* [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
@ 2019-07-03 20:51 Stanislav Fomichev
2019-07-03 23:39 ` Y Song
0 siblings, 1 reply; 6+ messages in thread
From: Stanislav Fomichev @ 2019-07-03 20:51 UTC (permalink / raw)
To: netdev, bpf; +Cc: davem, ast, daniel, Stanislav Fomichev
Take the first x bytes of pt_regs for scalability tests, there is
no real reason we need x86 specific rax.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
3 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
index dea395af9ea9..d530c61d2517 100644
--- a/tools/testing/selftests/bpf/progs/loop1.c
+++ b/tools/testing/selftests/bpf/progs/loop1.c
@@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
int nested_loops(volatile struct pt_regs* ctx)
{
int i, j, sum = 0, m;
+ volatile int *any_reg = (volatile int *)ctx;
for (j = 0; j < 300; j++)
for (i = 0; i < j; i++) {
if (j & 1)
- m = ctx->rax;
+ m = *any_reg;
else
m = j;
sum += i * m;
diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
index 0637bd8e8bcf..91bb89d901e3 100644
--- a/tools/testing/selftests/bpf/progs/loop2.c
+++ b/tools/testing/selftests/bpf/progs/loop2.c
@@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
int while_true(volatile struct pt_regs* ctx)
{
int i = 0;
+ volatile int *any_reg = (volatile int *)ctx;
while (true) {
- if (ctx->rax & 1)
+ if (*any_reg & 1)
i += 3;
else
i += 7;
diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
index 30a0f6cba080..3a7f12d7186c 100644
--- a/tools/testing/selftests/bpf/progs/loop3.c
+++ b/tools/testing/selftests/bpf/progs/loop3.c
@@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
int while_true(volatile struct pt_regs* ctx)
{
__u64 i = 0, sum = 0;
+ volatile __u64 *any_reg = (volatile __u64 *)ctx;
do {
i++;
- sum += ctx->rax;
+ sum += *any_reg;
} while (i < 0x100000000ULL);
return sum;
}
--
2.22.0.410.gd8fdbe21b5-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
2019-07-03 20:51 [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent Stanislav Fomichev
@ 2019-07-03 23:39 ` Y Song
2019-07-08 16:13 ` Stanislav Fomichev
0 siblings, 1 reply; 6+ messages in thread
From: Y Song @ 2019-07-03 23:39 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: netdev, bpf, David Miller, Alexei Starovoitov, Daniel Borkmann,
Ilya Leoshkevich
On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev <sdf@google.com> wrote:
>
> Take the first x bytes of pt_regs for scalability tests, there is
> no real reason we need x86 specific rax.
>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> ---
> tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
> tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
> tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
> 3 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
> index dea395af9ea9..d530c61d2517 100644
> --- a/tools/testing/selftests/bpf/progs/loop1.c
> +++ b/tools/testing/selftests/bpf/progs/loop1.c
> @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
> int nested_loops(volatile struct pt_regs* ctx)
> {
> int i, j, sum = 0, m;
> + volatile int *any_reg = (volatile int *)ctx;
>
> for (j = 0; j < 300; j++)
> for (i = 0; i < j; i++) {
> if (j & 1)
> - m = ctx->rax;
> + m = *any_reg;
I agree. ctx->rax here is only to generate some operations, which
cannot be optimized away by the compiler. dereferencing a volatile
pointee may just serve that purpose.
Comparing the byte code generated with ctx->rax and *any_reg, they are
slightly different. Using *any_reg is slighly worse, but this should
be still okay for the test.
> else
> m = j;
> sum += i * m;
> diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
> index 0637bd8e8bcf..91bb89d901e3 100644
> --- a/tools/testing/selftests/bpf/progs/loop2.c
> +++ b/tools/testing/selftests/bpf/progs/loop2.c
> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> int while_true(volatile struct pt_regs* ctx)
> {
> int i = 0;
> + volatile int *any_reg = (volatile int *)ctx;
>
> while (true) {
> - if (ctx->rax & 1)
> + if (*any_reg & 1)
> i += 3;
> else
> i += 7;
> diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
> index 30a0f6cba080..3a7f12d7186c 100644
> --- a/tools/testing/selftests/bpf/progs/loop3.c
> +++ b/tools/testing/selftests/bpf/progs/loop3.c
> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> int while_true(volatile struct pt_regs* ctx)
> {
> __u64 i = 0, sum = 0;
> + volatile __u64 *any_reg = (volatile __u64 *)ctx;
> do {
> i++;
> - sum += ctx->rax;
> + sum += *any_reg;
> } while (i < 0x100000000ULL);
> return sum;
> }
> --
> 2.22.0.410.gd8fdbe21b5-goog
Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set
trying to solve this problem by introducing s360 arch register access
macros. I guess for now that patch set is not needed any more?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
2019-07-03 23:39 ` Y Song
@ 2019-07-08 16:13 ` Stanislav Fomichev
2019-07-08 20:14 ` Ilya Leoshkevich
0 siblings, 1 reply; 6+ messages in thread
From: Stanislav Fomichev @ 2019-07-08 16:13 UTC (permalink / raw)
To: Y Song
Cc: Stanislav Fomichev, netdev, bpf, David Miller,
Alexei Starovoitov, Daniel Borkmann, Ilya Leoshkevich
On 07/03, Y Song wrote:
> On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev <sdf@google.com> wrote:
> >
> > Take the first x bytes of pt_regs for scalability tests, there is
> > no real reason we need x86 specific rax.
