Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64

From	James Morse <james.morse@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64
Date	2016-06-16 12:50 +0200
Message-ID	<rKD22-7fn-19@gated-at.bofh.it> (permalink)
References	(2 earlier) <rK16q-8sH-13@gated-at.bofh.it> <rKfj3-Ig-3@gated-at.bofh.it> <rKhux-21f-11@gated-at.bofh.it> <rKhEe-24C-9@gated-at.bofh.it> <rKjZo-3Eh-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On 15/06/16 15:25, Mark Rutland wrote:
> On Wed, Jun 15, 2016 at 01:53:03PM +0200, Alexander Potapenko wrote:
>> On Wed, Jun 15, 2016 at 1:44 PM, Mark Rutland <mark.rutland@arm.com> wrote:
>>> On Wed, Jun 15, 2016 at 10:25:10AM +0100, Mark Rutland wrote:
>>>> On Tue, Jun 14, 2016 at 08:16:08PM +0200, Alexander Potapenko wrote:
>>>>> On Tue, Jun 14, 2016 at 7:55 PM, Mark Rutland <mark.rutland@arm.com> wrote:
>>>>>> I built and booted (via EFI) a kernel with this feature enabled (also
>>>>>> with the boot/Makefile change removed). I haven't tested the feature
>>>>>> itself as such, as I'm not sure how to do that.
>>>>> You can test it by running the test program from Documentation/kcov.txt.
>>>>
>>>> Ah, I hadn't spotted that. If I get the chance I'll try to give that a
>>>> go.
>>>
>>> I just had a go (with this applied atop of v4.7-rc3), and I get:
>>>
>>> root@ribbensteg:/home/nanook# ./kcov
>>> mmap: No such device
>>>
>>> The device exists (it was able to open the fd, evidently):
>>>
>>> root@ribbensteg:/home/nanook# ls -al /sys/kernel/debug/kcov
>>> -rw------- 1 root root 0 Jan  1  1970 /sys/kernel/debug/kcov
>>>
>>> Strace show me:
>>>
>>> openat(AT_FDCWD, "/sys/kernel/debug/kcov", O_RDWR) = 3
>>> ioctl(3, CHIOMOVE or CM_IOCGATR, 0x10000) = 0
>>> mmap(NULL, 524288, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = -1 ENODEV (No such device)
>>>
>>> It doesn't look like the error paths in kcov_mmap are hitting.
>>>
>>> Any ideas?
>> According to Dmitry (thanks, Dmitry!) this has regressed recently, but
>> there's a pending patch that should probably fix the problem:
>> http://lkml.iu.edu/hypermail/linux/kernel/1605.2/04379.html
> 
> Thanks for the pointer! With that applied, the program runs.
> 
> However, it looks like I missed a warning from the kernel build system, 
> and my toolchain doesn't actually support -fsanitize-coverage=trace-pc,
> so I'm not going to be able to test that further.

I dusted off a compiler that supports this, and ran the sample program under
Documentation with the above unproxify patch.

Tested-by: James Morse <james.morse@arm.com>


Thanks,

James

Thread

[PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-14 19:00 +0200
  Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-14 19:20 +0200
  Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-14 20:00 +0200
    Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-14 20:20 +0200
      Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-15 11:30 +0200
        Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-15 13:50 +0200
          Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-15 14:00 +0200
            Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-15 16:30 +0200
              Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Dmitry Vyukov <dvyukov@google.com> - 2016-06-15 16:40 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-15 17:10 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Dmitry Vyukov <dvyukov@google.com> - 2016-06-15 17:30 +0200
              Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 James Morse <james.morse@arm.com> - 2016-06-16 12:50 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-16 17:30 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-16 17:50 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2016-06-16 18:30 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Catalin Marinas <catalin.marinas@arm.com> - 2016-06-16 18:40 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Alexander Potapenko <glider@google.com> - 2016-06-16 18:40 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 James Morse <james.morse@arm.com> - 2016-06-16 18:40 +0200
                Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64 Mark Rutland <mark.rutland@arm.com> - 2016-06-16 18:40 +0200

csiph-web