[PATCH RFCv3 12/23] selftests/bpf: Use 5-byte nop for x86 usdt probes
From: Jiri Olsa <jolsa@kernel.org>
Date: 2025-03-20 11:44:21
Also in:
bpf, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Linus Torvalds
Using 5-byte nop for x86 usdt probes so we can switch to optimized uprobe them. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- tools/testing/selftests/bpf/sdt.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/sdt.h b/tools/testing/selftests/bpf/sdt.h
index 1fcfa5160231..1d62c06f5ddc 100644
--- a/tools/testing/selftests/bpf/sdt.h
+++ b/tools/testing/selftests/bpf/sdt.h@@ -236,6 +236,13 @@ __extension__ extern unsigned long long __sdt_unsp; #define _SDT_NOP nop #endif +/* Use 5 byte nop for x86_64 to allow optimizing uprobes. */ +#if defined(__x86_64__) +# define _SDT_DEF_NOP _SDT_ASM_5(990: .byte 0x0f, 0x1f, 0x44, 0x00, 0x00) +#else +# define _SDT_DEF_NOP _SDT_ASM_1(990: _SDT_NOP) +#endif + #define _SDT_NOTE_NAME "stapsdt" #define _SDT_NOTE_TYPE 3
@@ -288,7 +295,7 @@ __extension__ extern unsigned long long __sdt_unsp; #define _SDT_ASM_BODY(provider, name, pack_args, args, ...) \ _SDT_DEF_MACROS \ - _SDT_ASM_1(990: _SDT_NOP) \ + _SDT_DEF_NOP \ _SDT_ASM_3( .pushsection .note.stapsdt,_SDT_ASM_AUTOGROUP,"note") \ _SDT_ASM_1( .balign 4) \ _SDT_ASM_3( .4byte 992f-991f, 994f-993f, _SDT_NOTE_TYPE) \
--
2.49.0