[PATCH v2 0/2] Fix a bunch of allmodconfig errors

[PATCH v2 0/2] Fix a bunch of allmodconfig errors

[Lee Jones]

Since b339ec9c229aa ("kbuild: Only default to -Werror if COMPILE_TEST") WERROR 
now defaults to COMPILE_TEST meaning that it's enabled for allmodconfig        
builds.  This leads to some interesting failures, each resolved in this set.   
                                                                               
With this set applied, I am able to obtain a successful allmodconfig Arm build.

v1 => v2:
 - Remove superfluous change (these two override it)
 - Mark only DRM_AMD_DC ("the new display engine) as Broken
 - Change logic to only *include* working arches, not *preclude* them

Lee Jones (2):
  drm/amdgpu: Temporarily disable broken Clang builds due to blown
    stack-frame
  Kconfig.debug: Provide a little extra FRAME_WARN leeway when KASAN is
    enabled

 drivers/gpu/drm/amd/display/Kconfig | 7 +++++++
 lib/Kconfig.debug                   | 1 +
 2 files changed, 8 insertions(+)

-- 
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[PATCH v2 1/2] drm/amdgpu: Temporarily disable broken Clang builds due to blown stack-frame

[Lee Jones]

calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
architectures built with Clang (all released versions), whereby the stack
frame gets blown up to well over 5k.  This would cause an immediate kernel
panic on most architectures.  We'll revert this when the following bug report
has been resolved: https://github.com/llvm/llvm-project/issues/41896.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee@kernel.org>
---
 drivers/gpu/drm/amd/display/Kconfig | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
index 6925e0280dbe6..f4f3d2665a6b2 100644
--- a/drivers/gpu/drm/amd/display/Kconfig
+++ b/drivers/gpu/drm/amd/display/Kconfig
@@ -5,6 +5,7 @@ menu "Display Engine Configuration"
 config DRM_AMD_DC
 	bool "AMD DC - Enable new display engine"
 	default y
+	depends on BROKEN || !CC_IS_CLANG || X86_64 || SPARC64 || ARM64
 	select SND_HDA_COMPONENT if SND_HDA_CORE
 	select DRM_AMD_DC_DCN if (X86 || PPC_LONG_DOUBLE_128)
 	help
@@ -12,6 +13,12 @@ config DRM_AMD_DC
 	  support for AMDGPU. This adds required support for Vega and
 	  Raven ASICs.
 
+	  calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
+	  architectures built with Clang (all released versions), whereby the stack
+	  frame gets blown up to well over 5k.  This would cause an immediate kernel
+	  panic on most architectures.  We'll revert this when the following bug report
+	  has been resolved: https://github.com/llvm/llvm-project/issues/41896.
+
 config DRM_AMD_DC_DCN
 	def_bool n
 	help
-- 
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Re: [PATCH v2 1/2] drm/amdgpu: Temporarily disable broken Clang builds due to blown stack-frame

[Arnd Bergmann]

On Fri, Nov 25, 2022, at 13:07, Lee Jones wrote:
> calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
> architectures built with Clang (all released versions), whereby the stack
> frame gets blown up to well over 5k.  This would cause an immediate kernel
> panic on most architectures.  We'll revert this when the following bug report
> has been resolved: https://github.com/llvm/llvm-project/issues/41896.
>
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Lee Jones <lee@kernel.org>

Acked-by: Arnd Bergmann <arnd@arndb.de>

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Re: [PATCH v2 1/2] drm/amdgpu: Temporarily disable broken Clang builds due to blown stack-frame

[Nathan Chancellor]

