linux-kernel - Re: [PATCH] KVM: selftests: Track width of arm64's timer counter as "int", not "uint64

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <aNbt9NH2iVLPeIDX@linux.dev>
Date: Fri, 26 Sep 2025 12:48:04 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org,
	Sebastian Ott <sebott@...hat.com>
Subject: Re: [PATCH] KVM: selftests: Track width of arm64's timer counter as
 "int", not "uint64_t"

On Fri, Sep 26, 2025 at 08:58:38AM -0700, Sean Christopherson wrote:
> Store the width of arm64's timer counter as an "int", not a "uint64_t".
> ilog2() returns an "int", and more importantly using what is an "unsigned
> long" under the hood makes clang unhappy due to a type mismatch when
> clamping the width to a sane value.
> 
>   arm64/arch_timer_edge_cases.c:1032:10: error: comparison of distinct pointer types
>      ('typeof (width) *' (aka 'unsigned long *') and 'typeof (56) *' (aka 'int *'))
>      [-Werror,-Wcompare-distinct-pointer-types]
>    1032 |         width = clamp(width, 56, 64);
>         |                 ^~~~~~~~~~~~~~~~~~~~
>   tools/include/linux/kernel.h:47:45: note: expanded from macro 'clamp'
>      47 | #define clamp(val, lo, hi)      min((typeof(val))max(val, lo), hi)
>         |                                                  ^~~~~~~~~~~~
>   tools/include/linux/kernel.h:33:17: note: expanded from macro 'max'
>      33 |         (void) (&_max1 == &_max2);              \
>         |                 ~~~~~~ ^  ~~~~~~
>   tools/include/linux/kernel.h:39:9: note: expanded from macro 'min'
>      39 |         typeof(x) _min1 = (x);                  \
>         |                ^
> 
> Fixes: fad4cf944839 ("KVM: arm64: selftests: Determine effective counter width in arch_timer_edge_cases")
> Cc: Sebastian Ott <sebott@...hat.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

In the absence of a __careless_clamp() :)

Reviewed-by: Oliver Upton <oliver.upton@...ux.dev>

Thanks,
Oliver