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Message-ID: <175611748217.1420.2474971071317273816.tip-bot2@tip-bot2>
Date: Mon, 25 Aug 2025 10:24:42 -0000
From: "tip-bot2 for Jiri Olsa" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Jiri Olsa <jolsa@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Andrii Nakryiko <andrii@...nel.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: perf/core] selftests/bpf: Add uprobe_regs_equal test
The following commit has been merged into the perf/core branch of tip:
Commit-ID: 275eae6789864904a7319fbb4e993734a0fb4310
Gitweb: https://git.kernel.org/tip/275eae6789864904a7319fbb4e993734a0fb4310
Author: Jiri Olsa <jolsa@...nel.org>
AuthorDate: Sun, 20 Jul 2025 13:21:28 +02:00
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 21 Aug 2025 20:09:25 +02:00
selftests/bpf: Add uprobe_regs_equal test
Changing uretprobe_regs_trigger to allow the test for both
uprobe and uretprobe and renaming it to uprobe_regs_equal.
We check that both uprobe and uretprobe probes (bpf programs)
see expected registers with few exceptions.
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Andrii Nakryiko <andrii@...nel.org>
Link: https://lore.kernel.org/r/20250720112133.244369-19-jolsa@kernel.org
---
tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c | 56 ++++++--
tools/testing/selftests/bpf/progs/uprobe_syscall.c | 4 +-
2 files changed, 44 insertions(+), 16 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
index 02e98cb..36ce9e2 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
@@ -22,15 +22,17 @@
#pragma GCC diagnostic ignored "-Wattributes"
-__naked unsigned long uretprobe_regs_trigger(void)
+__attribute__((aligned(16)))
+__nocf_check __weak __naked unsigned long uprobe_regs_trigger(void)
{
asm volatile (
+ ".byte 0x0f, 0x1f, 0x44, 0x00, 0x00\n" /* nop5 */
"movq $0xdeadbeef, %rax\n"
"ret\n"
);
}
-__naked void uretprobe_regs(struct pt_regs *before, struct pt_regs *after)
+__naked void uprobe_regs(struct pt_regs *before, struct pt_regs *after)
{
asm volatile (
"movq %r15, 0(%rdi)\n"
@@ -51,15 +53,17 @@ __naked void uretprobe_regs(struct pt_regs *before, struct pt_regs *after)
"movq $0, 120(%rdi)\n" /* orig_rax */
"movq $0, 128(%rdi)\n" /* rip */
"movq $0, 136(%rdi)\n" /* cs */
+ "pushq %rax\n"
"pushf\n"
"pop %rax\n"
"movq %rax, 144(%rdi)\n" /* eflags */
+ "pop %rax\n"
"movq %rsp, 152(%rdi)\n" /* rsp */
"movq $0, 160(%rdi)\n" /* ss */
/* save 2nd argument */
"pushq %rsi\n"
- "call uretprobe_regs_trigger\n"
+ "call uprobe_regs_trigger\n"
/* save return value and load 2nd argument pointer to rax */
"pushq %rax\n"
@@ -99,25 +103,37 @@ __naked void uretprobe_regs(struct pt_regs *before, struct pt_regs *after)
);
}
-static void test_uretprobe_regs_equal(void)
+static void test_uprobe_regs_equal(bool retprobe)
{
+ LIBBPF_OPTS(bpf_uprobe_opts, opts,
+ .retprobe = retprobe,
+ );
struct uprobe_syscall *skel = NULL;
struct pt_regs before = {}, after = {};
unsigned long *pb = (unsigned long *) &before;
unsigned long *pa = (unsigned long *) &after;
unsigned long *pp;
+ unsigned long offset;
unsigned int i, cnt;
- int err;
+
+ offset = get_uprobe_offset(&uprobe_regs_trigger);
+ if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+ return;
skel = uprobe_syscall__open_and_load();
if (!ASSERT_OK_PTR(skel, "uprobe_syscall__open_and_load"))
goto cleanup;
- err = uprobe_syscall__attach(skel);
- if (!ASSERT_OK(err, "uprobe_syscall__attach"))
+ skel->links.probe = bpf_program__attach_uprobe_opts(skel->progs.probe,
+ 0, "/proc/self/exe", offset, &opts);
+ if (!ASSERT_OK_PTR(skel->links.probe, "bpf_program__attach_uprobe_opts"))
goto cleanup;
- uretprobe_regs(&before, &after);
+ /* make sure uprobe gets optimized */
+ if (!retprobe)
+ uprobe_regs_trigger();
+
+ uprobe_regs(&before, &after);
pp = (unsigned long *) &skel->bss->regs;
cnt = sizeof(before)/sizeof(*pb);
@@ -126,7 +142,7 @@ static void test_uretprobe_regs_equal(void)
unsigned int offset = i * sizeof(unsigned long);
/*
- * Check register before and after uretprobe_regs_trigger call
+ * Check register before and after uprobe_regs_trigger call
* that triggers the uretprobe.