> >
> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> > ---
> > tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
> > tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
> > tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
> > 3 files changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
> > index dea395af9ea9..d530c61d2517 100644
> > --- a/tools/testing/selftests/bpf/progs/loop1.c
> > +++ b/tools/testing/selftests/bpf/progs/loop1.c
> > @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
> > int nested_loops(volatile struct pt_regs* ctx)
> > {
> > int i, j, sum = 0, m;
> > + volatile int *any_reg = (volatile int *)ctx;
> >
> > for (j = 0; j < 300; j++)
> > for (i = 0; i < j; i++) {
> > if (j & 1)
> > - m = ctx->rax;
> > + m = *any_reg;
>
> I agree. ctx->rax here is only to generate some operations, which
> cannot be optimized away by the compiler. dereferencing a volatile
> pointee may just serve that purpose.
>
> Comparing the byte code generated with ctx->rax and *any_reg, they are
> slightly different. Using *any_reg is slighly worse, but this should
> be still okay for the test.
>
> > else
> > m = j;
> > sum += i * m;
> > diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
> > index 0637bd8e8bcf..91bb89d901e3 100644
> > --- a/tools/testing/selftests/bpf/progs/loop2.c
> > +++ b/tools/testing/selftests/bpf/progs/loop2.c
> > @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> > int while_true(volatile struct pt_regs* ctx)
> > {
> > int i = 0;
> > + volatile int *any_reg = (volatile int *)ctx;
> >
> > while (true) {
> > - if (ctx->rax & 1)
> > + if (*any_reg & 1)
> > i += 3;
> > else
> > i += 7;
> > diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
> > index 30a0f6cba080..3a7f12d7186c 100644
> > --- a/tools/testing/selftests/bpf/progs/loop3.c
> > +++ b/tools/testing/selftests/bpf/progs/loop3.c
> > @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> > int while_true(volatile struct pt_regs* ctx)
> > {
> > __u64 i = 0, sum = 0;
> > + volatile __u64 *any_reg = (volatile __u64 *)ctx;
> > do {
> > i++;
> > - sum += ctx->rax;
> > + sum += *any_reg;
> > } while (i < 0x100000000ULL);
> > return sum;
> > }
> > --
> > 2.22.0.410.gd8fdbe21b5-goog
>
> Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set
> trying to solve this problem by introducing s360 arch register access
> macros. I guess for now that patch set is not needed any more?
Oh, I missed them. Do they fix the tests for other (non-s360) arches as
well? I was trying to fix the issue by not depending on any arch
specific stuff because the test really doesn't care :-)
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
2019-07-08 16:13 ` Stanislav Fomichev
@ 2019-07-08 20:14 ` Ilya Leoshkevich
2019-07-08 21:20 ` Stanislav Fomichev
0 siblings, 1 reply; 6+ messages in thread
From: Ilya Leoshkevich @ 2019-07-08 20:14 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: Y Song, Stanislav Fomichev, netdev, bpf, David Miller,
Alexei Starovoitov, Daniel Borkmann
> Am 08.07.2019 um 18:13 schrieb Stanislav Fomichev <sdf@fomichev.me>:
>
> On 07/03, Y Song wrote:
>> On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev <sdf@google.com> wrote:
>>>
>>> Take the first x bytes of pt_regs for scalability tests, there is
>>> no real reason we need x86 specific rax.
