[PATCH] drm/i915: Enable fine-grained kcov instrumentation

[PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Chris Wilson]

In the next merge, we can build support for kcov at the individual file,
or driver level. This is useful to filter out the noise when doing
coverage test, i.e. we do get edges through code outside of i915.ko.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/Kconfig.debug | 12 ++++++++++++
 drivers/gpu/drm/i915/Makefile      |  1 +
 2 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
index cee87bfd10c4..eb38270d0ecd 100644
--- a/drivers/gpu/drm/i915/Kconfig.debug
+++ b/drivers/gpu/drm/i915/Kconfig.debug
@@ -42,3 +42,15 @@ config DRM_I915_DEBUG_GEM
 
           If in doubt, say "N".
 
+config DRM_I915_KCOV
+	bool "Generate fine-grained code coverage (for kcov)"
+	default n
+	select KCOV
+	help
+	  Enable instrumentation of i915.ko to generate coverage via kcov
+	  (/sys/kernel/debug/kcov). This allows coverage driven fuzzing,
+	  such as AFL, to be used and focused on the driver.
+
+	  Recommended for driver developers only.
+
+	  If in doubt, say "N".
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 0afe7b3cad07..2f4bbaca5b60 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -3,6 +3,7 @@
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
 subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
+subdir-ccflags-$(CONFIG_DRM_I915_KCOV) := $(CFLAGS_KCOV)
 subdir-ccflags-y += \
 	$(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)
 
-- 
2.8.1

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✗ Ro.CI.BAT: failure for drm/i915: Enable fine-grained kcov instrumentation

[Patchwork]

== Series Details ==

Series: drm/i915: Enable fine-grained kcov instrumentation
URL   : https://patchwork.freedesktop.org/series/10621/
State : failure

== Summary ==

Applying: drm/i915: Enable fine-grained kcov instrumentation
fatal: sha1 information is lacking or useless (drivers/gpu/drm/i915/Makefile).
error: could not build fake ancestor
Patch failed at 0001 drm/i915: Enable fine-grained kcov instrumentation
The copy of the patch that failed is found in: .git/rebase-apply/patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Joonas Lahtinen]

On ke, 2016-08-03 at 20:38 +0100, Chris Wilson wrote:
> In the next merge, we can build support for kcov at the individual file,
> or driver level. This is useful to filter out the noise when doing
> coverage test, i.e. we do get edges through code outside of i915.ko.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

Umm, is not KCOV enabled by selecting KCOV and then instrumentation is
only disabled on select objects? "KCOV_INSTRUMENT_foo.o := n"?

> ---
>  drivers/gpu/drm/i915/Kconfig.debug | 12 ++++++++++++
>  drivers/gpu/drm/i915/Makefile      |  1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index cee87bfd10c4..eb38270d0ecd 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -42,3 +42,15 @@ config DRM_I915_DEBUG_GEM
>  
>            If in doubt, say "N".
>  
> +config DRM_I915_KCOV
> +	bool "Generate fine-grained code coverage (for kcov)"
> +	default n
> +	select KCOV
> +	help
> +	  Enable instrumentation of i915.ko to generate coverage via kcov
> +	  (/sys/kernel/debug/kcov). This allows coverage driven fuzzing,
> +	  such as AFL, to be used and focused on the driver.
> +
> +	  Recommended for driver developers only.
> +
> +	  If in doubt, say "N".
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0afe7b3cad07..2f4bbaca5b60 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -3,6 +3,7 @@
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
>  subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
> +subdir-ccflags-$(CONFIG_DRM_I915_KCOV) := $(CFLAGS_KCOV)
>  subdir-ccflags-y += \
>  	$(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Chris Wilson]

On Thu, Aug 04, 2016 at 09:12:07AM +0300, Joonas Lahtinen wrote:
> On ke, 2016-08-03 at 20:38 +0100, Chris Wilson wrote:
> > In the next merge, we can build support for kcov at the individual file,
> > or driver level. This is useful to filter out the noise when doing
> > coverage test, i.e. we do get edges through code outside of i915.ko.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> 
> Umm, is not KCOV enabled by selecting KCOV and then instrumentation is
> only disabled on select objects? "KCOV_INSTRUMENT_foo.o := n"?

commit a4691deabf284a601149a067525759939cc563b2
Author: Vegard Nossum <vegard.nossum@oracle.com>
Date:   Tue Aug 2 14:07:30 2016 -0700

    kcov: allow more fine-grained coverage instrumentation
    
    For more targeted fuzzing, it's better to disable kernel-wide
    instrumentation and instead enable it on a per-subsystem basis.  This
    follows the pattern of UBSAN and allows you to compile in the kcov
    driver without instrumenting the whole kernel.
    
