[tip: core/kprobes] x86/alternative: Add text_opcode_size()

tip-bot2 for Peter Zijlstra
2019-12-04T08:33:56Z

The following commit has been merged into the core/kprobes branch of tip:

Commit-ID: 254d2c04515ea4532a503cc5d8649e1513042e56
Gitweb: https://git.kernel.org/tip/254d2c04515ea4532a503cc5d8649e1513042e56
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 09 Oct 2019 12:44:17 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 27 Nov 2019 07:44:24 +01:00

x86/alternative: Add text_opcode_size()

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

Tested-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191111132457.875666061@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/text-patching.h | 43 +++++++++++++++++++--------
arch/x86/kernel/alternative.c | 12 +--------
2 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 95beb85..93e4266 100644
--- 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, const void *opcode, size_t len, const void
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(struct pt_regs *regs, unsigned long ip)
#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)
{
/*
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index ce737f1..f8f34f9 100644
--- 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)