From: Huacai Chen <chenhuacai@gmail.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Huacai Chen <chenhuacai@loongson.cn>,
Arnd Bergmann <arnd@arndb.de>, Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Airlie <airlied@linux.ie>, Jonathan Corbet <corbet@lwn.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-arch <linux-arch@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Xuefeng Li <lixuefeng@loongson.cn>,
Yanteng Si <siyanteng@loongson.cn>,
Jiaxun Yang <jiaxun.yang@flygoat.com>
Subject: Re: [PATCH V4 11/22] LoongArch: Add process management
Date: Sun, 3 Oct 2021 17:10:58 +0800 [thread overview]
Message-ID: <CAAhV-H5ndJvpcZ3P0P-65_-MFmpLuZ7k8Be6vUAFaL--sXDtxg@mail.gmail.com> (raw)
In-Reply-To: <YVkZ7jLWJpvZz9us@zeniv-ca.linux.org.uk>
Hi, Al,
On Sun, Oct 3, 2021 at 10:50 AM Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, Sep 27, 2021 at 02:42:48PM +0800, Huacai Chen wrote:
>
> > +/*
> > + * Does the process account for user or for system time?
> > + */
> > +#define user_mode(regs) (((regs)->csr_prmd & PLV_MASK) == PLV_USER)
> > +
> > +static inline int is_syscall_success(struct pt_regs *regs)
> > +{
> > + return !regs->regs[7];
> > +}
> >
> > +static inline long regs_return_value(struct pt_regs *regs)
> > +{
> > + if (is_syscall_success(regs) || !user_mode(regs))
> > + return regs->regs[4];
> > + else
> > + return -regs->regs[4];
> > +}
>
> Huh??? That looks like you've copied those from MIPS, but on MIPS we have
> things like
> li t0, -EMAXERRNO - 1 # error?
> sltu t0, t0, v0
> sd t0, PT_R7(sp) # set error flag
> beqz t0, 1f
>
> ld t1, PT_R2(sp) # syscall number
> dnegu v0 # error
> sd t1, PT_R0(sp) # save it for syscall restarting
> 1: sd v0, PT_R2(sp) # result
> right after the call of sys_...(), along with the restart logics
> looking like
> if (regs->regs[0]) {
> switch(regs->regs[2]) {
> case ERESTART_RESTARTBLOCK:
> case ERESTARTNOHAND:
> IOW, syscall return values from -EMAXERRNO to -1 are negated, with
> regs[7] set accordingly. Nothing of that sort is done in your
> patchset after syscall, and if it had been, your restart logics in
> signal handling would've been wrong anyway.
>
> What's going on there?
Sorry, the code derived from MIPS is wrong here, regs_return_value
should simply return regs->regs[4].
Huacai
next prev parent reply other threads:[~2021-10-03 9:11 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-27 6:42 [PATCH V4 00/22] arch: Add basic LoongArch support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 01/22] Documentation: LoongArch: Add basic documentations Huacai Chen
2021-09-27 6:42 ` [PATCH V4 02/22] Documentation/zh_CN: Add basic LoongArch documentations Huacai Chen
2021-09-27 6:42 ` [PATCH V4 03/22] LoongArch: Add elf-related definitions Huacai Chen
2021-09-27 6:42 ` [PATCH V4 04/22] LoongArch: Add writecombine support for drm Huacai Chen
2021-09-27 6:42 ` [PATCH V4 05/22] LoongArch: Add build infrastructure Huacai Chen
2021-09-27 6:42 ` [PATCH V4 06/22] LoongArch: Add CPU definition headers Huacai Chen
2021-09-30 15:30 ` Xi Ruoyao
2021-10-02 10:49 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 07/22] LoongArch: Add atomic/locking headers Huacai Chen
2021-10-01 10:52 ` Peter Zijlstra
2021-10-02 11:47 ` Huacai Chen
2021-10-01 11:04 ` Peter Zijlstra
2021-10-02 11:05 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 08/22] LoongArch: Add other common headers Huacai Chen
2021-09-27 6:42 ` [PATCH V4 09/22] LoongArch: Add boot and setup routines Huacai Chen
2021-09-27 6:52 ` Ard Biesheuvel
2021-09-29 3:24 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 10/22] LoongArch: Add exception/interrupt handling Huacai Chen
2021-09-27 6:42 ` [PATCH V4 11/22] LoongArch: Add process management Huacai Chen
2021-10-03 2:48 ` Al Viro
2021-10-03 9:10 ` Huacai Chen [this message]
2021-09-27 6:42 ` [PATCH V4 12/22] LoongArch: Add memory management Huacai Chen
2021-09-27 6:42 ` [PATCH V4 13/22] LoongArch: Add system call support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 14/22] LoongArch: Add signal handling support Huacai Chen
2021-10-03 2:29 ` Al Viro
2021-10-03 9:09 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 15/22] LoongArch: Add elf and module support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 16/22] LoongArch: Add misc common routines Huacai Chen
2021-10-01 11:03 ` Peter Zijlstra
2021-10-02 10:56 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 17/22] LoongArch: Add some library functions Huacai Chen
2021-09-27 6:42 ` [PATCH V4 18/22] LoongArch: Add PCI controller support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 19/22] LoongArch: Add VDSO and VSYSCALL support Huacai Chen
2021-09-30 15:43 ` Xi Ruoyao
2021-10-02 10:53 ` Huacai Chen
2021-10-02 12:13 ` Xi Ruoyao
2021-10-02 12:44 ` Huacai Chen
2021-09-27 6:42 ` [PATCH V4 20/22] LoongArch: Add multi-processor (SMP) support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 21/22] LoongArch: Add Non-Uniform Memory Access (NUMA) support Huacai Chen
2021-09-27 6:42 ` [PATCH V4 22/22] LoongArch: Add Loongson-3 default config file Huacai Chen
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