* [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
@ 2021-01-12 9:15 Gilad Reti
2021-01-12 14:55 ` KP Singh
0 siblings, 1 reply; 7+ messages in thread
From: Gilad Reti @ 2021-01-12 9:15 UTC (permalink / raw)
To: bpf
Cc: gilad.reti, Shuah Khan, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, KP Singh, linux-kselftest, netdev, linux-kernel
Add test to check that the verifier is able to recognize spilling of
PTR_TO_MEM registers.
The patch was partially contibuted by CyberArk Software, Inc.
Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
---
tools/testing/selftests/bpf/test_verifier.c | 12 +++++++-
.../selftests/bpf/verifier/spill_fill.c | 30 +++++++++++++++++++
2 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index 777a81404fdb..f8569f04064b 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -50,7 +50,7 @@
#define MAX_INSNS BPF_MAXINSNS
#define MAX_TEST_INSNS 1000000
#define MAX_FIXUPS 8
-#define MAX_NR_MAPS 20
+#define MAX_NR_MAPS 21
#define MAX_TEST_RUNS 8
#define POINTER_VALUE 0xcafe4all
#define TEST_DATA_LEN 64
@@ -87,6 +87,7 @@ struct bpf_test {
int fixup_sk_storage_map[MAX_FIXUPS];
int fixup_map_event_output[MAX_FIXUPS];
int fixup_map_reuseport_array[MAX_FIXUPS];
+ int fixup_map_ringbuf[MAX_FIXUPS];
const char *errstr;
const char *errstr_unpriv;
uint32_t insn_processed;
@@ -640,6 +641,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
int *fixup_sk_storage_map = test->fixup_sk_storage_map;
int *fixup_map_event_output = test->fixup_map_event_output;
int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
+ int *fixup_map_ringbuf = test->fixup_map_ringbuf;
if (test->fill_helper) {
test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -817,6 +819,14 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
fixup_map_reuseport_array++;
} while (*fixup_map_reuseport_array);
}
+ if (*fixup_map_ringbuf) {
+ map_fds[20] = create_map(BPF_MAP_TYPE_RINGBUF, 0,
+ 0, 4096);
+ do {
+ prog[*fixup_map_ringbuf].imm = map_fds[20];
+ fixup_map_ringbuf++;
+ } while (*fixup_map_ringbuf);
+ }
}
struct libcap {
diff --git a/tools/testing/selftests/bpf/verifier/spill_fill.c b/tools/testing/selftests/bpf/verifier/spill_fill.c
index 45d43bf82f26..1833b6c730dd 100644
--- a/tools/testing/selftests/bpf/verifier/spill_fill.c
+++ b/tools/testing/selftests/bpf/verifier/spill_fill.c
@@ -28,6 +28,36 @@
.result = ACCEPT,
.result_unpriv = ACCEPT,
},
+{
+ "check valid spill/fill, ptr to mem",
+ .insns = {
+ /* reserve 8 byte ringbuf memory */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_MOV64_IMM(BPF_REG_2, 8),
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
+ /* store a pointer to the reserved memory in R6 */
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+ /* check whether the reservation was successful */
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
+ /* spill R6(mem) into the stack */
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
+ /* fill it back in R7 */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
+ /* should be able to access *(R7) = 0 */
+ BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
+ /* submit the reserved rungbuf memory */
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_ringbuf = { 1 },
+ .result = ACCEPT,
+ .result_unpriv = ACCEPT,
+},
{
"check corrupted spill/fill",
.insns = {
--
2.27.0
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 9:15 [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill Gilad Reti
@ 2021-01-12 14:55 ` KP Singh
2021-01-12 15:35 ` Gilad Reti
0 siblings, 1 reply; 7+ messages in thread
From: KP Singh @ 2021-01-12 14:55 UTC (permalink / raw)
To: Gilad Reti
Cc: bpf, Shuah Khan, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, linux-kselftest, Networking, open list
On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
>
> Add test to check that the verifier is able to recognize spilling of
> PTR_TO_MEM registers.
>
It would be nice to have some explanation of what the test does to
recognize the spilling of the PTR_TO_MEM registers in the commit
log as well.
Would it be possible to augment an existing test_progs
program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
this functionality?
