Re: [PATCH 1/2] powerpc: Send SIGBUS on unaligned copy and paste

[Christophe Leroy <christophe.leroy@c-s.fr>]

Le 09/06/2016 à 08:01, Chris Smart a écrit :
> Calling ISA 3.0 instructions copy, copy_first, paste and paste_last
> generates an alignment fault when copying or pasting unaligned
> data (128 byte). We catch this and send SIGBUS to the userspace
> process that caused it.
>
> We do not emulate these because paste may contain additional metadata
> when pasting to a co-processor and paste_last is the synchronisation
> point for preceding copy/paste sequences.
>
> Thanks to Michael Neuling <mikey@neuling.org> for his help.
>
> Signed-off-by: Chris Smart <chris@distroguy.com>
> ---
> arch/powerpc/kernel/align.c | 15 +++++++++++++++
> 1 file changed, 15 insertions(+)
>
> diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
> index 8e7cb8e2b21a..fcdf09476eec 100644
> --- a/arch/powerpc/kernel/align.c
> +++ b/arch/powerpc/kernel/align.c
> @@ -875,6 +875,21 @@ int fix_alignment(struct pt_regs *regs)
>         return emulate_vsx(addr, reg, areg, regs, flags, nb, elsize);
>     }
> #endif
> +
> +    /*
> +     * ISA 3.0 (such as P9) copy, copy_first, paste and paste_last 
> alignment
> +     * check.
> +     *
> +     * Send a SIGBUS to the process that caused the fault.
> +     *
> +     * We do not emulate these because paste may contain additional 
> metadata
> +     * when pasting to a co-processor. Furthermore, paste_last is the
> +     * synchronisation point for preceding copy/paste sequences.
> +     */
> +    if ((instruction & 0xfc0006fe) == 0x7c00060c){

Can you define corresponding instruction and mask in 
arch/powerpc/include/asm/ppc-opcode.h
and use symbolic names here instead of raw values ?

Christophe