* [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64
@ 2021-09-02 9:09 Jean-Philippe Brucker
2021-09-02 18:32 ` Daniel Xu
2021-09-02 19:13 ` Alexei Starovoitov
0 siblings, 2 replies; 5+ messages in thread
From: Jean-Philippe Brucker @ 2021-09-02 9:09 UTC (permalink / raw)
To: ast, daniel, andrii
Cc: kafai, songliubraving, yhs, john.fastabend, kpsingh, dxu, bpf,
linux-kselftest, shuah, Jean-Philippe Brucker
struct pt_regs is not exported to userspace on all archs. arm64 and s390
export "user_pt_regs" instead, which causes build failure at the moment:
progs/test_task_pt_regs.c:8:16: error: variable has incomplete type 'struct pt_regs'
struct pt_regs current_regs = {};
Use the multi-arch macros defined by tools/lib/bpf/bpf_tracing.h to copy
the pt_regs into a locally-defined struct.
Copying the user_pt_regs struct on arm64 wouldn't work because the
struct is too large and the compiler complains about using too much
stack.
Fixes: 576d47bb1a92 ("bpf: selftests: Add bpf_task_pt_regs() selftest")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
.../selftests/bpf/bpf_pt_regs_helpers.h | 30 +++++++++++++++++++
.../selftests/bpf/prog_tests/task_pt_regs.c | 1 +
.../selftests/bpf/progs/test_task_pt_regs.c | 10 ++++---
3 files changed, 37 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
diff --git a/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h b/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
new file mode 100644
index 000000000000..7531f4824ead
--- /dev/null
+++ b/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __BPF_PT_REGS_HELPERS
+#define __BPF_PT_REGS_HELPERS
+
+#include <bpf/bpf_tracing.h>
+
+struct bpf_pt_regs {
+ unsigned long long parm[5];
+ unsigned long long ret;
+ unsigned long long fp;
+ unsigned long long rc;
+ unsigned long long sp;
+ unsigned long long ip;
+};
+
+static inline void bpf_copy_pt_regs(struct bpf_pt_regs *dest, struct pt_regs *src)
+{
+ dest->parm[0] = PT_REGS_PARM1(src);
+ dest->parm[1] = PT_REGS_PARM2(src);
+ dest->parm[2] = PT_REGS_PARM3(src);
+ dest->parm[3] = PT_REGS_PARM4(src);
+ dest->parm[4] = PT_REGS_PARM5(src);
+ dest->ret = PT_REGS_RET(src);
+ dest->fp = PT_REGS_FP(src);
+ dest->rc = PT_REGS_RC(src);
+ dest->sp = PT_REGS_SP(src);
+ dest->ip = PT_REGS_IP(src);
+}
+
+#endif /* __BPF_PT_REGS_HELPERS */
diff --git a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
index 53f0e0fa1a53..196453b75937 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
+++ b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
@@ -2,6 +2,7 @@
#define _GNU_SOURCE
#include <test_progs.h>
#include <linux/ptrace.h>
+#include "bpf_pt_regs_helpers.h"
#include "test_task_pt_regs.skel.h"
void test_task_pt_regs(void)
diff --git a/tools/testing/selftests/bpf/progs/test_task_pt_regs.c b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
index 6c059f1cfa1b..348da3509093 100644
--- a/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
+++ b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
@@ -5,8 +5,10 @@
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
-struct pt_regs current_regs = {};
-struct pt_regs ctx_regs = {};
+#include "bpf_pt_regs_helpers.h"
+
+struct bpf_pt_regs current_regs = {};
+struct bpf_pt_regs ctx_regs = {};
int uprobe_res = 0;
SEC("uprobe/trigger_func")