> The patch was partially contibuted by CyberArk Software, Inc.
>
> Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
> ---
> tools/testing/selftests/bpf/test_verifier.c | 12 +++++++-
> .../selftests/bpf/verifier/spill_fill.c | 30 +++++++++++++++++++
> 2 files changed, 41 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> index 777a81404fdb..f8569f04064b 100644
> --- a/tools/testing/selftests/bpf/test_verifier.c
> +++ b/tools/testing/selftests/bpf/test_verifier.c
> @@ -50,7 +50,7 @@
> #define MAX_INSNS BPF_MAXINSNS
> #define MAX_TEST_INSNS 1000000
> #define MAX_FIXUPS 8
> -#define MAX_NR_MAPS 20
> +#define MAX_NR_MAPS 21
> #define MAX_TEST_RUNS 8
> #define POINTER_VALUE 0xcafe4all
> #define TEST_DATA_LEN 64
> @@ -87,6 +87,7 @@ struct bpf_test {
> int fixup_sk_storage_map[MAX_FIXUPS];
> int fixup_map_event_output[MAX_FIXUPS];
> int fixup_map_reuseport_array[MAX_FIXUPS];
> + int fixup_map_ringbuf[MAX_FIXUPS];
> const char *errstr;
> const char *errstr_unpriv;
> uint32_t insn_processed;
> @@ -640,6 +641,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> int *fixup_sk_storage_map = test->fixup_sk_storage_map;
> int *fixup_map_event_output = test->fixup_map_event_output;
> int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
> + int *fixup_map_ringbuf = test->fixup_map_ringbuf;
>
> if (test->fill_helper) {
> test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
> @@ -817,6 +819,14 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> fixup_map_reuseport_array++;
> } while (*fixup_map_reuseport_array);
> }
> + if (*fixup_map_ringbuf) {
> + map_fds[20] = create_map(BPF_MAP_TYPE_RINGBUF, 0,
> + 0, 4096);
> + do {
> + prog[*fixup_map_ringbuf].imm = map_fds[20];
> + fixup_map_ringbuf++;
> + } while (*fixup_map_ringbuf);
> + }
> }
>
> struct libcap {
> diff --git a/tools/testing/selftests/bpf/verifier/spill_fill.c b/tools/testing/selftests/bpf/verifier/spill_fill.c
> index 45d43bf82f26..1833b6c730dd 100644
> --- a/tools/testing/selftests/bpf/verifier/spill_fill.c
> +++ b/tools/testing/selftests/bpf/verifier/spill_fill.c
> @@ -28,6 +28,36 @@
> .result = ACCEPT,
> .result_unpriv = ACCEPT,
> },
> +{
> + "check valid spill/fill, ptr to mem",
> + .insns = {
> + /* reserve 8 byte ringbuf memory */
> + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
> + BPF_LD_MAP_FD(BPF_REG_1, 0),
> + BPF_MOV64_IMM(BPF_REG_2, 8),
> + BPF_MOV64_IMM(BPF_REG_3, 0),
> + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
> + /* store a pointer to the reserved memory in R6 */
> + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
> + /* check whether the reservation was successful */
> + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
> + /* spill R6(mem) into the stack */
> + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
> + /* fill it back in R7 */
> + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
> + /* should be able to access *(R7) = 0 */
> + BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
> + /* submit the reserved rungbuf memory */
> + BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
> + BPF_MOV64_IMM(BPF_REG_2, 0),
> + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
> + BPF_MOV64_IMM(BPF_REG_0, 0),
> + BPF_EXIT_INSN(),
> + },
> + .fixup_map_ringbuf = { 1 },
> + .result = ACCEPT,
> + .result_unpriv = ACCEPT,
> +},
> {
> "check corrupted spill/fill",
> .insns = {
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 14:55 ` KP Singh
@ 2021-01-12 15:35 ` Gilad Reti
2021-01-12 15:43 ` Daniel Borkmann
0 siblings, 1 reply; 7+ messages in thread
From: Gilad Reti @ 2021-01-12 15:35 UTC (permalink / raw)
To: KP Singh
Cc: bpf, Shuah Khan, Alexei Starovoitov, Daniel Borkmann,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, linux-kselftest, Networking, open list
On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote:
>
> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
> >
> > Add test to check that the verifier is able to recognize spilling of
> > PTR_TO_MEM registers.
