From: Ingo Molnar <mingo@elte.hu>
Date: Tue, 20 Jan 2009 08:31:49 +0000 (+0100)
Subject: Revert "x86: signal: change type of paramter for sys_rt_sigreturn()"
X-Git-Tag: v2.6.29-rc3~42^2~13
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=552b8aa4d1edcc1c764ff6f61a7686347a2d1827;p=pandora-kernel.git

Revert "x86: signal: change type of paramter for sys_rt_sigreturn()"

This reverts commit 4217458dafaa57d8e26a46f5d05ab8c53cf64191.

Justin Madru bisected this commit, it was causing weird Firefox
crashes.

The reason is that GCC mis-optimizes (re-uses) the on-stack parameters of
the calling frame, which corrupts the syscall return pt_regs state and
thus corrupts user-space register state.

So we go back to the slightly less clean but more optimization-safe
method of getting to pt_regs. Also add a comment to explain this.

Resolves: http://bugzilla.kernel.org/show_bug.cgi?id=12505

Reported-and-bisected-by: Justin Madru <jdm64@gawab.com>
Tested-by: Justin Madru <jdm64@gawab.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

Reading git-diff-tree failed