linux-kernel - Re: [PATCH V2 05/19] csky: System Call

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Date:   Wed, 4 Jul 2018 19:49:52 +0800
From:   Guo Ren <ren_guo@...ky.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Jason Cooper <jason@...edaemon.net>,
        c-sky_gcc_upstream@...ky.com, gnu-csky@...tor.com,
        thomas.petazzoni@...tlin.com, wbx@...ibc-ng.org,
        Greentime Hu <green.hu@...il.com>
Subject: Re: [PATCH V2 05/19] csky: System Call

On Tue, Jul 03, 2018 at 09:53:48PM +0200, Arnd Bergmann wrote:
> We really need all new architectures to use the generic syscall ABI,
> see below for the details.
Ok, follow the rules.

> > +#define __ARCH_WANT_OLD_READDIR
> > +#define __ARCH_WANT_RENAMEAT
> > +#define __ARCH_WANT_STAT64
> > +#define __ARCH_WANT_SYS_ALARM
> > +#define __ARCH_WANT_SYS_CLONE
> > +#define __ARCH_WANT_SYS_FORK
> > +#define __ARCH_WANT_SYS_GETHOSTNAME
> > +#define __ARCH_WANT_SYS_GETPGRP
> > +#define __ARCH_WANT_SYS_IPC
> > +#define __ARCH_WANT_SYS_LLSEEK
> > +#define __ARCH_WANT_SYS_NICE
> > +#define __ARCH_WANT_SYS_OLD_GETRLIMIT
> > +#define __ARCH_WANT_SYS_OLDUMOUNT
> > +#define __ARCH_WANT_SYS_PAUSE
> > +#define __ARCH_WANT_SYS_SIGNAL
> > +#define __ARCH_WANT_SYS_SIGPENDING
> > +#define __ARCH_WANT_SYS_SIGPROCMASK
> > +#define __ARCH_WANT_SYS_SOCKETCALL
> > +#define __ARCH_WANT_SYS_TIME
> > +#define __ARCH_WANT_SYS_UTIME
> > +#define __ARCH_WANT_SYS_VFORK
> > +#define __ARCH_WANT_SYS_WAITPID
> 
> I think these all need to be removed, with the exception of
> __ARCH_WANT_SYS_CLONE. It would be nice though to change
> the imlpementation in the kernel so we no longer need to set that
> either.
Ok.

 
> > +#define __NR_set_thread_area   (__NR_arch_specific_syscall + 0)
> > +__SYSCALL(__NR_set_thread_area, sys_set_thread_area)
> > +#define __NR_ipc               (__NR_arch_specific_syscall + 1)
> > +__SYSCALL(__NR_ipc, sys_ipc)
> > +#define __NR_socketcall                (__NR_arch_specific_syscall + 2)
> > +__SYSCALL(__NR_socketcall, sys_socketcall)
> > +#define __NR_ugetrlimit                (__NR_arch_specific_syscall + 3)
> > +__SYSCALL(__NR_ugetrlimit, sys_getrlimit)
> > +#define __NR_cacheflush                (__NR_arch_specific_syscall + 4)
> > +__SYSCALL(__NR_cacheflush, sys_cacheflush)
> > +#define __NR_sysfs             (__NR_arch_specific_syscall + 5)
> > +__SYSCALL(__NR_sysfs, sys_sysfs)
> > +
> > +__SYSCALL(__NR_fadvise64_64, sys_csky_fadvise64_64)
> 
> We definitely don't want ipc, socketcall, ugetrlimit, or sysfs.
Ok, remove them.
 
> For fadvise64_64, please redefine the symbol name so the
> table points at the right entry.
We need exchange the args for abiv1. loff_t is 64bit and abiv1 need
8-bytes align in args.
/*
 * for abiv1 the 64bits args should be even th, So we need mov the advice forward.
 */
SYSCALL_DEFINE4(csky_fadvise64_64,
	int, fd,
	int, advice,
	loff_t, offset,
	loff_t, len)
{
	return sys_fadvise64_64(fd, offset, len, advice);
}

> 
> I'm not completely sure about set_thread_area, can you explain
> what you need that for?
In abiv1 there is no tls register, so we use "trap 3" for csky_get_tls
defined in arch/csky/kernel/entry.S to get tls.

Also we use set_thread_area to set tls in kernel.

For abiv2 it has r31 for tls-reg, but we still keep the mechanism.

> > +#define __NR_setgroups32       __NR_setgroups
> > +#define __NR_getgid32          __NR_getgid
> > +#define __NR_getgroups32       __NR_getgroups
> > +#define __NR_setuid32          __NR_setuid
> > +#define __NR_setgid32          __NR_setgid
> > +#define __NR_getresgid32       __NR_getresgid
> > +#define __NR_setfsuid32                __NR_setfsuid
> > +#define __NR_setfsgid32                __NR_setfsgid
> > +#define __NR_fchown32          __NR_fchown
> > +#define __NR_geteuid32         __NR_geteuid
> > +#define __NR_getegid32         __NR_getegid
> > +#define __NR_getresuid32       __NR_getresuid
> > +#define __NR_setresuid32       __NR_setresuid
> > +#define __NR_setresgid32       __NR_setresgid
> > +#define __NR_setreuid32                __NR_setreuid
> > +#define __NR_setregid32                __NR_setregid
> > +#define __NR__llseek           __NR_llseek
> 
> These should also get removed.
Ok.

> > +struct mmap_arg_struct {
> > +       unsigned long addr;
> > +       unsigned long len;
> > +       unsigned long prot;
> > +       unsigned long flags;
> > +       unsigned long fd;
> > +       unsigned long offset;
> > +};
> > +
> > +SYSCALL_DEFINE1(mmap,
> > +       struct mmap_arg_struct *, arg)
> > +{
> > +       struct mmap_arg_struct a;
> > +
> > +       if (copy_from_user(&a, arg, sizeof(a)))
> > +               return -EINVAL;
> > +
> > +       if (unlikely(a.offset & ~PAGE_MASK))
> > +               return -EINVAL;
> > +
> > +       return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, a.offset >> PAGE_SHIFT);
> > +}
> 
> This can be removed since there is mmap2()
Ok.

 Guo Ren