>>>
>>> Signed-off-by: Stanislav Fomichev <sdf@google.com>
>>> ---
>>> tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
>>> tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
>>> tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
>>> 3 files changed, 6 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
>>> index dea395af9ea9..d530c61d2517 100644
>>> --- a/tools/testing/selftests/bpf/progs/loop1.c
>>> +++ b/tools/testing/selftests/bpf/progs/loop1.c
>>> @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
>>> int nested_loops(volatile struct pt_regs* ctx)
>>> {
>>> int i, j, sum = 0, m;
>>> + volatile int *any_reg = (volatile int *)ctx;
>>>
>>> for (j = 0; j < 300; j++)
>>> for (i = 0; i < j; i++) {
>>> if (j & 1)
>>> - m = ctx->rax;
>>> + m = *any_reg;
>>
>> I agree. ctx->rax here is only to generate some operations, which
>> cannot be optimized away by the compiler. dereferencing a volatile
>> pointee may just serve that purpose.
>>
>> Comparing the byte code generated with ctx->rax and *any_reg, they are
>> slightly different. Using *any_reg is slighly worse, but this should
>> be still okay for the test.
>>
>>> else
>>> m = j;
>>> sum += i * m;
>>> diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
>>> index 0637bd8e8bcf..91bb89d901e3 100644
>>> --- a/tools/testing/selftests/bpf/progs/loop2.c
>>> +++ b/tools/testing/selftests/bpf/progs/loop2.c
>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
>>> int while_true(volatile struct pt_regs* ctx)
>>> {
>>> int i = 0;
>>> + volatile int *any_reg = (volatile int *)ctx;
>>>
>>> while (true) {
>>> - if (ctx->rax & 1)
>>> + if (*any_reg & 1)
>>> i += 3;
>>> else
>>> i += 7;
>>> diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
>>> index 30a0f6cba080..3a7f12d7186c 100644
>>> --- a/tools/testing/selftests/bpf/progs/loop3.c
>>> +++ b/tools/testing/selftests/bpf/progs/loop3.c
>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
>>> int while_true(volatile struct pt_regs* ctx)
>>> {
>>> __u64 i = 0, sum = 0;
>>> + volatile __u64 *any_reg = (volatile __u64 *)ctx;
>>> do {
>>> i++;
>>> - sum += ctx->rax;
>>> + sum += *any_reg;
>>> } while (i < 0x100000000ULL);
>>> return sum;
>>> }
>>> --
>>> 2.22.0.410.gd8fdbe21b5-goog
>>
>> Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set
>> trying to solve this problem by introducing s360 arch register access
>> macros. I guess for now that patch set is not needed any more?
> Oh, I missed them. Do they fix the tests for other (non-s360) arches as
> well? I was trying to fix the issue by not depending on any arch
> specific stuff because the test really doesn't care :-)
They are supposed to work for everything that defines PT_REGS_RC in
bpf_helpers.h, but I have to admit I tested only x86_64 and s390.
The main source of problems with my approach were mismatching definitions
of struct pt_regs for userspace and kernel, and because of that there was
some tweaking required for both arches. I will double check how it looks
for others (arm, mips, ppc, sparc) tomorrow.
Best regards,
Ilya
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
2019-07-08 20:14 ` Ilya Leoshkevich
@ 2019-07-08 21:20 ` Stanislav Fomichev
2019-07-08 21:44 ` Ilya Leoshkevich
0 siblings, 1 reply; 6+ messages in thread
From: Stanislav Fomichev @ 2019-07-08 21:20 UTC (permalink / raw)
To: Ilya Leoshkevich
Cc: Y Song, Stanislav Fomichev, netdev, bpf, David Miller,
Alexei Starovoitov, Daniel Borkmann
On 07/08, Ilya Leoshkevich wrote:
>
>
> > Am 08.07.2019 um 18:13 schrieb Stanislav Fomichev <sdf@fomichev.me>:
> >
> > On 07/03, Y Song wrote:
> >> On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev <sdf@google.com> wrote:
> >>>
> >>> Take the first x bytes of pt_regs for scalability tests, there is
> >>> no real reason we need x86 specific rax.
> >>>
> >>> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> >>> ---
> >>> tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
> >>> tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
> >>> tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
> >>> 3 files changed, 6 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
> >>> index dea395af9ea9..d530c61d2517 100644
> >>> --- a/tools/testing/selftests/bpf/progs/loop1.c
> >>> +++ b/tools/testing/selftests/bpf/progs/loop1.c
> >>> @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
> >>> int nested_loops(volatile struct pt_regs* ctx)
> >>> {
> >>> int i, j, sum = 0, m;
> >>> + volatile int *any_reg = (volatile int *)ctx;
> >>>
> >>> for (j = 0; j < 300; j++)
> >>> for (i = 0; i < j; i++) {
> >>> if (j & 1)
> >>> - m = ctx->rax;
> >>> + m = *any_reg;
> >>
> >> I agree. ctx->rax here is only to generate some operations, which
> >> cannot be optimized away by the compiler. dereferencing a volatile
> >> pointee may just serve that purpose.
