[tip: perf/core] libbpf: Change has_nop_combo to work on top of nop10

[tip-bot2 for Jiri Olsa]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     ee2862439e5c8763cee84e910706fdc5b97bc879
Gitweb:        https://git.kernel.org/tip/ee2862439e5c8763cee84e910706fdc5b97bc879
Author:        Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate:    Fri, 03 Jul 2026 13:49:10 +02:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sat, 04 Jul 2026 10:54:59 +02:00

libbpf: Change has_nop_combo to work on top of nop10

We now expect nop combo with 10 bytes nop instead of 5 bytes nop,
fixing has_nop_combo to reflect that.

Fixes: 41a5c7df4466 ("libbpf: Add support to detect nop,nop5 instructions combo for usdt probe")
Fixes: 554ba38456da ("uprobes/x86: Move optimized uprobe from nop5 to nop10")
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://patch.msgid.link/20260703114917.238144-7-jolsa@xxxxxxxxxx
---
 tools/lib/bpf/usdt.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index 57fb82b..d2ecd3d 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -305,7 +305,7 @@ struct usdt_manager *usdt_manager_new(struct bpf_object *obj)
 
 	/*
 	 * Detect kernel support for uprobe() syscall, it's presence means we can
-	 * take advantage of faster nop5 uprobe handling.
+	 * take advantage of faster nop10 uprobe handling.
 	 * Added in: 56101b69c919 ("uprobes/x86: Add uprobe syscall to speed up uprobe")
 	 */
 	man->has_uprobe_syscall = kernel_supports(obj, FEAT_UPROBE_SYSCALL);
@@ -604,14 +604,14 @@ static int parse_usdt_spec(struct usdt_spec *spec, const struct usdt_note *note,
 #if defined(__x86_64__)
 static bool has_nop_combo(int fd, long off)
 {
-	unsigned char nop_combo[6] = {
-		0x90, 0x0f, 0x1f, 0x44, 0x00, 0x00 /* nop,nop5 */
+	unsigned char nop_combo[11] = {
+		0x90, 0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00,
 	};
-	unsigned char buf[6];
+	unsigned char buf[11];
 
-	if (pread(fd, buf, 6, off) != 6)
+	if (pread(fd, buf, 11, off) != 11)
 		return false;
-	return memcmp(buf, nop_combo, 6) == 0;
+	return memcmp(buf, nop_combo, 11) == 0;
 }
 #else
 static bool has_nop_combo(int fd, long off)
@@ -822,8 +822,8 @@ static int collect_usdt_targets(struct usdt_manager *man, struct elf_fd *elf_fd,
 		memset(target, 0, sizeof(*target));
 
 		/*
-		 * We have uprobe syscall and usdt with nop,nop5 instructions combo,
-		 * so we can place the uprobe directly on nop5 (+1) and get this probe
+		 * We have uprobe syscall and usdt with nop,nop10 instructions combo,
+		 * so we can place the uprobe directly on nop10 (+1) and get this probe
 		 * optimized.
 		 */
 		if (man->has_uprobe_syscall && has_nop_combo(elf_fd->fd, usdt_rel_ip)) {