> >
>
> It would be nice to have some explanation of what the test does to
> recognize the spilling of the PTR_TO_MEM registers in the commit
> log as well.
>
> Would it be possible to augment an existing test_progs
> program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
> this functionality?
>
It may be possible, but from what I understood from Daniel's comment here
https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
the test should be a part of the verifier tests (which is reasonable
to me since it is
a verifier bugfix)
>
>
> > The patch was partially contibuted by CyberArk Software, Inc.
> >
> > Signed-off-by: Gilad Reti <gilad.reti@gmail.com>
> > ---
> > tools/testing/selftests/bpf/test_verifier.c | 12 +++++++-
> > .../selftests/bpf/verifier/spill_fill.c | 30 +++++++++++++++++++
> > 2 files changed, 41 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
> > index 777a81404fdb..f8569f04064b 100644
> > --- a/tools/testing/selftests/bpf/test_verifier.c
> > +++ b/tools/testing/selftests/bpf/test_verifier.c
> > @@ -50,7 +50,7 @@
> > #define MAX_INSNS BPF_MAXINSNS
> > #define MAX_TEST_INSNS 1000000
> > #define MAX_FIXUPS 8
> > -#define MAX_NR_MAPS 20
> > +#define MAX_NR_MAPS 21
> > #define MAX_TEST_RUNS 8
> > #define POINTER_VALUE 0xcafe4all
> > #define TEST_DATA_LEN 64
> > @@ -87,6 +87,7 @@ struct bpf_test {
> > int fixup_sk_storage_map[MAX_FIXUPS];
> > int fixup_map_event_output[MAX_FIXUPS];
> > int fixup_map_reuseport_array[MAX_FIXUPS];
> > + int fixup_map_ringbuf[MAX_FIXUPS];
> > const char *errstr;
> > const char *errstr_unpriv;
> > uint32_t insn_processed;
> > @@ -640,6 +641,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> > int *fixup_sk_storage_map = test->fixup_sk_storage_map;
> > int *fixup_map_event_output = test->fixup_map_event_output;
> > int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
> > + int *fixup_map_ringbuf = test->fixup_map_ringbuf;
> >
> > if (test->fill_helper) {
> > test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
> > @@ -817,6 +819,14 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
> > fixup_map_reuseport_array++;
> > } while (*fixup_map_reuseport_array);
> > }
> > + if (*fixup_map_ringbuf) {
> > + map_fds[20] = create_map(BPF_MAP_TYPE_RINGBUF, 0,
> > + 0, 4096);
> > + do {
> > + prog[*fixup_map_ringbuf].imm = map_fds[20];
> > + fixup_map_ringbuf++;
> > + } while (*fixup_map_ringbuf);
> > + }
> > }
> >
> > struct libcap {
> > diff --git a/tools/testing/selftests/bpf/verifier/spill_fill.c b/tools/testing/selftests/bpf/verifier/spill_fill.c
> > index 45d43bf82f26..1833b6c730dd 100644
> > --- a/tools/testing/selftests/bpf/verifier/spill_fill.c
> > +++ b/tools/testing/selftests/bpf/verifier/spill_fill.c
> > @@ -28,6 +28,36 @@
> > .result = ACCEPT,
> > .result_unpriv = ACCEPT,
> > },
> > +{
> > + "check valid spill/fill, ptr to mem",
> > + .insns = {
> > + /* reserve 8 byte ringbuf memory */
> > + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
> > + BPF_LD_MAP_FD(BPF_REG_1, 0),
> > + BPF_MOV64_IMM(BPF_REG_2, 8),
> > + BPF_MOV64_IMM(BPF_REG_3, 0),
> > + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
> > + /* store a pointer to the reserved memory in R6 */
> > + BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
> > + /* check whether the reservation was successful */
> > + BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
> > + /* spill R6(mem) into the stack */
> > + BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
> > + /* fill it back in R7 */
> > + BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
> > + /* should be able to access *(R7) = 0 */
> > + BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
> > + /* submit the reserved rungbuf memory */
> > + BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
> > + BPF_MOV64_IMM(BPF_REG_2, 0),
> > + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
> > + BPF_MOV64_IMM(BPF_REG_0, 0),
> > + BPF_EXIT_INSN(),
> > + },
> > + .fixup_map_ringbuf = { 1 },
> > + .result = ACCEPT,
> > + .result_unpriv = ACCEPT,
> > +},
> > {
> > "check corrupted spill/fill",
> > .insns = {
> > --
> > 2.27.0
> >
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 15:35 ` Gilad Reti
@ 2021-01-12 15:43 ` Daniel Borkmann
2021-01-12 16:17 ` KP Singh
2021-01-12 16:59 ` Yonghong Song
0 siblings, 2 replies; 7+ messages in thread
From: Daniel Borkmann @ 2021-01-12 15:43 UTC (permalink / raw)
To: Gilad Reti, KP Singh
Cc: bpf, Shuah Khan, Alexei Starovoitov, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
linux-kselftest, Networking, open list
On 1/12/21 4:35 PM, Gilad Reti wrote:
> On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote:
>> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
>>>
>>> Add test to check that the verifier is able to recognize spilling of
>>> PTR_TO_MEM registers.
