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Subject[tip: x86/core] x86/text-patching: Make text_gen_insn() play nice with ANNOTATE_NOENDBR
The following commit has been merged into the x86/core branch of tip:

Commit-ID: dbf45ea73312b99208809c3b7a4831d6bb4e6ed8
Gitweb: https://git.kernel.org/tip/dbf45ea73312b99208809c3b7a4831d6bb4e6ed8
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Tue, 08 Mar 2022 16:30:19 +01:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 08 Mar 2022 23:53:28 +01:00

x86/text-patching: Make text_gen_insn() play nice with ANNOTATE_NOENDBR

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.638561109@infradead.org
---
arch/x86/include/asm/text-patching.h | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index b742178..1c4cfb1 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -101,13 +101,21 @@ void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
static union text_poke_insn insn; /* per instance */
int size = text_opcode_size(opcode);

+ /*
+ * Hide the addresses to avoid the compiler folding in constants when
+ * referencing code, these can mess up annotations like
+ * ANNOTATE_NOENDBR.
+ */
+ OPTIMIZER_HIDE_VAR(addr);
+ OPTIMIZER_HIDE_VAR(dest);
+
insn.opcode = opcode;

if (size > 1) {
insn.disp = (long)dest - (long)(addr + size);
if (size == 2) {
/*
- * Ensure that for JMP9 the displacement
+ * Ensure that for JMP8 the displacement
* actually fits the signed byte.
*/
BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
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