GCC warns that `val' may be used uninitialized in the
BPF_CORE_READ_BITFIELD macro, defined in bpf_core_read.h as:
[...]
unsigned long long val; \
[...] \
switch (__CORE_RELO(s, field, BYTE_SIZE)) { \
case 1: val = *(const unsigned char *)p; break; \
case 2: val = *(const unsigned short *)p; break; \
case 4: val = *(const unsigned int *)p; break; \
case 8: val = *(const unsigned long long *)p; break; \
} \
[...]
val; \
} \
This patch initializes `val' to zero in order to avoid the warning,
and random values to be used in case __builtin_preserve_field_info
returns unexpected values for BPF_FIELD_BYTE_SIZE.
Tested in bpf-next master.
No regressions.
Signed-off-by: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx>
Cc: david.faust@xxxxxxxxxx
Cc: cupertino.miranda@xxxxxxxxxx
Cc: Eduard Zingerman <eddyz87@xxxxxxxxx>
Cc: Yonghong Song <yonghong.song@xxxxxxxxx>
---
tools/lib/bpf/bpf_core_read.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index b5c7ce5c243a..88d129b5f0a1 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -89,7 +89,7 @@ enum bpf_enum_value_kind {
*/
#define BPF_CORE_READ_BITFIELD(s, field) ({ \
const void *p = (const void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \
- unsigned long long val; \
+ unsigned long long val = 0; \
\
/* This is a so-called barrier_var() operation that makes specified \
* variable "a black box" for optimizing compiler. \
--
2.30.2
