Using 5-byte nop for x86 usdt probes so we can switch
to optimized uprobe them.

Signed-off-by: Jiri Olsa <jo...@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 ca0162b4dc57..7ac9291f45f1 100644
--- a/tools/testing/selftests/bpf/sdt.h
+++ b/tools/testing/selftests/bpf/sdt.h
@@ -234,6 +234,13 @@ __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
 
@@ -286,7 +293,7 @@ __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)          \
-- 
2.47.0


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