[PATCH -v5 07/17] x86/alternative: Add text_opcode_size()

Peter Zijlstra
2019-11-11T14:47:51Z

Introduce a common helper to map *_INSN_OPCODE to *_INSN_SIZE.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/text-patching.h | 43 +++++++++++++++++++++++++----------
arch/x86/kernel/alternative.c | 12 ---------
2 files changed, 32 insertions(+), 23 deletions(-)

--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -49,18 +49,6 @@ extern void text_poke_bp(void *addr, con
extern void text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate);
extern void text_poke_finish(void);

-extern void *text_gen_insn(u8 opcode, const void *addr, const void *dest);
-
-extern int after_bootmem;
-extern __ro_after_init struct mm_struct *poking_mm;
-extern __ro_after_init unsigned long poking_addr;
-
-#ifndef CONFIG_UML_X86
-static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
-{
- regs->ip = ip;
-}
-
#define INT3_INSN_SIZE 1
#define INT3_INSN_OPCODE 0xCC

@@ -73,6 +61,37 @@ static inline void int3_emulate_jmp(stru
#define JMP8_INSN_SIZE 2
#define JMP8_INSN_OPCODE 0xEB

+static inline int text_opcode_size(u8 opcode)
+{
+ int size = 0;
+
+#define __CASE(insn) \
+ case insn##_INSN_OPCODE: size = insn##_INSN_SIZE; break
+
+ switch(opcode) {
+ __CASE(INT3);
+ __CASE(CALL);
+ __CASE(JMP32);
+ __CASE(JMP8);
+ }
+
+#undef __CASE
+
+ return size;
+}
+
+extern void *text_gen_insn(u8 opcode, const void *addr, const void *dest);
+
+extern int after_bootmem;
+extern __ro_after_init struct mm_struct *poking_mm;
+extern __ro_after_init unsigned long poking_addr;
+
+#ifndef CONFIG_UML_X86
+static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+{
+ regs->ip = ip;
+}
+
static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
{
/*
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1259,22 +1259,12 @@ union text_poke_insn {
void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
{
static union text_poke_insn insn; /* text_mutex */
- int size = 0;
+ int size = text_opcode_size(opcode);

lockdep_assert_held(&text_mutex);

insn.opcode = opcode;

-#define __CASE(insn) \
- case insn##_INSN_OPCODE: size = insn##_INSN_SIZE; break
-
- switch(opcode) {
- __CASE(INT3);
- __CASE(CALL);
- __CASE(JMP32);
- __CASE(JMP8);
- }
-
if (size > 1) {
insn.disp = (long)dest - (long)(addr + size);
if (size == 2)