Intended to handle scenarios where we might want to patch arbitrary
instructions (ex. inlined opcodes in pv_lock_ops.)
Users for native mode (as opposed to emulated) are introduced in
later patches.
Signed-off-by: Ankur Arora
---
arch/x86/include/asm/text-patching.h | 4 +-
arch/x86/kernel/alternative.c| 61
2 files changed, 45 insertions(+), 20 deletions(-)
diff --git a/arch/x86/include/asm/text-patching.h
b/arch/x86/include/asm/text-patching.h
index 04778c2bc34e..c4b2814f2f9d 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -25,10 +25,10 @@ static inline void apply_paravirt(struct
paravirt_patch_site *start,
/*
* Currently, the max observed size in the kernel code is
- * JUMP_LABEL_NOP_SIZE/RELATIVEJUMP_SIZE, which are 5.
+ * NOP7 for indirect call, which is 7.
* Raise it if needed.
*/
-#define POKE_MAX_OPCODE_SIZE 5
+#define POKE_MAX_OPCODE_SIZE 7
extern void text_poke_early(void *addr, const void *opcode, size_t len);
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 337aad8c2521..004fe86f463f 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -981,8 +981,15 @@ void text_poke_sync(void)
struct text_poke_loc {
s32 rel_addr; /* addr := _stext + rel_addr */
- s32 rel32;
- u8 opcode;
+ union {
+ struct {
+ s32 rel32;
+ u8 opcode;
+ } emulated;
+ struct {
+ u8 len;
+ } native;
+ };
const u8 text[POKE_MAX_OPCODE_SIZE];
};
@@ -990,6 +997,7 @@ struct bp_patching_desc {
struct text_poke_loc *vec;
int nr_entries;
atomic_t refs;
+ bool native;
};
static struct bp_patching_desc *bp_desc;
@@ -1071,10 +1079,13 @@ int notrace poke_int3_handler(struct pt_regs *regs)
goto out_put;
}
- len = text_opcode_size(tp->opcode);
+ if (desc->native)
+ BUG();
+
+ len = text_opcode_size(tp->emulated.opcode);
ip += len;
- switch (tp->opcode) {
+ switch (tp->emulated.opcode) {
case INT3_INSN_OPCODE:
/*
* Someone poked an explicit INT3, they'll want to handle it,
@@ -1083,12 +1094,12 @@ int notrace poke_int3_handler(struct pt_regs *regs)
goto out_put;
case CALL_INSN_OPCODE:
- int3_emulate_call(regs, (long)ip + tp->rel32);
+ int3_emulate_call(regs, (long)ip + tp->emulated.rel32);
break;
case JMP32_INSN_OPCODE:
case JMP8_INSN_OPCODE:
- int3_emulate_jmp(regs, (long)ip + tp->rel32);
+ int3_emulate_jmp(regs, (long)ip + tp->emulated.rel32);
break;
default:
@@ -1134,6 +1145,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp,
unsigned int nr_entries
.vec = tp,
.nr_entries = nr_entries,
.refs = ATOMIC_INIT(1),
+ .native = false,
};
unsigned char int3 = INT3_INSN_OPCODE;
unsigned int i;
@@ -1161,7 +1173,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp,
unsigned int nr_entries
* Second step: update all but the first byte of the patched range.
*/
for (do_sync = 0, i = 0; i < nr_entries; i++) {
- int len = text_opcode_size(tp[i].opcode);
+ int len = text_opcode_size(tp[i].emulated.opcode);
if (len - INT3_INSN_SIZE > 0) {
text_poke(text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
@@ -1205,11 +1217,25 @@ static void text_poke_bp_batch(struct text_poke_loc
*tp, unsigned int nr_entries
}
static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
- const void *opcode, size_t len, const void
*emulate)
+ const void *opcode, size_t len,
+ const void *emulate, bool native)
{
struct insn insn;
+ memset((void *)tp, 0, sizeof(*tp));
memcpy((void *)tp->text, opcode, len);
+
+ tp->rel_addr = addr - (void *)_stext;
+
+ /*
+* Native mode: when we might be poking
+* arbitrary (perhaps) multiple instructions.
+*/
+ if (native) {
+ tp->native.len = (u8)len;
+ return;
+ }
+
if (!emulate)
emulate = opcode;
@@ -1219,31 +1245,30 @@ static void text_poke_loc_init(struct text_poke_loc
*tp, void *addr,
BUG_ON(!insn_complete(&insn));
BUG_ON(len != insn.length);
- tp->rel_addr = addr - (void *)_stext;
- tp->opcode = insn.opcode.bytes[0];
+ tp->emulated.opcode = insn.opcode.bytes[0];
- switch (tp->opcode) {
+ switch (tp->emulated.opcode) {
case INT3_INSN_OPCODE:
