Two new functions in bpf contain a cast from a 'u64' to a
pointer. This works on 64-bit architectures but causes a warning
on all 32-bit architectures:
kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp':
kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
u64 ctx = *(long *)r1;
This changes the cast to first convert the u64 argument into a uintptr_t,
which is guaranteed to be the same size as a pointer.
Signed-off-by: Arnd Bergmann <[email protected]>
Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs")
---
kernel/trace/bpf_trace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 413ec5614180..c082313a523a 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -347,7 +347,7 @@ static u64 bpf_perf_event_output_tp(u64 r1, u64 r2, u64 index, u64 r4, u64 size)
* from bpf program and contain a pointer to 'struct pt_regs'. Fetch it
* from there and call the same bpf_perf_event_output() helper
*/
- u64 ctx = *(long *)r1;
+ u64 ctx = *(long *)(uintptr_t)r1;
return bpf_perf_event_output(ctx, r2, index, r4, size);
}
@@ -365,7 +365,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_tp = {
static u64 bpf_get_stackid_tp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
- u64 ctx = *(long *)r1;
+ u64 ctx = *(long *)(uintptr_t)r1;
return bpf_get_stackid(ctx, r2, r3, r4, r5);
}
--
2.7.0
On Sat, Apr 16, 2016 at 10:29:33PM +0200, Arnd Bergmann wrote:
> Two new functions in bpf contain a cast from a 'u64' to a
> pointer. This works on 64-bit architectures but causes a warning
> on all 32-bit architectures:
>
> kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp':
> kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> u64 ctx = *(long *)r1;
>
> This changes the cast to first convert the u64 argument into a uintptr_t,
> which is guaranteed to be the same size as a pointer.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs")
Thanks.
Acked-by: Alexei Starovoitov <[email protected]>
I guess I started to rely on 0-day build-bot too much.
This patch has been in my tree for 2+ weeks and then in net-next and
I didn't receive a single email from build-bot about this warning,
though I do receive them for my other work-in-progress stuff. Odd.
Fengguang, any idea why build-bot sometimes silent?
From: Arnd Bergmann <[email protected]>
Date: Sat, 16 Apr 2016 22:29:33 +0200
> Two new functions in bpf contain a cast from a 'u64' to a
> pointer. This works on 64-bit architectures but causes a warning
> on all 32-bit architectures:
>
> kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp':
> kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> u64 ctx = *(long *)r1;
>
> This changes the cast to first convert the u64 argument into a uintptr_t,
> which is guaranteed to be the same size as a pointer.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
> Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs")
Applied.
Hi Alexei,
On Sat, Apr 16, 2016 at 05:47:42PM -0700, Alexei Starovoitov wrote:
> On Sat, Apr 16, 2016 at 10:29:33PM +0200, Arnd Bergmann wrote:
> > Two new functions in bpf contain a cast from a 'u64' to a
> > pointer. This works on 64-bit architectures but causes a warning
> > on all 32-bit architectures:
> >
> > kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp':
> > kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> > u64 ctx = *(long *)r1;
> >
> > This changes the cast to first convert the u64 argument into a uintptr_t,
> > which is guaranteed to be the same size as a pointer.
> >
> > Signed-off-by: Arnd Bergmann <[email protected]>
> > Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs")
>
> Thanks.
> Acked-by: Alexei Starovoitov <[email protected]>
>
> I guess I started to rely on 0-day build-bot too much.
> This patch has been in my tree for 2+ weeks and then in net-next and
> I didn't receive a single email from build-bot about this warning,
> though I do receive them for my other work-in-progress stuff. Odd.
> Fengguang, any idea why build-bot sometimes silent?
Sorry I went off for some time.. Philip, would you help have a check?
Thanks,
Fengguang
On Tue, Apr 19, 2016 at 10:33:34AM +0800, Fengguang Wu wrote:
> Hi Alexei,
>
> On Sat, Apr 16, 2016 at 05:47:42PM -0700, Alexei Starovoitov wrote:
> > On Sat, Apr 16, 2016 at 10:29:33PM +0200, Arnd Bergmann wrote:
> > > Two new functions in bpf contain a cast from a 'u64' to a
> > > pointer. This works on 64-bit architectures but causes a warning
> > > on all 32-bit architectures:
> > >
> > > kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp':
> > > kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> > > u64 ctx = *(long *)r1;
> > >
> > > This changes the cast to first convert the u64 argument into a uintptr_t,
> > > which is guaranteed to be the same size as a pointer.
> > >
> > > Signed-off-by: Arnd Bergmann <[email protected]>
> > > Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs")
> >
> > Thanks.
> > Acked-by: Alexei Starovoitov <[email protected]>
> >
> > I guess I started to rely on 0-day build-bot too much.
