From: Kees Cook <keescook@chromium.org>
To: David Gow <davidgow@google.com>
Cc: Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Al Viro <viro@zeniv.linux.org.uk>,
x86@kernel.org, linux-um@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] um: Cleanup syscall_handler_t definition/cast, fix warning
Date: Thu, 17 Feb 2022 09:29:14 -0800 [thread overview]
Message-ID: <202202170928.F02D6F41@keescook> (raw)
In-Reply-To: <20220210034353.1065703-1-davidgow@google.com>
On Thu, Feb 10, 2022 at 11:43:53AM +0800, David Gow wrote:
> The syscall_handler_t type for x86_64 was defined as 'long (*)(void)',
> but always cast to 'long (*)(long, long, long, long, long, long)' before
> use. This now triggers a warning (see below).
>
> Define syscall_handler_t as the latter instead, and remove the cast.
> This simplifies the code, and fixes the warning.
>
> Warning:
> In file included from ../arch/um/include/asm/processor-generic.h:13
> from ../arch/x86/um/asm/processor.h:41
> from ../include/linux/rcupdate.h:30
> from ../include/linux/rculist.h:11
> from ../include/linux/pid.h:5
> from ../include/linux/sched.h:14
> from ../include/linux/ptrace.h:6
> from ../arch/um/kernel/skas/syscall.c:7:
> ../arch/um/kernel/skas/syscall.c: In function ‘handle_syscall’:
> ../arch/x86/um/shared/sysdep/syscalls_64.h:18:11: warning: cast between incompatible function types from ‘long int (*)(void)’ to ‘long int (*)(long int, long int, long int, long int, long int, long int)’ [
> -Wcast-function-type]
> 18 | (((long (*)(long, long, long, long, long, long)) \
> | ^
> ../arch/x86/um/asm/ptrace.h:36:62: note: in definition of macro ‘PT_REGS_SET_SYSCALL_RETURN’
> 36 | #define PT_REGS_SET_SYSCALL_RETURN(r, res) (PT_REGS_AX(r) = (res))
> | ^~~
> ../arch/um/kernel/skas/syscall.c:46:33: note: in expansion of macro ‘EXECUTE_SYSCALL’
> 46 | EXECUTE_SYSCALL(syscall, regs));
> | ^~~~~~~~~~~~~~~
>
> Signed-off-by: David Gow <davidgow@google.com>
Thanks for this! I was just about to go figure this out too. :)
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
--
Kees Cook
prev parent reply other threads:[~2022-02-17 17:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-10 3:43 [PATCH] um: Cleanup syscall_handler_t definition/cast, fix warning David Gow
2022-02-17 17:29 ` Kees Cook [this message]
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