From: Feng Zhou zhoufeng.zf@bytedance.com
Add support for integer type of accessing variable length array. Add a selftest to check it.
Feng Zhou (2): bpf: support access variable length array of integer type selftests/bpf: Add test to access integer type of variable array
kernel/bpf/btf.c | 8 +++++--- .../selftests/bpf/bpf_testmod/bpf_testmod.c | 20 +++++++++++++++++++ .../selftests/bpf/prog_tests/tracing_struct.c | 2 ++ .../selftests/bpf/progs/tracing_struct.c | 13 ++++++++++++ 4 files changed, 40 insertions(+), 3 deletions(-)
From: Feng Zhou zhoufeng.zf@bytedance.com
After this commit: bpf: Support variable length array in tracing programs (9c5f8a1008a1) Trace programs can access variable length array, but for structure type. This patch adds support for integer type.
Example: Hook load_balance struct sched_domain { ... unsigned long span[]; }
The access: sd->span[0].
Co-developed-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Feng Zhou zhoufeng.zf@bytedance.com --- kernel/bpf/btf.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 027f9f8a3551..a0887ee44e89 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6157,11 +6157,13 @@ static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf, if (off < moff) goto error;
- /* Only allow structure for now, can be relaxed for - * other types later. - */ + /* allow structure and integer */ t = btf_type_skip_modifiers(btf, array_elem->type, NULL); + + if (btf_type_is_int(t)) + return WALK_SCALAR; + if (!btf_type_is_struct(t)) goto error;
On Mon, Apr 17, 2023 at 04:07:48PM +0800, Feng zhou wrote:
From: Feng Zhou zhoufeng.zf@bytedance.com
After this commit: bpf: Support variable length array in tracing programs (9c5f8a1008a1) Trace programs can access variable length array, but for structure type. This patch adds support for integer type.
Example: Hook load_balance struct sched_domain { ... unsigned long span[]; }
The access: sd->span[0].
The use case makes sense. Please add it as a selftest. Either combine it with patch 2 or another patch 3. and then resubmit. Make sure to use [PATCH bpf-next] subject, so BPF CI knows how to test it.
在 2023/4/18 08:08, Alexei Starovoitov 写道:
On Mon, Apr 17, 2023 at 04:07:48PM +0800, Feng zhou wrote:
From: Feng Zhou zhoufeng.zf@bytedance.com
After this commit: bpf: Support variable length array in tracing programs (9c5f8a1008a1) Trace programs can access variable length array, but for structure type. This patch adds support for integer type.
Example: Hook load_balance struct sched_domain { ... unsigned long span[]; }
The access: sd->span[0].
The use case makes sense. Please add it as a selftest. Either combine it with patch 2 or another patch 3. and then resubmit. Make sure to use [PATCH bpf-next] subject, so BPF CI knows how to test it.
Will do, thanks.
From: Feng Zhou zhoufeng.zf@bytedance.com
Add prog test for accessing integer type of variable array in tracing program.
Co-developed-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Feng Zhou zhoufeng.zf@bytedance.com --- .../selftests/bpf/bpf_testmod/bpf_testmod.c | 20 +++++++++++++++++++ .../selftests/bpf/prog_tests/tracing_struct.c | 2 ++ .../selftests/bpf/progs/tracing_struct.c | 13 ++++++++++++ 3 files changed, 35 insertions(+)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c index fe847ebfb731..52785ba671e6 100644 --- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c +++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c @@ -28,6 +28,11 @@ struct bpf_testmod_struct_arg_2 { long b; };
+struct bpf_testmod_struct_arg_3 { + int a; + int b[]; +}; + __diag_push(); __diag_ignore_all("-Wmissing-prototypes", "Global functions as their definitions will be in bpf_testmod.ko BTF"); @@ -63,6 +68,12 @@ bpf_testmod_test_struct_arg_5(void) { return bpf_testmod_test_struct_arg_result; }
+noinline int +bpf_testmod_test_struct_arg_6(struct bpf_testmod_struct_arg_3 *a) { + bpf_testmod_test_struct_arg_result = a->b[0]; + return bpf_testmod_test_struct_arg_result; +} + __bpf_kfunc void bpf_testmod_test_mod_kfunc(int i) { @@ -195,6 +206,7 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj, }; struct bpf_testmod_struct_arg_1 struct_arg1 = {10}; struct bpf_testmod_struct_arg_2 struct_arg2 = {2, 3}; + struct bpf_testmod_struct_arg_3 *struct_arg3; int i = 1;
while (bpf_testmod_return_ptr(i)) @@ -206,6 +218,14 @@ bpf_testmod_test_read(struct file *file, struct kobject *kobj, (void)bpf_testmod_test_struct_arg_4(struct_arg1, 1, 2, 3, struct_arg2); (void)bpf_testmod_test_struct_arg_5();
+ struct_arg3 = kmalloc((sizeof(struct bpf_testmod_struct_arg_3) + + sizeof(int)), GFP_KERNEL); + if (struct_arg3 != NULL) { + struct_arg3->b[0] = 1; + (void)bpf_testmod_test_struct_arg_6(struct_arg3); + kfree(struct_arg3); + } + /* This is always true. Use the check to make sure the compiler * doesn't remove bpf_testmod_loop_test. */ diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_struct.c b/tools/testing/selftests/bpf/prog_tests/tracing_struct.c index 48dc9472e160..1c75a32186d6 100644 --- a/tools/testing/selftests/bpf/prog_tests/tracing_struct.c +++ b/tools/testing/selftests/bpf/prog_tests/tracing_struct.c @@ -53,6 +53,8 @@ static void test_fentry(void)
ASSERT_EQ(skel->bss->t5_ret, 1, "t5 ret");
+ ASSERT_EQ(skel->bss->t6, 1, "t6 ret"); + tracing_struct__detach(skel); destroy_skel: tracing_struct__destroy(skel); diff --git a/tools/testing/selftests/bpf/progs/tracing_struct.c b/tools/testing/selftests/bpf/progs/tracing_struct.c index e718f0ebee7d..c435a3a8328a 100644 --- a/tools/testing/selftests/bpf/progs/tracing_struct.c +++ b/tools/testing/selftests/bpf/progs/tracing_struct.c @@ -13,12 +13,18 @@ struct bpf_testmod_struct_arg_2 { long b; };
+struct bpf_testmod_struct_arg_3 { + int a; + int b[]; +}; + long t1_a_a, t1_a_b, t1_b, t1_c, t1_ret, t1_nregs; __u64 t1_reg0, t1_reg1, t1_reg2, t1_reg3; long t2_a, t2_b_a, t2_b_b, t2_c, t2_ret; long t3_a, t3_b, t3_c_a, t3_c_b, t3_ret; long t4_a_a, t4_b, t4_c, t4_d, t4_e_a, t4_e_b, t4_ret; long t5_ret; +int t6;
SEC("fentry/bpf_testmod_test_struct_arg_1") int BPF_PROG2(test_struct_arg_1, struct bpf_testmod_struct_arg_2, a, int, b, int, c) @@ -117,4 +123,11 @@ int BPF_PROG2(test_struct_arg_10, int, ret) return 0; }
+SEC("fentry/bpf_testmod_test_struct_arg_6") +int BPF_PROG2(test_struct_arg_11, struct bpf_testmod_struct_arg_3 *, a) +{ + t6 = a->b[0]; + return 0; +} + char _license[] SEC("license") = "GPL";
linux-kselftest-mirror@lists.linaro.org
-
Alexei Starovoitov -
Feng Zhou -
Feng zhou