libbpf accesses the ELF data requiring at least 8 byte alignment,
however, the data is generated into a C string that doesn't guarantee
alignment. Fix this by assigning to an aligned char array. Use sizeof
on the array, less one for the \0 terminator, rather than generating a
constant.
Fixes: a6cc6b34b93e ("bpftool: Provide a helper method for accessing skeleton's embedded ELF data")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Acked-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
tools/bpf/bpftool/gen.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 04c47745b3ea..882bf8e6e70e 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -1209,7 +1209,7 @@ static int do_skeleton(int argc, char **argv)
codegen("\
\n\
\n\
- s->data = %2$s__elf_bytes(&s->data_sz); \n\
+ s->data = %1$s__elf_bytes(&s->data_sz); \n\
\n\
obj->skeleton = s; \n\
return 0; \n\
@@ -1218,12 +1218,12 @@ static int do_skeleton(int argc, char **argv)
return err; \n\
} \n\
\n\
- static inline const void *%2$s__elf_bytes(size_t *sz) \n\
+ static inline const void *%1$s__elf_bytes(size_t *sz) \n\
{ \n\
- *sz = %1$d; \n\
- return (const void *)\"\\ \n\
- "
- , file_sz, obj_name);
+ static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
+ ",
+ obj_name
+ );
/* embed contents of BPF object file */
print_hex(obj_data, file_sz);
@@ -1231,6 +1231,9 @@ static int do_skeleton(int argc, char **argv)
codegen("\
\n\
\"; \n\
+ \n\
+ *sz = sizeof(data) - 1; \n\
+ return (const void *)data; \n\
} \n\
\n\
#ifdef __cplusplus \n\
--
2.42.0.609.gbb76f46606-goog
