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>

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 95beb85aef65a75e3b3d04915a1ddc31bc54cd1a..93e4266cd5a3d7ba44e515acf2a65a1f8729ff18 100644 (file)
--- 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 ce737f1da834f890170702558ddb4b8d654fbb98..f8f34f94d13d221d0757bef11b55167ed371ed68 100644 (file)
--- 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)