    To instrument a part of the kernel, you can use either
    
        # for a single file in the current directory
        KCOV_INSTRUMENT_filename.o := y
    
    or
    
        # for all the files in the current directory (excluding subdirectories)
        KCOV_INSTRUMENT := y
    
    or
    
        # (same as above)
        ccflags-y += $(CFLAGS_KCOV)
    
    or
    
        # for all the files in the current directory (including subdirectories)
        subdir-ccflags-y += $(CFLAGS_KCOV)


The commit itself adds KCOV_INSTRUMENT_ALL config target to enable
kernel-wide coverage, with KCOV then just enabling the debug interface.
-Chris

-- 
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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Jani Nikula]

On Wed, 03 Aug 2016, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> In the next merge, we can build support for kcov at the individual file,
> or driver level. This is useful to filter out the noise when doing
> coverage test, i.e. we do get edges through code outside of i915.ko.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/Kconfig.debug | 12 ++++++++++++
>  drivers/gpu/drm/i915/Makefile      |  1 +
>  2 files changed, 13 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index cee87bfd10c4..eb38270d0ecd 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -42,3 +42,15 @@ config DRM_I915_DEBUG_GEM
>  
>            If in doubt, say "N".
>  
> +config DRM_I915_KCOV
> +	bool "Generate fine-grained code coverage (for kcov)"
> +	default n
> +	select KCOV

depends on KCOV?

BR,
Jani

> +	help
> +	  Enable instrumentation of i915.ko to generate coverage via kcov
> +	  (/sys/kernel/debug/kcov). This allows coverage driven fuzzing,
> +	  such as AFL, to be used and focused on the driver.
> +
> +	  Recommended for driver developers only.
> +
> +	  If in doubt, say "N".
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0afe7b3cad07..2f4bbaca5b60 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -3,6 +3,7 @@
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
>  subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
> +subdir-ccflags-$(CONFIG_DRM_I915_KCOV) := $(CFLAGS_KCOV)
>  subdir-ccflags-y += \
>  	$(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)

-- 
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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Joonas Lahtinen]

On to, 2016-08-04 at 07:30 +0100, Chris Wilson wrote:
> On Thu, Aug 04, 2016 at 09:12:07AM +0300, Joonas Lahtinen wrote:
> > 
> > On ke, 2016-08-03 at 20:38 +0100, Chris Wilson wrote:
> > > 
> > > In the next merge, we can build support for kcov at the individual file,
> > > or driver level. This is useful to filter out the noise when doing
> > > coverage test, i.e. we do get edges through code outside of i915.ko.
> > > 
> > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Umm, is not KCOV enabled by selecting KCOV and then instrumentation is
> > only disabled on select objects? "KCOV_INSTRUMENT_foo.o := n"?
> commit a4691deabf284a601149a067525759939cc563b2
> Author: Vegard Nossum <vegard.nossum@oracle.com>
> Date:   Tue Aug 2 14:07:30 2016 -0700
> 
>     kcov: allow more fine-grained coverage instrumentation
>     
>     For more targeted fuzzing, it's better to disable kernel-wide
>     instrumentation and instead enable it on a per-subsystem basis.  This
>     follows the pattern of UBSAN and allows you to compile in the kcov
>     driver without instrumenting the whole kernel.
>     
>     To instrument a part of the kernel, you can use either
>     
>         # for a single file in the current directory
>         KCOV_INSTRUMENT_filename.o := y
>     
>     or
>     
>         # for all the files in the current directory (excluding subdirectories)
>         KCOV_INSTRUMENT := y
>     
>     or
>     
>         # (same as above)
>         ccflags-y += $(CFLAGS_KCOV)
>     
>     or
>     
>         # for all the files in the current directory (including subdirectories)
>         subdir-ccflags-y += $(CFLAGS_KCOV)
> 
> 
> The commit itself adds KCOV_INSTRUMENT_ALL config target to enable
> kernel-wide coverage, with KCOV then just enabling the debug interface.

Could reference the patch in commit message if you especially want this
reviewed upfront. I see it could be merged after we get the commit to
our tree, too.

Regards, Joonas

> -Chris
> 
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Chris Wilson]