@@ -17,8 +19,8 @@ int handle_uprobe(struct pt_regs *ctx)
current = bpf_get_current_task_btf();
regs = (struct pt_regs *) bpf_task_pt_regs(current);
- __builtin_memcpy(¤t_regs, regs, sizeof(*regs));
- __builtin_memcpy(&ctx_regs, ctx, sizeof(*ctx));
+ bpf_copy_pt_regs(¤t_regs, regs);
+ bpf_copy_pt_regs(&ctx_regs, ctx);
/* Prove that uprobe was run */
uprobe_res = 1;
--
2.33.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64
2021-09-02 9:09 [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64 Jean-Philippe Brucker
@ 2021-09-02 18:32 ` Daniel Xu
2021-09-02 19:13 ` Alexei Starovoitov
1 sibling, 0 replies; 5+ messages in thread
From: Daniel Xu @ 2021-09-02 18:32 UTC (permalink / raw)
To: Jean-Philippe Brucker
Cc: ast, daniel, andrii, kafai, songliubraving, yhs, john.fastabend,
kpsingh, bpf, linux-kselftest, shuah
On Thu, Sep 02, 2021 at 11:09:26AM +0200, Jean-Philippe Brucker wrote:
> struct pt_regs is not exported to userspace on all archs. arm64 and s390
> export "user_pt_regs" instead, which causes build failure at the moment:
>
> progs/test_task_pt_regs.c:8:16: error: variable has incomplete type 'struct pt_regs'
> struct pt_regs current_regs = {};
>
> Use the multi-arch macros defined by tools/lib/bpf/bpf_tracing.h to copy
> the pt_regs into a locally-defined struct.
>
> Copying the user_pt_regs struct on arm64 wouldn't work because the
> struct is too large and the compiler complains about using too much
> stack.
>
> Fixes: 576d47bb1a92 ("bpf: selftests: Add bpf_task_pt_regs() selftest")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
> .../selftests/bpf/bpf_pt_regs_helpers.h | 30 +++++++++++++++++++
> .../selftests/bpf/prog_tests/task_pt_regs.c | 1 +
> .../selftests/bpf/progs/test_task_pt_regs.c | 10 ++++---
> 3 files changed, 37 insertions(+), 4 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
Acked-by: Daniel Xu <dxu@dxuuu.xyz>
[...]
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64
2021-09-02 9:09 [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64 Jean-Philippe Brucker
2021-09-02 18:32 ` Daniel Xu
@ 2021-09-02 19:13 ` Alexei Starovoitov
2021-09-03 12:33 ` Jean-Philippe Brucker
1 sibling, 1 reply; 5+ messages in thread
From: Alexei Starovoitov @ 2021-09-02 19:13 UTC (permalink / raw)
To: Jean-Philippe Brucker
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Daniel Xu, bpf, open list:KERNEL SELFTEST FRAMEWORK,
Shuah Khan
On Thu, Sep 2, 2021 at 2:08 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> struct pt_regs is not exported to userspace on all archs. arm64 and s390
> export "user_pt_regs" instead, which causes build failure at the moment:
>
> progs/test_task_pt_regs.c:8:16: error: variable has incomplete type 'struct pt_regs'
> struct pt_regs current_regs = {};
Right, which is 'bpf_user_pt_regs_t'.
It's defined for all archs and arm64/s390/ppc/risv define it
differently from pt_regs.
>
> Use the multi-arch macros defined by tools/lib/bpf/bpf_tracing.h to copy
> the pt_regs into a locally-defined struct.
>
> Copying the user_pt_regs struct on arm64 wouldn't work because the
> struct is too large and the compiler complains about using too much
> stack.
That's a different issue.
I think the cleaner fix would be to make the test use
bpf_user_pt_regs_t instead.
