objtool/x86: Fix elf_add_alternative() endianness

Currently x86 kernel cross-compiled on big endian system fails at boot with:

  kernel BUG at arch/x86/kernel/alternative.c:258!

Corresponding bug condition look like the following:

  BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);

Fix that by converting alternative feature/cpuid to target endianness.

Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index cedf3ed..24295d3 100644 (file)
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -19,6 +19,7 @@
 #include <objtool/elf.h>
 #include <objtool/arch.h>
 #include <objtool/warn.h>
+#include <objtool/endianness.h>
 #include <arch/elf.h>
 
 static int is_x86_64(const struct elf *elf)
@@ -725,7 +726,7 @@ static int elf_add_alternative(struct elf *elf,
                return -1;
        }
 
-       alt->cpuid = cpuid;
+       alt->cpuid = bswap_if_needed(cpuid);
        alt->instrlen = orig_len;
        alt->replacementlen = repl_len;