linux-kernel - Getting the way a SIGSEGV append when catching a SIGSEGV from within

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Message-ID: <bce22a1c127bf19825637bcd326c6f00@mx.sdfeu.org>
Date:   Mon, 27 Mar 2017 16:45:42 +0200
From:   none <ytrezq@...-eu.org>
To:     Linux Kernel <linux-kernel@...r.kernel.org>,
        linux-x86_64@...r.kernel.org
Subject: Getting the way a SIGSEGV append when catching a SIGSEGV from within

Hello,

There’s three way to perform an invalid memory access :

The attempt to execute/jump at an invalid address.
The attempt to read at an invalid address.
The attempt to write at an invalid address.

Determining the execute case with rt_sigaction is easy : the last value 
of eip match the value of the address which caused the segfault.

But how to know if the SIGSEGV occurred by a read or by a write attempt 
? In the same time shouldn’t that information belong in the mmu ?