On 12/20/13 09:58, Jon Medhurst (Tixy) wrote:
On Sun, 2013-12-15 at 23:08 -0500, David Long wrote:
From: "David A. Long" <[email protected]>
Add an emulate flag into the instruction interpreter, primarily for uprobes
support.
Signed-off-by: David A. Long <[email protected]>
---
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)) {
Any reason why the function args need splitting over two lines?
I undid the that change.
case INSN_REJECTED: /* not supported */
return -EINVAL;
[...]
--- 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)
Seems like a spurious indentation change.
Fixed.
{
#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)
Another spurious whitespace change.
Fixed.
{
#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;
+ }
Huh? As is, the above addition doesn't do anything because insn has
already been modified. I guess you played with the idea that you needed
to avoid changing insn (you don't) and then didn't undo the experiment
quite right. :-)
The conditional modification of the instruction was part of Rabin's
original work for uprobes, but I messed up the merge from an earlier
working version of my patches. My intention was/is to delete the old
unconditional code. Sounds like maybe you disagree though. The intent
is to only modify the instruction in the kprobes case.
}
- *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);
No need to split the above line, you haven't changed it and it doesn't
exceed 80 characters anyway.
Fixed.
[Rest of patch cut]
-dl
--
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