>>
>> It would be nice to have some explanation of what the test does to
>> recognize the spilling of the PTR_TO_MEM registers in the commit
>> log as well.
>>
>> Would it be possible to augment an existing test_progs
>> program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
>> this functionality?
How would you guarantee that LLVM generates the spill/fill, via inline asm?
> It may be possible, but from what I understood from Daniel's comment here
>
> https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
>
> the test should be a part of the verifier tests (which is reasonable
> to me since it is
> a verifier bugfix)
Yeah, the test_verifier case as you have is definitely the most straight
forward way to add coverage in this case.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 15:43 ` Daniel Borkmann
@ 2021-01-12 16:17 ` KP Singh
2021-01-12 16:24 ` Gilad Reti
2021-01-12 16:59 ` Yonghong Song
1 sibling, 1 reply; 7+ messages in thread
From: KP Singh @ 2021-01-12 16:17 UTC (permalink / raw)
To: Daniel Borkmann
Cc: Gilad Reti, bpf, Shuah Khan, Alexei Starovoitov, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
linux-kselftest, Networking, open list
On Tue, Jan 12, 2021 at 4:43 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 1/12/21 4:35 PM, Gilad Reti wrote:
> > On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote:
> >> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
> >>>
> >>> Add test to check that the verifier is able to recognize spilling of
> >>> PTR_TO_MEM registers.
> >>
> >> It would be nice to have some explanation of what the test does to
> >> recognize the spilling of the PTR_TO_MEM registers in the commit
> >> log as well.
> >>
> >> Would it be possible to augment an existing test_progs
> >> program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
> >> this functionality?
>
> How would you guarantee that LLVM generates the spill/fill, via inline asm?
Yeah, I guess there is no sure-shot way to do it and, adding inline asm would
just be doing the same thing as this verifier test. You can ignore me
on this one :)
It would, however, be nice to have a better description about what the test is
actually doing./
>
> > It may be possible, but from what I understood from Daniel's comment here
> >
> > https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
> >
> > the test should be a part of the verifier tests (which is reasonable
> > to me since it is
> > a verifier bugfix)
>
> Yeah, the test_verifier case as you have is definitely the most straight
> forward way to add coverage in this case.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 16:17 ` KP Singh
@ 2021-01-12 16:24 ` Gilad Reti
0 siblings, 0 replies; 7+ messages in thread
From: Gilad Reti @ 2021-01-12 16:24 UTC (permalink / raw)
To: KP Singh
Cc: Daniel Borkmann, bpf, Shuah Khan, Alexei Starovoitov,
Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
John Fastabend, linux-kselftest, Networking, open list
On Tue, Jan 12, 2021 at 6:17 PM KP Singh <kpsingh@kernel.org> wrote:
>
> On Tue, Jan 12, 2021 at 4:43 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
> >
> > On 1/12/21 4:35 PM, Gilad Reti wrote:
> > > On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote:
> > >> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com> wrote:
> > >>>
> > >>> Add test to check that the verifier is able to recognize spilling of
> > >>> PTR_TO_MEM registers.
