Re: [PATCH V10 14/22] LoongArch: Add signal handling support

[WANG Xuerui]

Hi,

On 5/15/22 21:48, Huacai Chen wrote:
> diff --git a/arch/loongarch/include/uapi/asm/sigcontext.h b/arch/loongarch/include/uapi/asm/sigcontext.h
> new file mode 100644
> index 000000000000..efeb8b3f8236
> --- /dev/null
> +++ b/arch/loongarch/include/uapi/asm/sigcontext.h
> @@ -0,0 +1,63 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +/*
> + * Author: Hanlu Li <lihanlu@xxxxxxxxxxx>
> + *         Huacai Chen <chenhuacai@xxxxxxxxxxx>
> + *
> + * 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 USED_FP                      (1 << 0)
> +/* Load/Store access flags for address error */
> +#define ADRERR_RD            (1 << 30)
> +#define ADRERR_WR            (1 << 31)
> > I've searched GitHub globally, and my local glibc checkout, for usages
> > of these 3 constants, and there seems to be none; please consider
> > removing these if doable. We don't want cruft in uapi right from the
> > beginning.
> They will be used in our glibc, I promise.
Okay then. Seems simple enough, and from my quick grepping these appear 
to be original creations -- not carried over from somewhere else, so 
it's already highly likely that some of the userland tools need these 
anyway, just not released yet.
> > > +
> > > +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 */
> > > +};
> > > +
> > > +/* FPU context */
> > > +#define FPU_CTX_MAGIC                0x46505501
> > > +#define FPU_CTX_ALIGN                8
> > > +struct fpu_context {
> > > +     __u64   regs[32];
> > > +     __u64   fcc;
> > > +     __u32   fcsr;
> > > +};
> > The 3 structs above should already see usage downstream (glibc and other
> > low-level friends), so they probably shouldn't be touched by now. At
> > least I can't see problems.
> > > +
> > > +/* LSX context */
> > > +#define LSX_CTX_MAGIC                0x53580001
> > > +#define LSX_CTX_ALIGN                16
> > > +struct lsx_context {
> > > +     __u64   regs[2*32];
> > > +     __u64   fcc;
> > > +     __u32   fcsr;
> > > +     __u32   vcsr;
> > > +};
> > > +
> > > +/* LASX context */
> > > +#define LASX_CTX_MAGIC               0x41535801
> > > +#define LASX_CTX_ALIGN               32
> > > +struct lasx_context {
> > > +     __u64   regs[4*32];
> > > +     __u64   fcc;
> > > +     __u32   fcsr;
> > > +     __u32   vcsr;
> > > +};
> > Do we want to freeze the LSX/LASX layout this early, before any detail
> > of said extension are published? We'll need to update kernel later
> > anyway, so I'd recommend leaving them out for the initial bring-up.
> Yes, they are freezed.
Okay too, I remember these are the same values as in the old world, so 
it should be easy to support both worlds at least in this regard.
> > > +
> > > +#endif /* _UAPI_ASM_SIGCONTEXT_H */
Then I have no problems with this patch then ;-)