[PATCH v5] perf tools: Fix arm64 build error with gcc-11

[John Garry]

On 18/02/2021 03:12, Jianlin Lv wrote:
> gcc version: 11.0.0 20210208 (experimental) (GCC)
> 
> Following build error on arm64:
> 
> .......
> In function ‘printf’,
>      inlined from ‘regs_dump__printf’ at util/session.c:1141:3,
>      inlined from ‘regs__printf’ at util/session.c:1169:2:
> /usr/include/aarch64-linux-gnu/bits/stdio2.h:107:10: \
>    error: ‘%-5s’ directive argument is null [-Werror=format-overflow=]
> 
> 107 |   return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, \
>                  __va_arg_pack ());
> 
> ......
> In function ‘fprintf’,
>    inlined from ‘perf_sample__fprintf_regs.isra’ at \
>      builtin-script.c:622:14:
> /usr/include/aarch64-linux-gnu/bits/stdio2.h:100:10: \
>      error: ‘%5s’ directive argument is null [-Werror=format-overflow=]
>    100 |   return __fprintf_chk (__stream, __USE_FORTIFY_LEVEL - 1, __fmt,
>    101 |                         __va_arg_pack ());
> 
> cc1: all warnings being treated as errors
> .......
> 
> This patch fixes Wformat-overflow warnings. Add helper function to
> convert NULL to "unknown".
> 
> Signed-off-by: Jianlin Lv<Jianlin.Lv at arm.com>

thanks
Reviewed-by: John Garry <john.garry at huawei.com>