> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> index c944136252c6..9653fb5608f2 100644
> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
[ ... ]
> @@ -388,14 +388,15 @@ static int find_uprobes_trampoline(void *tramp_addr)
> return ret;
> }
>
> -static unsigned char nop5[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
> +static unsigned char nop10[10] = { 0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00,
> 0x00, 0x00, 0x00, 0x00 };
> +static unsigned char lea_rsp[5] = { 0x48, 0x8d, 0x64, 0x24, 0x80 };
>
> -static void *find_nop5(void *fn)
> +static void *find_nop10(void *fn)
> {
> int i;
>
> - for (i = 0; i < 10; i++) {
> - if (!memcmp(nop5, fn + i, 5))
> + for (i = 0; i < 128; i++) {
> + if (!memcmp(nop10, fn + i, 10))
> return fn + i;
> }
> return NULL;
[ ... ]
> @@ -432,7 +434,7 @@ static void check_detach(void *addr, void *tramp)
> {
> /* [uprobes_trampoline] stays after detach */
> ASSERT_OK(find_uprobes_trampoline(tramp), "uprobes_trampoline");
> - ASSERT_OK(memcmp(addr, nop5, 5), "nop5");
> + ASSERT_OK(memcmp(addr, jmp2B, 2), "jmp2B");
> }
Is jmp2B declared somewhere? The identifier is used in memcmp() but does
not appear to be defined anywhere in the file or included headers. A
subsequent commit later in the series replaces this with a properly
declared nop10_prefix array, confirming this is likely a missing
definition.
The pre-patch code referenced the defined static array nop5, but the new
code references an undeclared symbol that will cause a compilation error.
> diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c
> b/tools/testing/selftests/bpf/prog_tests/usdt.c
> index 69759b27794d..fda3a298ccfc 100644
> --- a/tools/testing/selftests/bpf/prog_tests/usdt.c
> +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c
> @@ -252,7 +252,7 @@ extern void usdt_1(void);
> extern void usdt_2(void);
>
> static unsigned char nop1[1] = { 0x90 };
> -static unsigned char nop1_nop5_combo[6] = { 0x90, 0x0f, 0x1f, 0x44, 0x00,
> 0x00 };
> +static unsigned char nop1_nop10_combo[11] = { 0x90, 0x66, 0x2e, 0x0f, 0x1f,
> 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 };
>
> static void *find_instr(void *fn, unsigned char *instr, size_t cnt)
> {
> int i;
>
> for (i = 0; i < 10; i++) {
> if (!memcmp(instr, fn + i, cnt))
> return fn + i;
> }
> return NULL;
> }
Is the loop in find_instr() adequate to find this instruction sequence?
In uprobe_syscall.c, find_nop10() was updated to search up to 128 bytes
to account for compiler-generated prologues:
tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c:find_nop10() {
for (i = 0; i < 128; i++) {
if (!memcmp(nop10, fn + i, 10))
return fn + i;
}
}
If a modern compiler generates a prologue longer than 9 bytes for
usdt_2(), find_instr() will prematurely terminate and cause the
subtest_optimized_attach() test to fail. This was acknowledged in v2
review with "yea find_instr needs same update, will fix" but remains
unchanged.
[ ... ]
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/26227520868
