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Message-ID: <36f11c19-0cc5-cf56-b41d-6cad4878ddb3@xen0n.name>
Date: Thu, 19 May 2022 01:17:19 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Huacai Chen <chenhuacai@...il.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Huacai Chen <chenhuacai@...ngson.cn>,
Arnd Bergmann <arnd@...db.de>,
Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
David Airlie <airlied@...ux.ie>,
Jonathan Corbet <corbet@....net>,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-arch <linux-arch@...r.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>,
Xuefeng Li <lixuefeng@...ngson.cn>,
Yanteng Si <siyanteng@...ngson.cn>,
Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH V11 14/22] LoongArch: Add signal handling support
On 5/19/22 00:54, Huacai Chen wrote:
> Hi, Eric,
>
> On Thu, May 19, 2022 at 12:40 AM Eric W. Biederman
> <ebiederm@...ssion.com> wrote:
>> Huacai Chen <chenhuacai@...ngson.cn> writes:
>>
>>> Add ucontext/sigcontext definition and signal handling support for
>>> LoongArch.
>>>
>>> Cc: Eric Biederman <ebiederm@...ssion.com>
>>> Cc: Al Viro <viro@...iv.linux.org.uk>
>>> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
>>> ---
>>> arch/loongarch/include/uapi/asm/sigcontext.h | 44 ++
>>> arch/loongarch/include/uapi/asm/signal.h | 13 +
>>> arch/loongarch/include/uapi/asm/ucontext.h | 35 ++
>>> arch/loongarch/kernel/signal.c | 566 +++++++++++++++++++
>>> 4 files changed, 658 insertions(+)
>>> create mode 100644 arch/loongarch/include/uapi/asm/sigcontext.h
>>> create mode 100644 arch/loongarch/include/uapi/asm/signal.h
>>> create mode 100644 arch/loongarch/include/uapi/asm/ucontext.h
>>> create mode 100644 arch/loongarch/kernel/signal.c
>>>
>>> diff --git a/arch/loongarch/include/uapi/asm/sigcontext.h b/arch/loongarch/include/uapi/asm/sigcontext.h
>>> new file mode 100644
>>> index 000000000000..be3d3c6ac83e
>>> --- /dev/null
>>> +++ b/arch/loongarch/include/uapi/asm/sigcontext.h
>>> @@ -0,0 +1,44 @@
>>> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
>>> +/*
>>> + * Author: Hanlu Li <lihanlu@...ngson.cn>
>>> + * Huacai Chen <chenhuacai@...ngson.cn>
>>> + *
>>> + * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
>>> + */
>>> +#ifndef _UAPI_ASM_SIGCONTEXT_H
>>> +#define _UAPI_ASM_SIGCONTEXT_H
>>> +
>>> +#include <linux/types.h>
>>> +#include <linux/posix_types.h>
>>> +
>>> +/* FP context was used */
>>> +#define SC_USED_FP (1 << 0)
>>> +/* Address error was due to memory load */
>>> +#define SC_ADDRERR_RD (1 << 30)
>>> +/* Address error was due to memory store */
>>> +#define SC_ADDRERR_WR (1 << 31)
>>> +
>>> +struct sigcontext {
>>> + __u64 sc_pc;
>>> + __u64 sc_regs[32];
>>> + __u32 sc_flags;
>>> + __u64 sc_extcontext[0] __attribute__((__aligned__(16)));
>>> +};
>>> +
>>> +#define CONTEXT_INFO_ALIGN 16
>>> +struct _ctxinfo {
>>> + __u32 magic;
>>> + __u32 size;
>>> + __u64 padding; /* padding to 16 bytes */
>>> +};
>> This is probably something I a missing but what is struct _ctxinfo and
>> why is it in a uapi header?
>>
>> I don't see anything else in the uapi implementation using it.
> This is used by get_ctx_through_ctxinfo() in signal.c and I think
> similar function is also needed by userspace.
>
> Its name is once before called context_info but conflict with another
> software, then I want to use ctx_info but conflict with another kernel
> struct. :(
>> Symbols that start with an underscore "_" are reserved and should not
>> be used in general, and especially not in uapi header files.
> Then, maybe we can use sctx_info here?
Actually it seems to me that this struct is the header of each
sc_extcontext; i.e. one struct sigcontext with 0~N trailing
"sc_extcontext", and each "sc_extcontext" consists of one "struct
_ctxinfo" header plus the real content. For now there's only the FPU
context but the LSX/LASX/LBT contexts will come later. The "magic" and
"size" fields also matches the definitions following.
So I'd suggest something like "struct sc_extcontext_head" while naming
the individual contexts like "struct sc_extcontext_foo", e.g. "struct
sc_extcontext_fpu". The "sc_extcontext" part could use some further
abbreviation but the end result should be something intuitive.
>
> Huacai
>> Eric
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