Re: [PATCH v11 08/12] signal, x86: add SIGSYS info and make itsynchronous.

From: Oleg Nesterov
Date: Mon Feb 27 2012 - 12:29:44 EST


On 02/24, Will Drewry wrote:
>
> To ensure that SIGSYS delivery occurs on return from the triggering
> system call, SIGSYS is added to the SYNCHRONOUS_MASK macro.

Hmm. Can't understand... please help.

> #define SYNCHRONOUS_MASK \
> (sigmask(SIGSEGV) | sigmask(SIGBUS) | sigmask(SIGILL) | \
> - sigmask(SIGTRAP) | sigmask(SIGFPE))
> + sigmask(SIGTRAP) | sigmask(SIGFPE) | sigmask(SIGSYS))

Why?

SYNCHRONOUS_MASK just tells dequeue_signal() "pick them first".
This is needed to make sure that the handler for, say SIGSEGV,
can use ucontext->ip as a faulting addr.

But seccomp adds info->si_call_addr, this looks unneeded.

Oleg.

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