> Fixes: 576d47bb1a92 ("bpf: selftests: Add bpf_task_pt_regs() selftest")
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
> .../selftests/bpf/bpf_pt_regs_helpers.h | 30 +++++++++++++++++++
> .../selftests/bpf/prog_tests/task_pt_regs.c | 1 +
> .../selftests/bpf/progs/test_task_pt_regs.c | 10 ++++---
> 3 files changed, 37 insertions(+), 4 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
>
> diff --git a/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h b/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
> new file mode 100644
> index 000000000000..7531f4824ead
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/bpf_pt_regs_helpers.h
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __BPF_PT_REGS_HELPERS
> +#define __BPF_PT_REGS_HELPERS
> +
> +#include <bpf/bpf_tracing.h>
> +
> +struct bpf_pt_regs {
> + unsigned long long parm[5];
> + unsigned long long ret;
> + unsigned long long fp;
> + unsigned long long rc;
> + unsigned long long sp;
> + unsigned long long ip;
> +};
> +
> +static inline void bpf_copy_pt_regs(struct bpf_pt_regs *dest, struct pt_regs *src)
> +{
> + dest->parm[0] = PT_REGS_PARM1(src);
> + dest->parm[1] = PT_REGS_PARM2(src);
> + dest->parm[2] = PT_REGS_PARM3(src);
> + dest->parm[3] = PT_REGS_PARM4(src);
> + dest->parm[4] = PT_REGS_PARM5(src);
> + dest->ret = PT_REGS_RET(src);
> + dest->fp = PT_REGS_FP(src);
> + dest->rc = PT_REGS_RC(src);
> + dest->sp = PT_REGS_SP(src);
> + dest->ip = PT_REGS_IP(src);
> +}
> +
> +#endif /* __BPF_PT_REGS_HELPERS */
> diff --git a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> index 53f0e0fa1a53..196453b75937 100644
> --- a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> +++ b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> @@ -2,6 +2,7 @@
> #define _GNU_SOURCE
> #include <test_progs.h>
> #include <linux/ptrace.h>
> +#include "bpf_pt_regs_helpers.h"
> #include "test_task_pt_regs.skel.h"
>
> void test_task_pt_regs(void)
> diff --git a/tools/testing/selftests/bpf/progs/test_task_pt_regs.c b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
> index 6c059f1cfa1b..348da3509093 100644
> --- a/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
> +++ b/tools/testing/selftests/bpf/progs/test_task_pt_regs.c
> @@ -5,8 +5,10 @@
> #include <bpf/bpf_helpers.h>
> #include <bpf/bpf_tracing.h>
>
> -struct pt_regs current_regs = {};
> -struct pt_regs ctx_regs = {};
> +#include "bpf_pt_regs_helpers.h"
> +
> +struct bpf_pt_regs current_regs = {};
> +struct bpf_pt_regs ctx_regs = {};
> int uprobe_res = 0;
>
> SEC("uprobe/trigger_func")
> @@ -17,8 +19,8 @@ int handle_uprobe(struct pt_regs *ctx)
>
> current = bpf_get_current_task_btf();
> regs = (struct pt_regs *) bpf_task_pt_regs(current);
> - __builtin_memcpy(¤t_regs, regs, sizeof(*regs));
> - __builtin_memcpy(&ctx_regs, ctx, sizeof(*ctx));
> + bpf_copy_pt_regs(¤t_regs, regs);
> + bpf_copy_pt_regs(&ctx_regs, ctx);
>
> /* Prove that uprobe was run */
> uprobe_res = 1;
> --
> 2.33.0
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64
2021-09-02 19:13 ` Alexei Starovoitov
@ 2021-09-03 12:33 ` Jean-Philippe Brucker
2021-09-03 16:51 ` Andrii Nakryiko
0 siblings, 1 reply; 5+ messages in thread
From: Jean-Philippe Brucker @ 2021-09-03 12:33 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
KP Singh, Daniel Xu, bpf, open list:KERNEL SELFTEST FRAMEWORK,
Shuah Khan
On Thu, Sep 02, 2021 at 12:13:40PM -0700, Alexei Starovoitov wrote:
> On Thu, Sep 2, 2021 at 2:08 AM Jean-Philippe Brucker
> <jean-philippe@linaro.org> wrote:
> >
> > struct pt_regs is not exported to userspace on all archs. arm64 and s390
> > export "user_pt_regs" instead, which causes build failure at the moment:
> >
> > progs/test_task_pt_regs.c:8:16: error: variable has incomplete type 'struct pt_regs'
> > struct pt_regs current_regs = {};
>
> Right, which is 'bpf_user_pt_regs_t'.
