linux-kernel - Re: [PATCH 01/13] syscalls: compat: Fix the missing part for __SYSCALL

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Message-ID: <CAJF2gTQciNaXk+_am=kS2uSwg6oGM4aJqiw_O5KN-DrHetf8nA@mail.gmail.com>
Date:   Wed, 22 Dec 2021 19:16:10 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Anup Patel <anup.patel@....com>,
        gregkh <gregkh@...uxfoundation.org>,
        liush <liush@...winnertech.com>, Wei Fu <wefu@...hat.com>,
        Drew Fustini <drew@...gleboard.org>,
        Wang Junqiang <wangjunqiang@...as.ac.cn>,
        Wei Wu (吴伟) <lazyparser@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-csky@...r.kernel.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH 01/13] syscalls: compat: Fix the missing part for __SYSCALL_COMPAT

On Wed, Dec 22, 2021 at 1:09 AM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Tue, Dec 21, 2021 at 5:35 PM <guoren@...nel.org> wrote:
> > diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> > index 4557a8b6086f..aafe5cfeb27c 100644
> > --- a/include/uapi/asm-generic/unistd.h
> > +++ b/include/uapi/asm-generic/unistd.h
> > @@ -383,7 +383,7 @@ __SYSCALL(__NR_syslog, sys_syslog)
> >
> >  /* kernel/ptrace.c */
> >  #define __NR_ptrace 117
> > -__SYSCALL(__NR_ptrace, sys_ptrace)
> > +__SC_COMP(__NR_ptrace, sys_ptrace, compat_sys_ptrace)
> >
>
> Right. We could merge sys_ptrace and compat_sys_ptrace() by adding
> a in_compat_syscall() check, but either way works.
>
> >  /* kernel/sched/core.c */
> >  #define __NR_sched_setparam 118
> > @@ -779,7 +779,7 @@ __SYSCALL(__NR_rseq, sys_rseq)
> >  #define __NR_kexec_file_load 294
> >  __SYSCALL(__NR_kexec_file_load,     sys_kexec_file_load)
> >  /* 295 through 402 are unassigned to sync up with generic numbers, don't use */
> > -#if __BITS_PER_LONG == 32
> > +#if defined(__SYSCALL_COMPAT) || __BITS_PER_LONG == 32
> >  #define __NR_clock_gettime64 403
> >  __SYSCALL(__NR_clock_gettime64, sys_clock_gettime)
>
> This part looks wrong, you expose clock_gettime64 to user space this way, both
> in asm/unistd.h and in the table.
>
>          Arnd

No, we only define __SYSCALL_COMPAT in compat_syscall_table.c. It
won't be expose to user space, because there is no __SYSCALL_COMPAT.

$ grep __SYSCALL_COMPAT * -r
arch/riscv/kernel/compat_syscall_table.c:#define __SYSCALL_COMPAT
                           ^^^^^^^^^^^^^^^^^^^^^^
include/uapi/asm-generic/unistd.h:#if __BITS_PER_LONG == 32 ||
defined(__SYSCALL_COMPAT)
include/uapi/asm-generic/unistd.h:#ifdef __SYSCALL_COMPAT
include/uapi/asm-generic/unistd.h:#if defined(__SYSCALL_COMPAT) ||
__BITS_PER_LONG == 32
include/uapi/asm-generic/unistd.h:#if __BITS_PER_LONG == 64 &&
!defined(__SYSCALL_COMPAT)
tools/include/uapi/asm-generic/unistd.h:#if __BITS_PER_LONG == 32 ||
defined(__SYSCALL_COMPAT)
tools/include/uapi/asm-generic/unistd.h:#ifdef __SYSCALL_COMPAT
tools/include/uapi/asm-generic/unistd.h:#if defined(__SYSCALL_COMPAT)
|| __BITS_PER_LONG == 32
tools/include/uapi/asm-generic/unistd.h:#if __BITS_PER_LONG == 64 &&
!defined(__SYSCALL_COMPAT)

-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/