From 46c7405df7de8deb97229eacebcee96d61415f3f Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 12 May 2021 19:42:10 +0200 Subject: [PATCH 1/2] objtool: Fix elf_create_undef_symbol() endianness Currently x86 cross-compilation fails on big endian system with: x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab' Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf does endianness handling correctly. Fixes: 2f2f7e47f052 ("objtool: Add elf_create_undef_symbol()") Signed-off-by: Vasily Gorbik Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours --- tools/objtool/elf.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index d08f5f3670f8..743c2e9d0f56 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -762,6 +762,7 @@ struct symbol *elf_create_undef_symbol(struct elf *elf, const char *name) data->d_buf = &sym->sym; data->d_size = sizeof(sym->sym); data->d_align = 1; + data->d_type = ELF_T_SYM; sym->idx = symtab->len / sizeof(sym->sym); From f66c05d6baf36069c01a02f869bebb75586f2318 Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 12 May 2021 19:42:13 +0200 Subject: [PATCH 2/2] 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 Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours --- tools/objtool/arch/x86/decode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index cedf3ede7545..24295d39713b 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -19,6 +19,7 @@ #include #include #include +#include #include 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;