> > >>
> > >> It would be nice to have some explanation of what the test does to
> > >> recognize the spilling of the PTR_TO_MEM registers in the commit
> > >> log as well.
> > >>
> > >> Would it be possible to augment an existing test_progs
> > >> program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
> > >> this functionality?
> >
> > How would you guarantee that LLVM generates the spill/fill, via inline asm?
>
> Yeah, I guess there is no sure-shot way to do it and, adding inline asm would
> just be doing the same thing as this verifier test. You can ignore me
> on this one :)
>
> It would, however, be nice to have a better description about what the test is
> actually doing./
>
>
I will re-submit the patch tomorrow. Thank you all for your patience.
> >
> > > It may be possible, but from what I understood from Daniel's comment here
> > >
> > > https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
> > >
> > > the test should be a part of the verifier tests (which is reasonable
> > > to me since it is
> > > a verifier bugfix)
> >
> > Yeah, the test_verifier case as you have is definitely the most straight
> > forward way to add coverage in this case.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill
2021-01-12 15:43 ` Daniel Borkmann
2021-01-12 16:17 ` KP Singh
@ 2021-01-12 16:59 ` Yonghong Song
1 sibling, 0 replies; 7+ messages in thread
From: Yonghong Song @ 2021-01-12 16:59 UTC (permalink / raw)
To: Daniel Borkmann, Gilad Reti, KP Singh
Cc: bpf, Shuah Khan, Alexei Starovoitov, Andrii Nakryiko,
Martin KaFai Lau, Song Liu, John Fastabend, linux-kselftest,
Networking, open list
On 1/12/21 7:43 AM, Daniel Borkmann wrote:
> On 1/12/21 4:35 PM, Gilad Reti wrote:
>> On Tue, Jan 12, 2021 at 4:56 PM KP Singh <kpsingh@kernel.org> wrote:
>>> On Tue, Jan 12, 2021 at 10:16 AM Gilad Reti <gilad.reti@gmail.com>
>>> wrote:
>>>>
>>>> Add test to check that the verifier is able to recognize spilling of
>>>> PTR_TO_MEM registers.
>>>
>>> It would be nice to have some explanation of what the test does to
>>> recognize the spilling of the PTR_TO_MEM registers in the commit
>>> log as well.
>>>
>>> Would it be possible to augment an existing test_progs
>>> program like tools/testing/selftests/bpf/progs/test_ringbuf.c to test
>>> this functionality?
>
> How would you guarantee that LLVM generates the spill/fill, via inline asm?
You can make the following change to force the return value ("sample"
here) of bpf_ringbuf_reserve() to spill on the stack.
diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf.c
b/tools/testing/selftests/bpf/progs/test_ringbuf.c
index 8ba9959b036b..011521170856 100644
--- a/tools/testing/selftests/bpf/progs/test_ringbuf.c
+++ b/tools/testing/selftests/bpf/progs/test_ringbuf.c
@@ -40,7 +40,7 @@ SEC("tp/syscalls/sys_enter_getpgid")
int test_ringbuf(void *ctx)
{
int cur_pid = bpf_get_current_pid_tgid() >> 32;
- struct sample *sample;
+ struct sample * volatile sample;
int zero = 0;
if (cur_pid != pid)
This change will cause verifier failure without Patch #1.
>
>> It may be possible, but from what I understood from Daniel's comment here
>>
>> https://lore.kernel.org/bpf/17629073-4fab-a922-ecc3-25b019960f44@iogearbox.net/
>>
>>
>> the test should be a part of the verifier tests (which is reasonable
>> to me since it is
>> a verifier bugfix)
>
> Yeah, the test_verifier case as you have is definitely the most straight
> forward way to add coverage in this case.
^ permalink raw reply related [flat|nested] 7+ messages in thread
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2021-01-12 9:15 [PATCH 2/2] selftests/bpf: add verifier test for PTR_TO_MEM spill Gilad Reti
2021-01-12 14:55 ` KP Singh
2021-01-12 15:35 ` Gilad Reti
2021-01-12 15:43 ` Daniel Borkmann
2021-01-12 16:17 ` KP Singh
2021-01-12 16:24 ` Gilad Reti
2021-01-12 16:59 ` Yonghong Song
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