On 09/02/2021 12:17, Leo Yan wrote:
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...@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,
Doesn't the width field specify the min, not max, number of characters?
Cheers,
John
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
.
