Re: [PATCH] arm64: compat: Fix syscall number of compat_clock_getres

From: Nick Desaulniers <ndesaulniers@google.com>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	"# 3.4.x" <stable@vger.kernel.org>
Subject: Re: [PATCH] arm64: compat: Fix syscall number of compat_clock_getres
Date: Thu, 19 Mar 2020 08:39:36 -0700	[thread overview]
Message-ID: <CAKwvOdnnsE2FyqajP4_FrwpgekptfLJsr3J9EgB3Ac37NgZszQ@mail.gmail.com> (raw)
In-Reply-To: <20200319141138.19343-1-vincenzo.frascino@arm.com>

On Thu, Mar 19, 2020 at 7:11 AM Vincenzo Frascino
<vincenzo.frascino@arm.com> wrote:
>
> The syscall number of compat_clock_getres was erroneously set to 247
> instead of 264. This causes the vDSO fallback of clock_getres to land
> on the wrong syscall.
>
> Address the issue fixing the syscall number of compat_clock_getres.
>
> Fixes: 53c489e1dfeb6 ("arm64: compat: Add missing syscall numbers")
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
>  arch/arm64/include/asm/unistd.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
> index 1dd22da1c3a9..803039d504de 100644
> --- a/arch/arm64/include/asm/unistd.h
> +++ b/arch/arm64/include/asm/unistd.h
> @@ -25,8 +25,8 @@
>  #define __NR_compat_gettimeofday       78
>  #define __NR_compat_sigreturn          119
>  #define __NR_compat_rt_sigreturn       173
> -#define __NR_compat_clock_getres       247
>  #define __NR_compat_clock_gettime      263
> +#define __NR_compat_clock_getres       264

This seems to match up with the glibc sources:
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/arm/arch-syscall.h;h=c6554a8a6a6e7fe3359f1272f619c3da7c90629b;hb=HEAD#l27
Here's bionic's headers for good measure:
https://android.googlesource.com/platform/bionic/+/refs/heads/master/libc/kernel/uapi/asm-arm/asm/unistd-common.h#240

I assume the _compat_ prefixes are the aarch32 syscall numbers?
Otherwise here's the list for aarch64:
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/aarch64/arch-syscall.h;h=c8471947b9c209be6add1e528f892f1a6c54f966;hb=HEAD

Looks like 247 was __NR_io_cancel; that's a subtle bug I'm glad was noticed!

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

>  #define __NR_compat_clock_gettime64    403
>  #define __NR_compat_clock_getres_time64        406
>
> --
> 2.25.1
>
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-- 
Thanks,
~Nick Desaulniers