[PATCH 1/2] bpf: align function entry point to 64 bits

YiFei Zhu zhuyifei1999@gmail.com
Thu Apr 22 10:05:56 GMT 2021


Libbpf does not treat paddings after functions well. If function
symbols does not cover a whole text section, it will emit error
similar to:

  libbpf: sec '.text': failed to find program symbol at offset 56

Each instruction in BPF is a multiple of 8 bytes, so align the
functions to 8 bytes, similar to how clang does it.

2021-04-22  YiFei Zhu  <zhuyifei1999@gmail.com>

gcc/

	* config/bpf/bpf.h (FUNCTION_BOUNDARY): Set to 64.
---
 gcc/config/bpf/bpf.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/config/bpf/bpf.h b/gcc/config/bpf/bpf.h
index ef0123b56a63..7ff2f310d583 100644
--- a/gcc/config/bpf/bpf.h
+++ b/gcc/config/bpf/bpf.h
@@ -57,8 +57,8 @@
    64-bit at any time.  */
 #define STACK_BOUNDARY 64
 
-/* Function entry points are aligned to 128 bits.  */
-#define FUNCTION_BOUNDARY 128
+/* Function entry points are aligned to 64 bits.  */
+#define FUNCTION_BOUNDARY 64
 
 /* Maximum alignment required by data of any type.  */
 #define BIGGEST_ALIGNMENT 64
-- 
2.31.1



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