @@ kprobe_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi,

typedef enum probes_insn (kprobe_decode_insn_t)(kprobe_opcode_t,
struct arch_specific_insn *,
+ bool,
const union decode_item *);

#ifdef CONFIG_THUMB2_KERNEL
diff --git a/arch/arm/kernel/probes-arm.c b/arch/arm/kernel/probes-arm.c
index a44c3ad..01e99f7 100644
--- a/arch/arm/kernel/probes-arm.c
+++ b/arch/arm/kernel/probes-arm.c
@@ -723,10 +723,10 @@ static void __kprobes arm_singlestep(probes_opcode_t insn,
*/
enum probes_insn __kprobes
arm_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *actions)
+ bool emulate, const union decode_item *actions)
{
asi->insn_singlestep = arm_singlestep;
asi->insn_check_cc = probes_condition_checks[insn>>28];
return probes_decode_insn(insn, asi, probes_decode_arm_table, false,
- actions);
+ emulate, actions);
}
diff --git a/arch/arm/kernel/probes-arm.h b/arch/arm/kernel/probes-arm.h
index 7f81199..904033c 100644
--- a/arch/arm/kernel/probes-arm.h
+++ b/arch/arm/kernel/probes-arm.h
@@ -66,7 +66,7 @@ void __kprobes simulate_mov_ipsp(probes_opcode_t opcode,
extern const union decode_item probes_decode_arm_table[];

enum probes_insn arm_probes_decode_insn(probes_opcode_t,
- struct arch_specific_insn *,
+ struct arch_specific_insn *, bool emulate,
const union decode_item *actions);

#endif
diff --git a/arch/arm/kernel/probes-thumb.c b/arch/arm/kernel/probes-thumb.c
index 3f250e9..2ad0880 100644
--- a/arch/arm/kernel/probes-thumb.c
+++ b/arch/arm/kernel/probes-thumb.c
@@ -861,20 +861,20 @@ static void __kprobes thumb32_singlestep(probes_opcode_t opcode,

enum probes_insn __kprobes
thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *actions)
+ bool emulate, const union decode_item *actions)
{
asi->insn_singlestep = thumb16_singlestep;
asi->insn_check_cc = thumb_check_cc;
return probes_decode_insn(insn, asi, probes_decode_thumb16_table, true,
- actions);
+ emulate, actions);
}

enum probes_insn __kprobes
thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *actions)
+ bool emulate, const union decode_item *actions)
{
asi->insn_singlestep = thumb32_singlestep;
asi->insn_check_cc = thumb_check_cc;
return probes_decode_insn(insn, asi, probes_decode_thumb32_table, true,
- actions);
+ emulate, actions);
}
diff --git a/arch/arm/kernel/probes-thumb.h b/arch/arm/kernel/probes-thumb.h
index 556f067..78be667 100644
--- a/arch/arm/kernel/probes-thumb.h
+++ b/arch/arm/kernel/probes-thumb.h
@@ -87,9 +87,9 @@ extern const union decode_item probes_decode_thumb16_table[];

enum probes_insn __kprobes
thumb16_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *actions);
+ bool emulate, const union decode_item *actions);
enum probes_insn __kprobes
thumb32_probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *actions);
+ bool emulate, const union decode_item *actions);

#endif
diff --git a/arch/arm/kernel/probes.c b/arch/arm/kernel/probes.c
index a0a4220..e691e12 100644
--- a/arch/arm/kernel/probes.c
+++ b/arch/arm/kernel/probes.c
@@ -193,7 +193,7 @@ void __kprobes probes_emulate_none(probes_opcode_t opcode,
*/
static probes_opcode_t __kprobes
prepare_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- bool thumb)
+ bool thumb)
{
#ifdef CONFIG_THUMB2_KERNEL
if (thumb) {
@@ -218,7 +218,7 @@ prepare_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
*/
static void __kprobes
set_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- bool thumb)
+ bool thumb)
{
#ifdef CONFIG_THUMB2_KERNEL
if (thumb) {
@@ -253,7 +253,7 @@ set_emulated_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
* non-zero value, the corresponding nibble in pinsn is validated and modified
* according to the type.
*/
-static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs)
+static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs, bool modify)
{
probes_opcode_t insn = *pinsn;
probes_opcode_t mask = 0xf; /* Start at least significant nibble */
@@ -317,9 +317,16 @@ static bool __kprobes decode_regs(probes_opcode_t *pinsn, u32 regs)
/* Replace value of nibble with new register number... */
insn &= ~mask;
insn |= new_bits & mask;
+ if (modify) {
+ /* Replace value of nibble with new register number */
+ insn &= ~mask;
+ insn |= new_bits & mask;
+ }
}

- *pinsn = insn;
+ if (modify)
+ *pinsn = insn;
+
return true;

reject:
@@ -380,14 +387,15 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
*/
int __kprobes
probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *table, bool thumb,
- const union decode_item *actions)
+ const union decode_item *table, bool thumb,
+ bool emulate, const union decode_item *actions)
{
struct decode_header *h = (struct decode_header *)table;
struct decode_header *next;
bool matched = false;

- insn = prepare_emulated_insn(insn, asi, thumb);
+ if (emulate)
+ insn = prepare_emulated_insn(insn, asi, thumb);

for (;; h = next) {
enum decode_type type = h->type_regs.bits & DECODE_TYPE_MASK;
@@ -402,7 +410,7 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
if (!matched && (insn & h->mask.bits) != h->value.bits)
continue;

- if (!decode_regs(&insn, regs))
+ if (!decode_regs(&insn, regs, emulate))
return INSN_REJECTED;

switch (type) {
@@ -415,7 +423,8 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,

case DECODE_TYPE_CUSTOM: {
struct decode_custom *d = (struct decode_custom *)h;
- return actions[d->decoder.bits].decoder(insn, asi, h);
+ return actions[d->decoder.bits].decoder(insn,
+ asi, h);
}

case DECODE_TYPE_SIMULATE: {
@@ -426,6 +435,11 @@ probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,

case DECODE_TYPE_EMULATE: {
struct decode_emulate *d = (struct decode_emulate *)h;
+
+ if (!emulate)
+ return actions[d->handler.bits].decoder(insn,
+ asi, h);
+
asi->insn_handler = actions[d->handler.bits].handler;
set_emulated_insn(insn, asi, thumb);
return INSN_GOOD;
diff --git a/arch/arm/kernel/probes.h b/arch/arm/kernel/probes.h
index 9591c2c..233ab7b 100644
--- a/arch/arm/kernel/probes.h
+++ b/arch/arm/kernel/probes.h
@@ -389,7 +389,7 @@ probes_insn_handler_t probes_emulate_none;

int __kprobes
probes_decode_insn(probes_opcode_t insn, struct arch_specific_insn *asi,
- const union decode_item *table, bool thumb,
+ const union decode_item *table, bool thumb, bool emulate,
const union decode_item *actions);

#endif
--
1.8.1.2


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