Re: [PATCH 1/7] signal/alpha: Document a conflict with SI_USER for SIGTRAP

[Richard Henderson]

On 07/18/2017 04:06 AM, Eric W. Biederman wrote:
> Setting si_code to __SI_FAULT results in a userspace seeing
> an si_code of 0.  This is the same si_code as SI_USER.  Posix
> and common sense requires that SI_USER not be a signal specific
> si_code.  As such this use of 0 for the si_code is a pretty
> horribly broken ABI.
>
> Given that alpha is on it's last legs I don't know that it is worth
> fixing this, but it is worth documenting what is going on so that
> no one decides to copy this bad decision.
>
> This was introduced during the 2.5 development cycle so this
> mess has had a long time for people to be able to depend upon it.
>
> v2: Added FPE_FIXME for alpha as Helge Deller<deller@xxxxxx>  pointed out
>      with his alternate patch one of the cases is SIGFPE not SIGTRAP.
>
> Cc: Helge Deller<deller@xxxxxx>
> Cc: Richard Henderson<rth@xxxxxxxxxxx>
> Cc: Ivan Kokshaysky<ink@xxxxxxxxxxxxxxxxxxxx>
> Cc: Matt Turner<mattst88@xxxxxxxxx>
> Cc:linux-alpha@xxxxxxxxxxxxxxx
> History Tree:https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
> Ref: 0a635c7a84cf ("Fill in siginfo_t.")
> Signed-off-by: "Eric W. Biederman"<ebiederm@xxxxxxxxxxxx>
> ---
>   arch/alpha/include/uapi/asm/siginfo.h | 14 ++++++++++++++
>   arch/alpha/kernel/traps.c             |  6 +++---
>   2 files changed, 17 insertions(+), 3 deletions(-)

Acked-by: Richard Henderson <rth@xxxxxxxxxxx>


r~