On Fri, Nov 25, 2022 at 12:07:49PM +0000, Lee Jones wrote:
> calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
> architectures built with Clang (all released versions), whereby the stack
> frame gets blown up to well over 5k.  This would cause an immediate kernel
> panic on most architectures.  We'll revert this when the following bug report
> has been resolved: https://github.com/llvm/llvm-project/issues/41896.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Lee Jones <lee@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/gpu/drm/amd/display/Kconfig | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
> index 6925e0280dbe6..f4f3d2665a6b2 100644
> --- a/drivers/gpu/drm/amd/display/Kconfig
> +++ b/drivers/gpu/drm/amd/display/Kconfig
> @@ -5,6 +5,7 @@ menu "Display Engine Configuration"
>  config DRM_AMD_DC
>  	bool "AMD DC - Enable new display engine"
>  	default y
> +	depends on BROKEN || !CC_IS_CLANG || X86_64 || SPARC64 || ARM64
>  	select SND_HDA_COMPONENT if SND_HDA_CORE
>  	select DRM_AMD_DC_DCN if (X86 || PPC_LONG_DOUBLE_128)
>  	help
> @@ -12,6 +13,12 @@ config DRM_AMD_DC
>  	  support for AMDGPU. This adds required support for Vega and
>  	  Raven ASICs.
>  
> +	  calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
> +	  architectures built with Clang (all released versions), whereby the stack
> +	  frame gets blown up to well over 5k.  This would cause an immediate kernel
> +	  panic on most architectures.  We'll revert this when the following bug report
> +	  has been resolved: https://github.com/llvm/llvm-project/issues/41896.
> +
>  config DRM_AMD_DC_DCN
>  	def_bool n
>  	help
> -- 
> 2.38.1.584.g0f3c55d4c2-goog
> 

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[PATCH v2 2/2] Kconfig.debug: Provide a little extra FRAME_WARN leeway when KASAN is enabled

[Lee Jones]

When enabled, KASAN enlarges function's stack-frames.  Pushing quite a
few over the current threshold.  This can mainly be seen on 32-bit
architectures where the present limit (when !GCC) is a lowly
1024-Bytes.

Signed-off-by: Lee Jones <lee@kernel.org>
---
 lib/Kconfig.debug | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c3c0b077ade33..82d475168db95 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -399,6 +399,7 @@ config FRAME_WARN
 	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
 	default 2048 if PARISC
 	default 1536 if (!64BIT && XTENSA)
+	default 1280 if KASAN && !64BIT
 	default 1024 if !64BIT
 	default 2048 if 64BIT
 	help
-- 
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Re: [PATCH v2 2/2] Kconfig.debug: Provide a little extra FRAME_WARN leeway when KASAN is enabled

[Lee Jones]

On Fri, 25 Nov 2022, Lee Jones wrote:

> When enabled, KASAN enlarges function's stack-frames.  Pushing quite a
> few over the current threshold.  This can mainly be seen on 32-bit
> architectures where the present limit (when !GCC) is a lowly
> 1024-Bytes.
> 
> Signed-off-by: Lee Jones <lee@kernel.org>
> ---
>  lib/Kconfig.debug | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index c3c0b077ade33..82d475168db95 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -399,6 +399,7 @@ config FRAME_WARN
>  	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
>  	default 2048 if PARISC
>  	default 1536 if (!64BIT && XTENSA)
> +	default 1280 if KASAN && !64BIT
>  	default 1024 if !64BIT
>  	default 2048 if 64BIT
>  	help

Note this also fixes 61 warnings when

  (GCC && !GCC_PLUGIN_LATENT_ENTROPY)

... which as Arnd says should not be enabled by default.  We'll
address that issue once this set has been applied.

-- 
Lee Jones [李琼斯]

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Re: [PATCH v2 2/2] Kconfig.debug: Provide a little extra FRAME_WARN leeway when KASAN is enabled

[Arnd Bergmann]

On Fri, Nov 25, 2022, at 14:40, Lee Jones wrote:
> On Fri, 25 Nov 2022, Lee Jones wrote:
>
>> When enabled, KASAN enlarges function's stack-frames.  Pushing quite a
>> few over the current threshold.  This can mainly be seen on 32-bit
>> architectures where the present limit (when !GCC) is a lowly
>> 1024-Bytes.
>> 
>> Signed-off-by: Lee Jones <lee@kernel.org>
>> ---
>>  lib/Kconfig.debug | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
>> index c3c0b077ade33..82d475168db95 100644
>> --- a/lib/Kconfig.debug
>> +++ b/lib/Kconfig.debug
>> @@ -399,6 +399,7 @@ config FRAME_WARN
>>  	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
>>  	default 2048 if PARISC
>>  	default 1536 if (!64BIT && XTENSA)
>> +	default 1280 if KASAN && !64BIT
>>  	default 1024 if !64BIT
>>  	default 2048 if 64BIT
>>  	help
>
> Note this also fixes 61 warnings when
>
>   (GCC && !GCC_PLUGIN_LATENT_ENTROPY)
>
> ... which as Arnd says should not be enabled by default.  We'll
> address that issue once this set has been applied.

