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

From	Mark Rutland <mark.rutland@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2] arm64: allow building with kcov coverage on ARM64
Date	2016-06-15 13:50 +0200
Message-ID	<rKhux-21f-11@gated-at.bofh.it> (permalink)
References	<rJZQZ-7rp-5@gated-at.bofh.it> <rK0N3-865-7@gated-at.bofh.it> <rK16q-8sH-13@gated-at.bofh.it> <rKfj3-Ig-3@gated-at.bofh.it>
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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?

Thanks,
Mark.

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

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