> >>
> >> Comparing the byte code generated with ctx->rax and *any_reg, they are
> >> slightly different. Using *any_reg is slighly worse, but this should
> >> be still okay for the test.
> >>
> >>> else
> >>> m = j;
> >>> sum += i * m;
> >>> diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
> >>> index 0637bd8e8bcf..91bb89d901e3 100644
> >>> --- a/tools/testing/selftests/bpf/progs/loop2.c
> >>> +++ b/tools/testing/selftests/bpf/progs/loop2.c
> >>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> >>> int while_true(volatile struct pt_regs* ctx)
> >>> {
> >>> int i = 0;
> >>> + volatile int *any_reg = (volatile int *)ctx;
> >>>
> >>> while (true) {
> >>> - if (ctx->rax & 1)
> >>> + if (*any_reg & 1)
> >>> i += 3;
> >>> else
> >>> i += 7;
> >>> diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
> >>> index 30a0f6cba080..3a7f12d7186c 100644
> >>> --- a/tools/testing/selftests/bpf/progs/loop3.c
> >>> +++ b/tools/testing/selftests/bpf/progs/loop3.c
> >>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
> >>> int while_true(volatile struct pt_regs* ctx)
> >>> {
> >>> __u64 i = 0, sum = 0;
> >>> + volatile __u64 *any_reg = (volatile __u64 *)ctx;
> >>> do {
> >>> i++;
> >>> - sum += ctx->rax;
> >>> + sum += *any_reg;
> >>> } while (i < 0x100000000ULL);
> >>> return sum;
> >>> }
> >>> --
> >>> 2.22.0.410.gd8fdbe21b5-goog
> >>
> >> Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set
> >> trying to solve this problem by introducing s360 arch register access
> >> macros. I guess for now that patch set is not needed any more?
> > Oh, I missed them. Do they fix the tests for other (non-s360) arches as
> > well? I was trying to fix the issue by not depending on any arch
> > specific stuff because the test really doesn't care :-)
>
> They are supposed to work for everything that defines PT_REGS_RC in
> bpf_helpers.h, but I have to admit I tested only x86_64 and s390.
>
> The main source of problems with my approach were mismatching definitions
> of struct pt_regs for userspace and kernel, and because of that there was
> some tweaking required for both arches. I will double check how it looks
> for others (arm, mips, ppc, sparc) tomorrow.
Thanks, I've tested your patches and they fix my issue as well. So you
can have my Tested-by if we'd go with your approach.
One thing I don't understand is: why do you add 'ifdef __KERNEL__' to
the bpf_helpers.h for x86 case? Who is using bpf_helpers.h with
__KERNEL__ defined? Is it perf?
> Best regards,
> Ilya
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent
2019-07-08 21:20 ` Stanislav Fomichev
@ 2019-07-08 21:44 ` Ilya Leoshkevich
0 siblings, 0 replies; 6+ messages in thread
From: Ilya Leoshkevich @ 2019-07-08 21:44 UTC (permalink / raw)
To: Stanislav Fomichev
Cc: Y Song, Stanislav Fomichev, netdev, bpf, David Miller,
Alexei Starovoitov, Daniel Borkmann
> Am 08.07.2019 um 23:20 schrieb Stanislav Fomichev <sdf@fomichev.me>:
>
> On 07/08, Ilya Leoshkevich wrote:
>>
>>
>>> Am 08.07.2019 um 18:13 schrieb Stanislav Fomichev <sdf@fomichev.me>:
>>>
>>> On 07/03, Y Song wrote:
>>>> On Wed, Jul 3, 2019 at 1:51 PM Stanislav Fomichev <sdf@google.com> wrote:
>>>>>
>>>>> Take the first x bytes of pt_regs for scalability tests, there is
>>>>> no real reason we need x86 specific rax.