Thanks a lot for checking this!

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

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Re: [PATCH v2 2/2] Kconfig.debug: Provide a little extra FRAME_WARN leeway when KASAN is enabled

[Nathan Chancellor]

On Fri, Nov 25, 2022 at 12:07:50PM +0000, Lee Jones wrote:
> When enabled, KASAN enlarges function's stack-frames.  Pushing quite a
> few over the current threshold.  This can mainly be seen on 32-bit
> architectures where the present limit (when !GCC) is a lowly
> 1024-Bytes.
> 
> Signed-off-by: Lee Jones <lee@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  lib/Kconfig.debug | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index c3c0b077ade33..82d475168db95 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -399,6 +399,7 @@ config FRAME_WARN
>  	default 2048 if GCC_PLUGIN_LATENT_ENTROPY
>  	default 2048 if PARISC
>  	default 1536 if (!64BIT && XTENSA)
> +	default 1280 if KASAN && !64BIT
>  	default 1024 if !64BIT
>  	default 2048 if 64BIT
>  	help
> -- 
> 2.38.1.584.g0f3c55d4c2-goog
> 

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Re: [PATCH v2 0/2] Fix a bunch of allmodconfig errors

[Andrew Morton]

On Fri, 25 Nov 2022 12:07:48 +0000 Lee Jones <lee@kernel.org> wrote:

> Since b339ec9c229aa ("kbuild: Only default to -Werror if COMPILE_TEST") WERROR 
> now defaults to COMPILE_TEST meaning that it's enabled for allmodconfig        
> builds.  This leads to some interesting failures, each resolved in this set.   

I'm not sure who this patchset is aimed at, so I'll take my usual
approach of grabbing it and seeing who complains.

> With this set applied, I am able to obtain a successful allmodconfig Arm build.

b339ec9c229aa is a year old and I've been doing arm allmodconfig for
ever.  What am I missing here?

A broken arm allmodconfig is pretty irritating - I'm thinking that a
fix should be backported into -stable kernels.  But I'm clearly missing
something here.


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Re: [PATCH v2 0/2] Fix a bunch of allmodconfig errors

[Lee Jones]

On Fri, 25 Nov 2022, Andrew Morton wrote:

> On Fri, 25 Nov 2022 12:07:48 +0000 Lee Jones <lee@kernel.org> wrote:
> 
> > Since b339ec9c229aa ("kbuild: Only default to -Werror if COMPILE_TEST") WERROR 
> > now defaults to COMPILE_TEST meaning that it's enabled for allmodconfig        
> > builds.  This leads to some interesting failures, each resolved in this set.   
> 
> I'm not sure who this patchset is aimed at, so I'll take my usual
> approach of grabbing it and seeing who complains.
> 
> > With this set applied, I am able to obtain a successful allmodconfig Arm build.
> 
> b339ec9c229aa is a year old and I've been doing arm allmodconfig for
> ever.  What am I missing here?
> 
> A broken arm allmodconfig is pretty irritating - I'm thinking that a
> fix should be backported into -stable kernels.  But I'm clearly missing
> something here.

I will be taking these through all applicable Stable kernels.

-- 
Lee Jones [李琼斯]

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Re: [PATCH v2 0/2] Fix a bunch of allmodconfig errors

[Andrew Morton]

On Fri, 25 Nov 2022 12:07:48 +0000 Lee Jones <lee@kernel.org> wrote:

> Since b339ec9c229aa ("kbuild: Only default to -Werror if COMPILE_TEST") WERROR 
> now defaults to COMPILE_TEST meaning that it's enabled for allmodconfig        
> builds.  This leads to some interesting failures, each resolved in this set.   

Oh, I get it.  Clang.  I'll tweak the above para to make that clearer.

cc:stable question still applies?  How much trouble will these build
errors be causing people for the next N years?

> With this set applied, I am able to obtain a successful allmodconfig Arm build.

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