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bpf: selftests: Add bpf_task_pt_regs() selftest

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This test retrieves the uprobe's pt_regs in two different ways and
compares the contents in an arch-agnostic way.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/5581eb8800f6625ec8813fe21e9dce1fbdef4937.1629772842.git.dxu@dxuuu.xyz
This commit is contained in:
Daniel Xu 2021-08-23 19:43:50 -07:00 • committed by Alexei Starovoitov
parent dd6e10fbd9
commit 576d47bb1a
2 changed files with 76 additions and 0 deletions
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47
tools/testing/selftests/bpf/prog_tests/task_pt_regs.c Normal file
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// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <test_progs.h>
#include <linux/ptrace.h>
#include "test_task_pt_regs.skel.h"
void test_task_pt_regs(void)
{
struct test_task_pt_regs *skel;
struct bpf_link *uprobe_link;
size_t uprobe_offset;
ssize_t base_addr;
bool match;
base_addr = get_base_addr();
if (!ASSERT_GT(base_addr, 0, "get_base_addr"))
return;
uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
skel = test_task_pt_regs__open_and_load();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
if (!ASSERT_OK_PTR(skel->bss, "check_bss"))
goto cleanup;
uprobe_link = bpf_program__attach_uprobe(skel->progs.handle_uprobe,
false /* retprobe */,
0 /* self pid */,
"/proc/self/exe",
uprobe_offset);
if (!ASSERT_OK_PTR(uprobe_link, "attach_uprobe"))
goto cleanup;
skel->links.handle_uprobe = uprobe_link;
/* trigger & validate uprobe */
get_base_addr();
if (!ASSERT_EQ(skel->bss->uprobe_res, 1, "check_uprobe_res"))
goto cleanup;
match = !memcmp(&skel->bss->current_regs, &skel->bss->ctx_regs,
sizeof(skel->bss->current_regs));
ASSERT_TRUE(match, "check_regs_match");
cleanup:
test_task_pt_regs__destroy(skel);
}

29
tools/testing/selftests/bpf/progs/test_task_pt_regs.c Normal file
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// SPDX-License-Identifier: GPL-2.0
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
struct pt_regs current_regs = {};
struct pt_regs ctx_regs = {};
int uprobe_res = 0;
SEC("uprobe/trigger_func")
int handle_uprobe(struct pt_regs *ctx)
{
struct task_struct *current;
struct pt_regs *regs;
current = bpf_get_current_task_btf();
regs = (struct pt_regs *) bpf_task_pt_regs(current);
__builtin_memcpy(&current_regs, regs, sizeof(*regs));
__builtin_memcpy(&ctx_regs, ctx, sizeof(*ctx));
/* Prove that uprobe was run */
uprobe_res = 1;
return 0;
}
char _license[] SEC("license") = "GPL";