Hi all,

Today's linux-next merge of the arm64 tree got a conflict in:

  arch/arm64/kernel/cpufeature.c

between commit:

  228a26b91228 ("arm64: Use the clearbhb instruction in mitigations")

from Linus' tree and commit:

  def8c222f054 ("arm64: Add support of PAuth QARMA3 architected algorithm")

from the arm64 tree.

I fixed it up (see below) and can carry the fix as necessary. This
is now fixed as far as linux-next is concerned, but any non trivial
conflicts should be mentioned to your upstream maintainer when your tree
is submitted for merging.  You may also want to consider cooperating
with the maintainer of the conflicting tree to minimise any particularly
complex conflicts.

-- 
Cheers,
Stephen Rothwell

diff --cc arch/arm64/kernel/cpufeature.c
index d33687673f6b,32aa0eb3ed68..000000000000
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@@ -231,7 -226,10 +231,11 @@@ static const struct arm64_ftr_bits ftr_
  };
  
  static const struct arm64_ftr_bits ftr_id_aa64isar2[] = {
 +	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_HIGHER_SAFE, ID_AA64ISAR2_CLEARBHB_SHIFT, 4, 0),
+ 	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ 		       FTR_STRICT, FTR_EXACT, ID_AA64ISAR2_APA3_SHIFT, 4, 0),
+ 	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
+ 		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_GPA3_SHIFT, 4, 0),
  	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_RPRES_SHIFT, 4, 0),
  	ARM64_FTR_END,
  };

On Wed, Mar 09, 2022 at 09:42:35AM +1100, Stephen Rothwell wrote:
> Hi all,
> 
> Today's linux-next merge of the arm64 tree got a conflict in:
> 
>   arch/arm64/kernel/cpufeature.c
> 
> between commit:
> 
>   228a26b91228 ("arm64: Use the clearbhb instruction in mitigations")
> 
> from Linus' tree and commit:
> 
>   def8c222f054 ("arm64: Add support of PAuth QARMA3 architected algorithm")
> 
> from the arm64 tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc arch/arm64/kernel/cpufeature.c
> index d33687673f6b,32aa0eb3ed68..000000000000
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@@ -231,7 -226,10 +231,11 @@@ static const struct arm64_ftr_bits ftr_
>   };
>   
>   static const struct arm64_ftr_bits ftr_id_aa64isar2[] = {
>  +	ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_HIGHER_SAFE, ID_AA64ISAR2_CLEARBHB_SHIFT, 4, 0),
> + 	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
> + 		       FTR_STRICT, FTR_EXACT, ID_AA64ISAR2_APA3_SHIFT, 4, 0),
> + 	ARM64_FTR_BITS(FTR_VISIBLE_IF_IS_ENABLED(CONFIG_ARM64_PTR_AUTH),
> + 		       FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_GPA3_SHIFT, 4, 0),
>   	ARM64_FTR_BITS(FTR_VISIBLE, FTR_NONSTRICT, FTR_LOWER_SAFE, ID_AA64ISAR2_RPRES_SHIFT, 4, 0),
>   	ARM64_FTR_END,
>   };

This (and https://lore.kernel.org/r/20220309093832.01585172@canb.auug.org.au)
are due to the surprise spectre mitigations which landed yesterday. Now
that's all public, I'll merge those changes into our for-next/core branch
and these conflicts should all disappear.

Thanks,

Will