linux-kernel - Re: [PATCH 05/13] riscv: compat: syscall: Add compat_sys_call

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Date:   Wed, 22 Dec 2021 20:43:15 +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 05/13] riscv: compat: syscall: Add compat_sys_call_table implementation

On Wed, Dec 22, 2021 at 2:15 AM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Tue, Dec 21, 2021 at 5:35 PM <guoren@...nel.org> wrote:
> >
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > Implement compat_syscall_table.c with compat_sys_call_table & fixup
> > system call such as truncate64,pread64,fallocate which need two
> > regs to indicate 64bit-arg (copied from arm64).
> >
> > Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> > ---
> >  arch/riscv/include/asm/syscall.h         |  3 +
> >  arch/riscv/kernel/compat_syscall_table.c | 84 ++++++++++++++++++++++++
>
> Same here, I think most of these should go next to the actual syscalls, with the
> duplicates removed from other platforms,
Agree, I will try that next version.

>
> > +#define __SYSCALL_COMPAT
> > +#undef __LP64__
>
> What is the #undef for?

See arch/riscv/include/uapi/asm/unistd.h:

#ifdef __LP64__
#define __ARCH_WANT_NEW_STAT
#define __ARCH_WANT_SET_GET_RLIMIT
#endif /* __LP64__ */


>
> > +SYSCALL_DEFINE6(mmap2, unsigned long, addr, unsigned long, len,
> > +       unsigned long, prot, unsigned long, flags,
> > +       unsigned long, fd, unsigned long, offset)
> > +{
> > +       if ((prot & PROT_WRITE) && (prot & PROT_EXEC))
> > +               if (unlikely(!(prot & PROT_READ)))
> > +                       return -EINVAL;
> > +
> > +       return ksys_mmap_pgoff(addr, len, prot, flags, fd, offset);
> > +}
>
> This is one that we may have to deal with separately, introducing
> sys_mmap_pgoff() was a mistake in my opinion, and we should just have
#if __BITS_PER_LONG == 32 || defined(__SYSCALL_COMPAT)
#define __SC_3264(_nr, _32, _64) __SYSCALL(_nr, _32)
#else
#define __SC_3264(_nr, _32, _64) __SYSCALL(_nr, _64)
#endif

#define __NR3264_mmap 222
__SC_3264(__NR3264_mmap, sys_mmap2, sys_mmap)

> added a sys_mmap2() for all architectures that don't explicitly override it.
That should be another patch, right? Let's keep it here.

>
>        Arnd



-- 
Best Regards
 Guo Ren

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