Messages in this thread Patch in this message | | | Date | Tue, 9 Feb 2021 20:17:28 +0800 | From | Leo Yan <> | Subject | Re: [PATCH] perf tools: Fix arm64 build error with gcc-11 |
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Hi Jianlin,
On Tue, Feb 09, 2021 at 07:33:57PM +0800, 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 by replacing the return > value NULL of perf_reg_name with "unknown". > > Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com> > --- > tools/perf/arch/arm64/include/perf_regs.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/arch/arm64/include/perf_regs.h b/tools/perf/arch/arm64/include/perf_regs.h > index baaa5e64a3fb..901419f907c0 100644 > --- a/tools/perf/arch/arm64/include/perf_regs.h > +++ b/tools/perf/arch/arm64/include/perf_regs.h > @@ -85,10 +85,10 @@ static inline const char *perf_reg_name(int id) > case PERF_REG_ARM64_PC: > return "pc"; > default: > - return NULL; > + return "unknown"; > } > > - return NULL; > + return "unknown";
This issue is a common issue crossing all archs. So it's better to change the code in the places where calls perf_reg_name(), e.g. in util/session.c:
--- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1135,12 +1135,14 @@ static void branch_stack__printf(struct perf_sample *sample, bool callstack) static void regs_dump__printf(u64 mask, u64 *regs) { unsigned rid, i = 0; + char *reg_name; for_each_set_bit(rid, (unsigned long *) &mask, sizeof(mask) * 8) { u64 val = regs[i++]; + reg_name = perf_reg_name(rid); printf(".... %-5s 0x%016" PRIx64 "\n", - perf_reg_name(rid), val); + reg_name ?: "Unknown", val); } }
And another potential issue is the format specifier "%-5s", it prints out maximum to 5 chars, but actually string "Unknown" has 7 chars. Actually the format specifier breaks other archs register names, e.g. [1][2], seems to me, it's better to change as "%-8s", you might need to use a dedicated patch for format specifier changes. Thanks, Leo
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/arch/powerpc/include/perf_regs.h#n57 [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/arch/csky/include/perf_regs.h#n83
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