2021-05-12 19:45:55

by Vasily Gorbik

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Subject: [PATCH 0/2] objtool: fixes for couple of endianness issues which appeared in v5.13-rc1

Vasily Gorbik (2):
objtool: Fix elf_create_undef_symbol() endianness
objtool/x86: Fix elf_add_alternative() endianness

tools/objtool/arch/x86/decode.c | 3 ++-
tools/objtool/elf.c | 1 +
2 files changed, 3 insertions(+), 1 deletion(-)

--
2.25.4


2021-05-12 19:58:05

by Vasily Gorbik

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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 <[email protected]>
---
tools/objtool/elf.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index a8a0ee21f71a..4d0d4d7a9aba 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -791,6 +791,7 @@ 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);

--
2.25.4

2021-05-12 20:00:00

by Vasily Gorbik

[permalink] [raw]
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 <[email protected]>
---
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 <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;

--
2.25.4