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Message-ID: <20250801210238.2207429-4-jolsa@kernel.org>
Date: Fri, 1 Aug 2025 23:02:37 +0200
From: Jiri Olsa <jolsa@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Andrii Nakryiko <andrii@...nel.org>
Cc: bpf@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org,
x86@...nel.org,
Song Liu <songliubraving@...com>,
Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
Hao Luo <haoluo@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>
Subject: [RFC 3/4] selftests/bpf: Add uprobe context registers changes test
Adding test to check we can change common register values through
uprobe program.
It's x86_64 specific test.
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
.../testing/selftests/bpf/prog_tests/uprobe.c | 114 +++++++++++++++++-
.../testing/selftests/bpf/progs/test_uprobe.c | 24 ++++
2 files changed, 137 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe.c b/tools/testing/selftests/bpf/prog_tests/uprobe.c
index cf3e0e7a64fa..7c7cb08d10b3 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe.c
@@ -2,6 +2,7 @@
/* Copyright (c) 2023 Hengqi Chen */
#include <test_progs.h>
+#include <asm/ptrace.h>
#include "test_uprobe.skel.h"
static FILE *urand_spawn(int *pid)
@@ -33,7 +34,7 @@ static int urand_trigger(FILE **urand_pipe)
return exit_code;
}
-void test_uprobe(void)
+static void test_uprobe_attach(void)
{
LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
struct test_uprobe *skel;
@@ -93,3 +94,114 @@ void test_uprobe(void)
pclose(urand_pipe);
test_uprobe__destroy(skel);
}
+
+#ifdef __x86_64__
+__naked __maybe_unused unsigned long uprobe_regs_change_trigger(void)
+{
+ asm volatile (
+ "ret\n"
+ );
+}
+
+static __naked void uprobe_regs_change(struct pt_regs *before, struct pt_regs *after)
+{
+ asm volatile (
+ "movq %r11, 48(%rdi)\n"
+ "movq %r10, 56(%rdi)\n"
+ "movq %r9, 64(%rdi)\n"
+ "movq %r8, 72(%rdi)\n"
+ "movq %rax, 80(%rdi)\n"
+ "movq %rcx, 88(%rdi)\n"
+ "movq %rdx, 96(%rdi)\n"
+ "movq %rsi, 104(%rdi)\n"
+ "movq %rdi, 112(%rdi)\n"
+
+ /* save 2nd argument */
+ "pushq %rsi\n"
+ "call uprobe_regs_change_trigger\n"
+
+ /* save return value and load 2nd argument pointer to rax */
+ "pushq %rax\n"
+ "movq 8(%rsp), %rax\n"
+
+ "movq %r11, 48(%rax)\n"
+ "movq %r10, 56(%rax)\n"
+ "movq %r9, 64(%rax)\n"
+ "movq %r8, 72(%rax)\n"
+ "movq %rcx, 88(%rax)\n"
+ "movq %rdx, 96(%rax)\n"
+ "movq %rsi, 104(%rax)\n"
+ "movq %rdi, 112(%rax)\n"
+
+ /* restore return value and 2nd argument */
+ "pop %rax\n"
+ "pop %rsi\n"
+
+ "movq %rax, 80(%rsi)\n"
+ "ret\n"
+ );
+}
+
+static void regs_common(void)
+{
+ struct pt_regs before = {}, after = {}, expected = {
+ .rax = 0xc0ffe,
+ .rcx = 0xbad,
+ .rdx = 0xdead,
+ .r8 = 0x8,
+ .r9 = 0x9,
+ .r10 = 0x10,
+ .r11 = 0x11,
+ .rdi = 0x12,
+ .rsi = 0x13,
+ };
+ LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
+ struct test_uprobe *skel;
+
+ skel = test_uprobe__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open"))
+ return;
+
+ skel->bss->my_pid = getpid();
+ skel->bss->regs = expected;
+
+ uprobe_opts.func_name = "uprobe_regs_change_trigger";
+ skel->links.test_regs_change = bpf_program__attach_uprobe_opts(skel->progs.test_regs_change,
+ -1,
+ "/proc/self/exe",
+ 0 /* offset */,
+ &uprobe_opts);
+ if (!ASSERT_OK_PTR(skel->links.test_regs_change, "bpf_program__attach_uprobe_opts"))
+ goto cleanup;
+
+ uprobe_regs_change(&before, &after);
+
+ ASSERT_EQ(after.rax, expected.rax, "ax");
+ ASSERT_EQ(after.rcx, expected.rcx, "cx");
+ ASSERT_EQ(after.rdx, expected.rdx, "dx");
+ ASSERT_EQ(after.r8, expected.r8, "r8");
+ ASSERT_EQ(after.r9, expected.r9, "r9");
+ ASSERT_EQ(after.r10, expected.r10, "r10");
+ ASSERT_EQ(after.r11, expected.r11, "r11");
+ ASSERT_EQ(after.rdi, expected.rdi, "rdi");
+ ASSERT_EQ(after.rsi, expected.rsi, "rsi");
+
+cleanup:
+ test_uprobe__destroy(skel);
+}
+
+static void test_uprobe_regs_change(void)
+{
+ if (test__start_subtest("regs_change_common"))
+ regs_common();
+}
+#else
+static void test_uprobe_regs_change(void) { }
+#endif
+
+void test_uprobe(void)
+{
+ if (test__start_subtest("attach"))
+ test_uprobe_attach();
+ test_uprobe_regs_change();
+}
diff --git a/tools/testing/selftests/bpf/progs/test_uprobe.c b/tools/testing/selftests/bpf/progs/test_uprobe.c
index 896c88a4960d..9437bd76a437 100644
--- a/tools/testing/selftests/bpf/progs/test_uprobe.c
+++ b/tools/testing/selftests/bpf/progs/test_uprobe.c
@@ -59,3 +59,27 @@ int BPF_UPROBE(test4)
test4_result = 1;
return 0;
}
+
+#if defined(__TARGET_ARCH_x86)
+struct pt_regs regs;
+
+SEC("uprobe")
+int BPF_UPROBE(test_regs_change)
+{
+ pid_t pid = bpf_get_current_pid_tgid() >> 32;
+
+ if (pid != my_pid)
+ return 0;
+
+ ctx->ax = regs.ax;
+ ctx->cx = regs.cx;
+ ctx->dx = regs.dx;
+ ctx->r8 = regs.r8;
+ ctx->r9 = regs.r9;
+ ctx->r10 = regs.r10;
+ ctx->r11 = regs.r11;
+ ctx->di = regs.di;
+ ctx->si = regs.si;
+ return 0;
+}
+#endif
--
2.50.1
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