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authorPeter Zijlstra <peterz@infradead.org>2019-10-03 14:50:42 +0200
committerIngo Molnar <mingo@kernel.org>2019-11-27 07:44:24 +0100
commit63f62addb88ec4b358cf4574789bc3180c689e9a (patch)
tree251af1ec2b3fc9ebfaee7fe2a89cb9201dd18750 /arch/x86/kernel/alternative.c
parentx86/alternatives, jump_label: Provide better text_poke() batching interface (diff)
downloadlinux-63f62addb88ec4b358cf4574789bc3180c689e9a.tar.xz
linux-63f62addb88ec4b358cf4574789bc3180c689e9a.zip
x86/alternatives: Add and use text_gen_insn() helper
Provide a simple helper function to create common instruction encodings. 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: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20191111132457.703538332@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/alternative.c')
-rw-r--r--arch/x86/kernel/alternative.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 42e7f0af88da..714b4a2a6f81 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1237,3 +1237,39 @@ void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulat
text_poke_loc_init(&tp, addr, opcode, len, emulate);
text_poke_bp_batch(&tp, 1);
}
+
+union text_poke_insn {
+ u8 text[POKE_MAX_OPCODE_SIZE];
+ struct {
+ u8 opcode;
+ s32 disp;
+ } __attribute__((packed));
+};
+
+void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+{
+ static union text_poke_insn insn; /* text_mutex */
+ int size = 0;
+
+ 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)
+ BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
+ }
+
+ return &insn.text;
+}