> It's defined for all archs and arm64/s390/ppc/risv define it
> differently from pt_regs.
>
> >
> > Use the multi-arch macros defined by tools/lib/bpf/bpf_tracing.h to copy
> > the pt_regs into a locally-defined struct.
> >
> > Copying the user_pt_regs struct on arm64 wouldn't work because the
> > struct is too large and the compiler complains about using too much
> > stack.
>
> That's a different issue.
It does work when doing an implicit copy (current_regs = *regs) rather
than using __builtin_memcpy(). Don't know why but I'll take it.
> I think the cleaner fix would be to make the test use
> bpf_user_pt_regs_t instead.
Right, although that comes with another complication. We end up including
tools/include/uapi/asm/bpf_perf_event.h which requires the compiler
builtins "__aarch64__", "__s390__", etc. Those are not defined with
"clang -target bpf" so I have to add them to the command line.
I'll resend with your suggestion but this patch is simpler.
Thanks,
Jean
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64
2021-09-03 12:33 ` Jean-Philippe Brucker
@ 2021-09-03 16:51 ` Andrii Nakryiko
0 siblings, 0 replies; 5+ messages in thread
From: Andrii Nakryiko @ 2021-09-03 16:51 UTC (permalink / raw)
To: Jean-Philippe Brucker
Cc: Alexei Starovoitov, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, Daniel Xu, bpf,
open list:KERNEL SELFTEST FRAMEWORK, Shuah Khan
On Fri, Sep 3, 2021 at 5:31 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> On Thu, Sep 02, 2021 at 12:13:40PM -0700, Alexei Starovoitov wrote:
> > On Thu, Sep 2, 2021 at 2:08 AM Jean-Philippe Brucker
> > <jean-philippe@linaro.org> wrote:
> > >
> > > struct pt_regs is not exported to userspace on all archs. arm64 and s390
> > > export "user_pt_regs" instead, which causes build failure at the moment:
> > >
> > > progs/test_task_pt_regs.c:8:16: error: variable has incomplete type 'struct pt_regs'
> > > struct pt_regs current_regs = {};
> >
> > Right, which is 'bpf_user_pt_regs_t'.
> > It's defined for all archs and arm64/s390/ppc/risv define it
> > differently from pt_regs.
> >
> > >
> > > Use the multi-arch macros defined by tools/lib/bpf/bpf_tracing.h to copy
> > > the pt_regs into a locally-defined struct.
> > >
> > > Copying the user_pt_regs struct on arm64 wouldn't work because the
> > > struct is too large and the compiler complains about using too much
> > > stack.
> >
> > That's a different issue.
>
> It does work when doing an implicit copy (current_regs = *regs) rather
> than using __builtin_memcpy(). Don't know why but I'll take it.
>
> > I think the cleaner fix would be to make the test use
> > bpf_user_pt_regs_t instead.
>
> Right, although that comes with another complication. We end up including
> tools/include/uapi/asm/bpf_perf_event.h which requires the compiler
> builtins "__aarch64__", "__s390__", etc. Those are not defined with
> "clang -target bpf" so I have to add them to the command line.
> I'll resend with your suggestion but this patch is simpler.
>
The test doesn't care about struct pt_regs type itself, it only cares
to check that contents of captured pt_regs are the same.
We can use CO-RE to check whether user_pt_regs or pt_regs exists in
the kernel. We can also use bpf_core_type_size() to know exactly how
many bytes we want to capture. And then just use
bpf_probe_read_kernel() as memcpy() equivalent to capture bytes. This
should work on all architectures.
> Thanks,
> Jean
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-09-02 9:09 [PATCH bpf-next] selftests/bpf: Fix build of task_pt_regs tests for arm64 Jean-Philippe Brucker
2021-09-02 18:32 ` Daniel Xu
2021-09-02 19:13 ` Alexei Starovoitov
2021-09-03 12:33 ` Jean-Philippe Brucker
2021-09-03 16:51 ` Andrii Nakryiko
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