On Thu, Aug 04, 2016 at 02:49:17PM +0300, Joonas Lahtinen wrote:
> On to, 2016-08-04 at 07:30 +0100, Chris Wilson wrote:
> > On Thu, Aug 04, 2016 at 09:12:07AM +0300, Joonas Lahtinen wrote:
> > > 
> > > On ke, 2016-08-03 at 20:38 +0100, Chris Wilson wrote:
> > > > 
> > > > In the next merge, we can build support for kcov at the individual file,
> > > > or driver level. This is useful to filter out the noise when doing
> > > > coverage test, i.e. we do get edges through code outside of i915.ko.
> > > > 
> > > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > > Umm, is not KCOV enabled by selecting KCOV and then instrumentation is
> > > only disabled on select objects? "KCOV_INSTRUMENT_foo.o := n"?
> > commit a4691deabf284a601149a067525759939cc563b2
> > Author: Vegard Nossum <vegard.nossum@oracle.com>
> > Date:   Tue Aug 2 14:07:30 2016 -0700
> > 
> >     kcov: allow more fine-grained coverage instrumentation
> >     
> >     For more targeted fuzzing, it's better to disable kernel-wide
> >     instrumentation and instead enable it on a per-subsystem basis.  This
> >     follows the pattern of UBSAN and allows you to compile in the kcov
> >     driver without instrumenting the whole kernel.
> >     
> >     To instrument a part of the kernel, you can use either
> >     
> >         # for a single file in the current directory
> >         KCOV_INSTRUMENT_filename.o := y
> >     
> >     or
> >     
> >         # for all the files in the current directory (excluding subdirectories)
> >         KCOV_INSTRUMENT := y
> >     
> >     or
> >     
> >         # (same as above)
> >         ccflags-y += $(CFLAGS_KCOV)
> >     
> >     or
> >     
> >         # for all the files in the current directory (including subdirectories)
> >         subdir-ccflags-y += $(CFLAGS_KCOV)
> > 
> > 
> > The commit itself adds KCOV_INSTRUMENT_ALL config target to enable
> > kernel-wide coverage, with KCOV then just enabling the debug interface.
> 
> Could reference the patch in commit message if you especially want this
> reviewed upfront. I see it could be merged after we get the commit to
> our tree, too.

Not expecting anything before we get our backmerge. Just found it
interesting when going over the delta from Linus.
-Chris

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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Chris Wilson]

Quoting Chris Wilson (2016-08-03 20:38:53)
> In the next merge, we can build support for kcov at the individual file,

Since a4691deabf28 ("kcov: allow more fine-grained coverage instrumentation"),

> or driver level. This is useful to filter out the noise when doing
> coverage test, i.e. we do get edges through code outside of i915.ko.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/Kconfig.debug | 12 ++++++++++++
>  drivers/gpu/drm/i915/Makefile      |  1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index cee87bfd10c4..eb38270d0ecd 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -42,3 +42,15 @@ config DRM_I915_DEBUG_GEM
>  
>            If in doubt, say "N".
>  
> +config DRM_I915_KCOV
> +       bool "Generate fine-grained code coverage (for kcov)"
> +       default n
> +       select KCOV
> +       help
> +         Enable instrumentation of i915.ko to generate coverage via kcov
> +         (/sys/kernel/debug/kcov). This allows coverage driven fuzzing,
> +         such as AFL, to be used and focused on the driver.
> +
> +         Recommended for driver developers only.
> +
> +         If in doubt, say "N".
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0afe7b3cad07..2f4bbaca5b60 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -3,6 +3,7 @@
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
>  subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
> +subdir-ccflags-$(CONFIG_DRM_I915_KCOV) := $(CFLAGS_KCOV)
>  subdir-ccflags-y += \
>         $(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)
>  
> -- 
> 2.8.1
> 
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Re: [PATCH] drm/i915: Enable fine-grained kcov instrumentation

[Chris Wilson]

Quoting Chris Wilson (2016-08-03 20:38:53)
> In the next merge, we can build support for kcov at the individual file,
> or driver level. This is useful to filter out the noise when doing
> coverage test, i.e. we do get edges through code outside of i915.ko.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>  drivers/gpu/drm/i915/Kconfig.debug | 12 ++++++++++++
>  drivers/gpu/drm/i915/Makefile      |  1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig.debug b/drivers/gpu/drm/i915/Kconfig.debug
> index cee87bfd10c4..eb38270d0ecd 100644
> --- a/drivers/gpu/drm/i915/Kconfig.debug
> +++ b/drivers/gpu/drm/i915/Kconfig.debug
> @@ -42,3 +42,15 @@ config DRM_I915_DEBUG_GEM
>  
>            If in doubt, say "N".
>  
> +config DRM_I915_KCOV
> +       bool "Generate fine-grained code coverage (for kcov)"
> +       default n
> +       select KCOV
> +       help
> +         Enable instrumentation of i915.ko to generate coverage via kcov
> +         (/sys/kernel/debug/kcov). This allows coverage driven fuzzing,
> +         such as AFL, to be used and focused on the driver.
> +
> +         Recommended for driver developers only.
> +
> +         If in doubt, say "N".
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 0afe7b3cad07..2f4bbaca5b60 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -3,6 +3,7 @@
>  # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
>  
>  subdir-ccflags-$(CONFIG_DRM_I915_WERROR) := -Werror
> +subdir-ccflags-$(CONFIG_DRM_I915_KCOV) := $(CFLAGS_KCOV)

s/:=/+=/

>  subdir-ccflags-y += \
>         $(call as-instr,movntdqa (%eax)$(comma)%xmm0,-DCONFIG_AS_MOVNTDQA)
>  
> -- 
> 2.8.1
> 
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