> > This patch has been in my tree for 2+ weeks and then in net-next and
> > I didn't receive a single email from build-bot about this warning,
> > though I do receive them for my other work-in-progress stuff. Odd.
> > Fengguang, any idea why build-bot sometimes silent?
>
> Sorry I went off for some time.. Philip, would you help have a check?
Hi Alexei, i have done some investigation for this. Fengguang, pls correct me if my understanding is wrong.
0day has caught the warning for f1ff54 commit around 2016-3-22, which considers the same warning in future is not new one, thus neglect it.
rli9@inn /kbuild-tests/build-error$ cat kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size
kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
2016-03-22 17:12:38 xian bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612 f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec
And for f1ff54's warning, 0day actually bisects to it, but then it checks the head of bpf/master at that time which is 321e70e, find the error is not existed, so
it ignores the interim warning to not send email report.
2016-03-22_17:15:49 O: R: /kbuild/src/consumer/kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error # 0 errors
2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error/ # 0 errors
2016-03-22_17:15:49 O: /c/kernel-tests/list-head bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612
2016-03-22_17:16:03 O: .
2016-03-22_17:16:03 O: ..
2016-03-22_17:16:03 O: kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size
2016-03-22_17:16:03 O: 2016-03-22 17:16:03 don't email interim warnings
2016-03-22_17:16:03 O: 2016-03-22 17:16:03 error no longer exist in head bpf/master 321e70e79c94e5e6394a882d567baac949b74000, check
/tmp/kernel/i386-randconfig-x009-201612/gcc-5/321e70e79c94e5e6394a882d567baac949b74000, errno 14
2016-03-22_17:16:03 O: 2016-03-22 17:16:03 Don't email interim warnings!
what really happens to 321e70e is it has build error (i rerun it to confirm), which is reported at https://lists.01.org/pipermail/kbuild-all/2016-March/018625.html. So this is
a possible change to be done in 0day to report the first bad commit when HEAD is build error.
2016-04-19_15:00:39 O: 2016-04-19 15:00 Running /kbuild-tests/build-queue/lkp-nex06-consumer/i386-randconfig-x009-201612-gcc-5-321e70e79c94e5e6394a882d567baac949b74000
2016-04-19_15:00:39 O: create new KBUILD_OUTPUT dir /kbuild/obj/consumer/i386-randconfig-x009-201612
2016-04-19_15:00:39 O: git checkout -B build-queue 321e70e79c94e5e6394a882d567baac949b74000
2016-04-19_15:07:08 E: 330 real 4732 user 629 sys 1620.50% cpu i386-randconfig-x009-201612
2016-04-19_15:07:13 O: status: FAIL: build error
2016-04-19_15:07:13 O: ERROR: "tcp_sendpage" [drivers/staging/lustre/lnet/klnds/socklnd/ksocklnd.ko] undefined!
>
> Thanks,
> Fengguang
On 4/19/16 3:09 AM, Philip Li wrote:
> On Tue, Apr 19, 2016 at 10:33:34AM +0800, Fengguang Wu wrote:
>>> Fengguang, any idea why build-bot sometimes silent?
>>
>> Sorry I went off for some time.. Philip, would you help have a check?
> Hi Alexei, i have done some investigation for this. Fengguang, pls correct me if my understanding is wrong.
>
> 0day has caught the warning for f1ff54 commit around 2016-3-22, which considers the same warning in future is not new one, thus neglect it.
>
> rli9@inn /kbuild-tests/build-error$ cat kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size
> kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
>
> 2016-03-22 17:12:38 xian bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612 f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec
>
> And for f1ff54's warning, 0day actually bisects to it, but then it checks the head of bpf/master at that time which is 321e70e, find the error is not existed, so
> it ignores the interim warning to not send email report.
>
> 2016-03-22_17:15:49 O: R: /kbuild/src/consumer/kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
> 2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error # 0 errors
> 2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error/ # 0 errors
> 2016-03-22_17:15:49 O: /c/kernel-tests/list-head bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612
> 2016-03-22_17:16:03 O: .
> 2016-03-22_17:16:03 O: ..
> 2016-03-22_17:16:03 O: kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size
> 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 don't email interim warnings
> 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 error no longer exist in head bpf/master 321e70e79c94e5e6394a882d567baac949b74000, check
> /tmp/kernel/i386-randconfig-x009-201612/gcc-5/321e70e79c94e5e6394a882d567baac949b74000, errno 14
> 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 Don't email interim warnings!
>
>
> what really happens to 321e70e is it has build error (i rerun it to confirm), which is reported. So this is
> a possible change to be done in 0day to report the first bad commit when HEAD is build error.
excellent sleuthing! Sounds like the adjustment to 0day is forthcoming.
Thank you for great tool!