[PATCH 5.13 348/800] objtool: Dont make .altinstructions writable

[Greg Kroah-Hartman]

From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

[ Upstream commit e31694e0a7a709293319475d8001e05e31f2178c ]

When objtool creates the .altinstructions section, it sets the SHF_WRITE
flag to make the section writable -- unless the section had already been
previously created by the kernel.  The mismatch between kernel-created
and objtool-created section flags can cause failures with external
tooling (kpatch-build).  And the section doesn't need to be writable
anyway.

Make the section flags consistent with the kernel's.

Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Reported-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/6c284ae89717889ea136f9f0064d914cd8329d31.1624462939.git.jpoimboe@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 tools/objtool/arch/x86/decode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 523aa4157f80..bc821056aba9 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -684,7 +684,7 @@ static int elf_add_alternative(struct elf *elf,
 	sec = find_section_by_name(elf, ".altinstructions");
 	if (!sec) {
 		sec = elf_create_section(elf, ".altinstructions",
-					 SHF_WRITE, size, 0);
+					 SHF_ALLOC, size, 0);
 
 		if (!sec) {
 			WARN_ELF("elf_create_section");
-- 
2.30.2