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SubjectRe: [PATCH v4 1/1] x86, relocs: add printf attribute to die()
On Tue, Mar 7, 2017 at 1:37 PM, Nicolas Iooss
<nicolas.iooss_linux@m4x.org> wrote:
> On Tue, Mar 7, 2017 at 10:16 AM, Ingo Molnar <mingo@kernel.org> wrote:
>>
>> * Nicolas Iooss <nicolas.iooss_linux@m4x.org> wrote:
>>
>>> Adding such an attribute helps to detect errors in the format string at
>>> build time. After doing this, the compiler complains about some issues:
>>>
>>> arch/x86/tools/relocs.c:460:5: error: format specifies type 'int'
>>> but the argument has type 'Elf64_Xword' (aka 'unsigned long')
>>> [-Werror,-Wformat]
>>> sec->shdr.sh_size);
>>> ^~~~~~~~~~~~~~~~~
>>> arch/x86/tools/relocs.c:464:5: error: format specifies type 'int'
>>> but the argument has type 'Elf64_Off' (aka 'unsigned long')
>>> [-Werror,-Wformat]
>>> sec->shdr.sh_offset, strerror(errno));
>>> ^~~~~~~~~~~~~~~~~~~
>>>
>>> When relocs.c is included by relocs_32.c, sec->shdr.sh_size and
>>> sec->shdr.sh_offset are 32-bit unsigned integers. When the file is
>>> included by relocs_64.c, these expressions are 64-bit unsigned integers.
>>>
>>> Add casts to unsigned long long, which length is always 64-bit, and use
>>> %llu to format sec->shdr.sh_size and sec->shdr.sh_offset in relocs.c.
>>>
>>> While at it, constify the format attribute of die().
>>>
>>> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
>>> ---
>>> arch/x86/tools/relocs.c | 31 +++++++++++++++++--------------
>>> arch/x86/tools/relocs.h | 3 ++-
>>> arch/x86/tools/relocs_common.c | 2 +-
>>> 3 files changed, 20 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
>>> index 73eb7fd4aec4..3cc02065c677 100644
>>> --- a/arch/x86/tools/relocs.c
>>> +++ b/arch/x86/tools/relocs.c
>>> @@ -397,8 +397,8 @@ static void read_shdrs(FILE *fp)
>>> ehdr.e_shnum);
>>> }
>>> if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
>>> - die("Seek to %d failed: %s\n",
>>> - ehdr.e_shoff, strerror(errno));
>>> + die("Seek to %llu failed: %s\n",
>>> + (unsigned long long)ehdr.e_shoff, strerror(errno));
>>
>> Isn't "(u64)" shorter to write?
>
> u64 does not seem to be defined in this file right now. Adding
> "#include <linux/types.h>" defines u64 and __u64 in the following way:
> - "typedef uint64_t u64;" from tools/include/linux/types.h
> - "typedef unsigned long long __u64;" from /usr/include/asm-generic/int-ll64.h
>
> uint64_t is unsigned long on x86-64 and gcc complains when using %llu
> on such a type, so using a cast to u64 forces using PRIu64 too.
>
> Nevertheless "(__u64)" is shorter than "(unsigned long long)" and
> seems to work fine in my quick tests because it is always unsigned
> long long (on both x86-32 and x86-64). Would you prefer to use this
> cast?

Hello,
After the question I had on the 4th revision of this patch, I have not
received any reply or comment for three weeks. What should I do in
order to get this merged?

Thanks,
Nicolas

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