>>>>>
>>>>> Signed-off-by: Stanislav Fomichev <sdf@google.com>
>>>>> ---
>>>>> tools/testing/selftests/bpf/progs/loop1.c | 3 ++-
>>>>> tools/testing/selftests/bpf/progs/loop2.c | 3 ++-
>>>>> tools/testing/selftests/bpf/progs/loop3.c | 3 ++-
>>>>> 3 files changed, 6 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/bpf/progs/loop1.c b/tools/testing/selftests/bpf/progs/loop1.c
>>>>> index dea395af9ea9..d530c61d2517 100644
>>>>> --- a/tools/testing/selftests/bpf/progs/loop1.c
>>>>> +++ b/tools/testing/selftests/bpf/progs/loop1.c
>>>>> @@ -14,11 +14,12 @@ SEC("raw_tracepoint/kfree_skb")
>>>>> int nested_loops(volatile struct pt_regs* ctx)
>>>>> {
>>>>> int i, j, sum = 0, m;
>>>>> + volatile int *any_reg = (volatile int *)ctx;
>>>>>
>>>>> for (j = 0; j < 300; j++)
>>>>> for (i = 0; i < j; i++) {
>>>>> if (j & 1)
>>>>> - m = ctx->rax;
>>>>> + m = *any_reg;
>>>>
>>>> I agree. ctx->rax here is only to generate some operations, which
>>>> cannot be optimized away by the compiler. dereferencing a volatile
>>>> pointee may just serve that purpose.
>>>>
>>>> Comparing the byte code generated with ctx->rax and *any_reg, they are
>>>> slightly different. Using *any_reg is slighly worse, but this should
>>>> be still okay for the test.
>>>>
>>>>> else
>>>>> m = j;
>>>>> sum += i * m;
>>>>> diff --git a/tools/testing/selftests/bpf/progs/loop2.c b/tools/testing/selftests/bpf/progs/loop2.c
>>>>> index 0637bd8e8bcf..91bb89d901e3 100644
>>>>> --- a/tools/testing/selftests/bpf/progs/loop2.c
>>>>> +++ b/tools/testing/selftests/bpf/progs/loop2.c
>>>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
>>>>> int while_true(volatile struct pt_regs* ctx)
>>>>> {
>>>>> int i = 0;
>>>>> + volatile int *any_reg = (volatile int *)ctx;
>>>>>
>>>>> while (true) {
>>>>> - if (ctx->rax & 1)
>>>>> + if (*any_reg & 1)
>>>>> i += 3;
>>>>> else
>>>>> i += 7;
>>>>> diff --git a/tools/testing/selftests/bpf/progs/loop3.c b/tools/testing/selftests/bpf/progs/loop3.c
>>>>> index 30a0f6cba080..3a7f12d7186c 100644
>>>>> --- a/tools/testing/selftests/bpf/progs/loop3.c
>>>>> +++ b/tools/testing/selftests/bpf/progs/loop3.c
>>>>> @@ -14,9 +14,10 @@ SEC("raw_tracepoint/consume_skb")
>>>>> int while_true(volatile struct pt_regs* ctx)
>>>>> {
>>>>> __u64 i = 0, sum = 0;
>>>>> + volatile __u64 *any_reg = (volatile __u64 *)ctx;
>>>>> do {
>>>>> i++;
>>>>> - sum += ctx->rax;
>>>>> + sum += *any_reg;
>>>>> } while (i < 0x100000000ULL);
>>>>> return sum;
>>>>> }
>>>>> --
>>>>> 2.22.0.410.gd8fdbe21b5-goog
>>>>
>>>> Ilya Leoshkevich (iii@linux.ibm.com, cc'ed) has another patch set
>>>> trying to solve this problem by introducing s360 arch register access
>>>> macros. I guess for now that patch set is not needed any more?
>>> Oh, I missed them. Do they fix the tests for other (non-s360) arches as
>>> well? I was trying to fix the issue by not depending on any arch
>>> specific stuff because the test really doesn't care :-)
>>
>> They are supposed to work for everything that defines PT_REGS_RC in
>> bpf_helpers.h, but I have to admit I tested only x86_64 and s390.
>>
>> The main source of problems with my approach were mismatching definitions
>> of struct pt_regs for userspace and kernel, and because of that there was
>> some tweaking required for both arches. I will double check how it looks
>> for others (arm, mips, ppc, sparc) tomorrow.
> Thanks, I've tested your patches and they fix my issue as well. So you
> can have my Tested-by if we'd go with your approach.
>
> One thing I don't understand is: why do you add 'ifdef __KERNEL__' to
> the bpf_helpers.h for x86 case? Who is using bpf_helpers.h with
> __KERNEL__ defined? Is it perf?
That’s samples/bpf. Also, there is a modified copy of it in bcc
(src/cc/export/helpers.h), which also gets built with __KERNEL__.
Best regards,
Ilya
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-07-08 21:44 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-03 20:51 [PATCH bpf-next] selftests/bpf: make verifier loop tests arch independent Stanislav Fomichev
2019-07-03 23:39 ` Y Song
2019-07-08 16:13 ` Stanislav Fomichev
2019-07-08 20:14 ` Ilya Leoshkevich
2019-07-08 21:20 ` Stanislav Fomichev
2019-07-08 21:44 ` Ilya Leoshkevich
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