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Subject[PATCHv3 bpf-next 3/7] selftests/bpf: Add uretprobe syscall test for regs integrity
Date
Add uretprobe syscall test that compares register values before
and after the uretprobe is hit. It also compares the register
values seen from attached bpf program.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/include/linux/compiler.h | 4 +
.../selftests/bpf/prog_tests/uprobe_syscall.c | 163 ++++++++++++++++++
.../selftests/bpf/progs/uprobe_syscall.c | 15 ++
3 files changed, 182 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall.c

diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
index 8a63a9913495..6f7f22ac9da5 100644
--- a/tools/include/linux/compiler.h
+++ b/tools/include/linux/compiler.h
@@ -62,6 +62,10 @@
#define __nocf_check __attribute__((nocf_check))
#endif

+#ifndef __naked
+#define __naked __attribute__((__naked__))
+#endif
+
/* Are two types/vars the same type (ignoring qualifiers)? */
#ifndef __same_type
# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
new file mode 100644
index 000000000000..311ac19d8992
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+
+#ifdef __x86_64__
+
+#include <unistd.h>
+#include <asm/ptrace.h>
+#include <linux/compiler.h>
+#include "uprobe_syscall.skel.h"
+
+__naked unsigned long uretprobe_regs_trigger(void)
+{
+ asm volatile (
+ "movq $0xdeadbeef, %rax\n"
+ "ret\n"
+ );
+}
+
+__naked void uretprobe_regs(struct pt_regs *before, struct pt_regs *after)
+{
+ asm volatile (
+ "movq %r15, 0(%rdi)\n"
+ "movq %r14, 8(%rdi)\n"
+ "movq %r13, 16(%rdi)\n"
+ "movq %r12, 24(%rdi)\n"
+ "movq %rbp, 32(%rdi)\n"
+ "movq %rbx, 40(%rdi)\n"
+ "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"
+ "movq $0, 120(%rdi)\n" /* orig_rax */
+ "movq $0, 128(%rdi)\n" /* rip */
+ "movq $0, 136(%rdi)\n" /* cs */
+ "pushf\n"
+ "pop %rax\n"
+ "movq %rax, 144(%rdi)\n" /* eflags */
+ "movq %rsp, 152(%rdi)\n" /* rsp */
+ "movq $0, 160(%rdi)\n" /* ss */
+
+ /* save 2nd argument */
+ "pushq %rsi\n"
+ "call uretprobe_regs_trigger\n"
+
+ /* save return value and load 2nd argument pointer to rax */
+ "pushq %rax\n"
+ "movq 8(%rsp), %rax\n"
+
+ "movq %r15, 0(%rax)\n"
+ "movq %r14, 8(%rax)\n"
+ "movq %r13, 16(%rax)\n"
+ "movq %r12, 24(%rax)\n"
+ "movq %rbp, 32(%rax)\n"
+ "movq %rbx, 40(%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"
+ "movq $0, 120(%rax)\n" /* orig_rax */
+ "movq $0, 128(%rax)\n" /* rip */
+ "movq $0, 136(%rax)\n" /* cs */
+
+ /* restore return value and 2nd argument */
+ "pop %rax\n"
+ "pop %rsi\n"
+
+ "movq %rax, 80(%rsi)\n"
+
+ "pushf\n"
+ "pop %rax\n"
+
+ "movq %rax, 144(%rsi)\n" /* eflags */
+ "movq %rsp, 152(%rsi)\n" /* rsp */
+ "movq $0, 160(%rsi)\n" /* ss */
+ "ret\n"
+);
+}
+
+static void test_uretprobe_regs_equal(void)
+{
+ 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 int i, cnt;
+ int err;
+
+ 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"))
+ goto cleanup;
+
+ uretprobe_regs(&before, &after);
+
+ pp = (unsigned long *) &skel->bss->regs;
+ cnt = sizeof(before)/sizeof(*pb);
+
+ for (i = 0; i < cnt; i++) {
+ unsigned int offset = i * sizeof(unsigned long);
+
+ /*
+ * Check register before and after uretprobe_regs_trigger call
+ * that triggers the uretprobe.
+ */
+ switch (offset) {
+ case offsetof(struct pt_regs, rax):
+ ASSERT_EQ(pa[i], 0xdeadbeef, "return value");
+ break;
+ default:
+ if (!ASSERT_EQ(pb[i], pa[i], "register before-after value check"))
+ fprintf(stdout, "failed register offset %u\n", offset);
+ }
+
+ /*
+ * Check register seen from bpf program and register after
+ * uretprobe_regs_trigger call
+ */
+ switch (offset) {
+ /*
+ * These values will be different (not set in uretprobe_regs),
+ * we don't care.
+ */
+ case offsetof(struct pt_regs, orig_rax):
+ case offsetof(struct pt_regs, rip):
+ case offsetof(struct pt_regs, cs):
+ case offsetof(struct pt_regs, rsp):
+ case offsetof(struct pt_regs, ss):
+ break;
+ default:
+ if (!ASSERT_EQ(pp[i], pa[i], "register prog-after value check"))
+ fprintf(stdout, "failed register offset %u\n", offset);
+ }
+ }
+
+cleanup:
+ uprobe_syscall__destroy(skel);
+}
+#else
+static void test_uretprobe_regs_equal(void)
+{
+ test__skip();
+}
+#endif
+
+void test_uprobe_syscall(void)
+{
+ if (test__start_subtest("uretprobe_regs_equal"))
+ test_uretprobe_regs_equal();
+}
diff --git a/tools/testing/selftests/bpf/progs/uprobe_syscall.c b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
new file mode 100644
index 000000000000..8a4fa6c7ef59
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_syscall.c
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <string.h>
+
+struct pt_regs regs;
+
+char _license[] SEC("license") = "GPL";
+
+SEC("uretprobe//proc/self/exe:uretprobe_regs_trigger")
+int uretprobe(struct pt_regs *ctx)
+{
+ __builtin_memcpy(&regs, ctx, sizeof(regs));
+ return 0;
+}
--
2.44.0

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