*/
switch (offset) {
@@ -140,7 +156,7 @@ static void test_uretprobe_regs_equal(void)
/*
* Check register seen from bpf program and register after
- * uretprobe_regs_trigger call
+ * uprobe_regs_trigger call (with rax exception, check below).
*/
switch (offset) {
/*
@@ -153,6 +169,15 @@ static void test_uretprobe_regs_equal(void)
case offsetof(struct pt_regs, rsp):
case offsetof(struct pt_regs, ss):
break;
+ /*
+ * uprobe does not see return value in rax, it needs to see the
+ * original (before) rax value
+ */
+ case offsetof(struct pt_regs, rax):
+ if (!retprobe) {
+ ASSERT_EQ(pp[i], pb[i], "uprobe rax prog-before value check");
+ break;
+ }
default:
if (!ASSERT_EQ(pp[i], pa[i], "register prog-after value check"))
fprintf(stdout, "failed register offset %u\n", offset);
@@ -190,13 +215,13 @@ static void test_uretprobe_regs_change(void)
unsigned long cnt = sizeof(before)/sizeof(*pb);
unsigned int i, err, offset;
- offset = get_uprobe_offset(uretprobe_regs_trigger);
+ offset = get_uprobe_offset(uprobe_regs_trigger);
err = write_bpf_testmod_uprobe(offset);
if (!ASSERT_OK(err, "register_uprobe"))
return;
- uretprobe_regs(&before, &after);
+ uprobe_regs(&before, &after);
err = write_bpf_testmod_uprobe(0);
if (!ASSERT_OK(err, "unregister_uprobe"))
@@ -616,7 +641,8 @@ static void test_uretprobe_shadow_stack(void)
/* Run all the tests with shadow stack in place. */
shstk_is_enabled = true;
- test_uretprobe_regs_equal();
+ test_uprobe_regs_equal(false);
+ test_uprobe_regs_equal(true);
test_uretprobe_regs_change();
test_uretprobe_syscall_call();
@@ -772,7 +798,7 @@ static void test_uprobe_sigill(void)
static void __test_uprobe_syscall(void)
{
if (test__start_subtest("uretprobe_regs_equal"))
- test_uretprobe_regs_equal();
+ test_uprobe_regs_equal(true);
if (test__start_subtest("uretprobe_regs_change"))
test_uretprobe_regs_change();
if (test__start_subtest("uretprobe_syscall_call"))
@@ -791,6 +817,8 @@ static void __test_uprobe_syscall(void)
test_uprobe_race();
if (test__start_subtest("uprobe_sigill"))
test_uprobe_sigill();
+ if (test__start_subtest("uprobe_regs_equal"))
+ test_uprobe_regs_equal(false);
}
#else
static void __test_uprobe_syscall(void)
diff --git a/tools/testing/selftests/bpf/progs/uprobe_syscall.c b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
index 8a4fa6c..e08c316 100644
--- a/tools/testing/selftests/bpf/progs/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
@@ -7,8 +7,8 @@ struct pt_regs regs;
char _license[] SEC("license") = "GPL";
-SEC("uretprobe//proc/self/exe:uretprobe_regs_trigger")
-int uretprobe(struct pt_regs *ctx)
+SEC("uprobe")
+int probe(struct pt_regs *ctx)
{
__builtin_memcpy(®s, ctx, sizeof(regs));
return 0;
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