From: Max Filippov <jcmvbkbc@gmail.com>
Date: Mon, 14 Oct 2013 22:22:42 +0000 (+0400)
Subject: xtensa: fix fast_syscall_spill_registers_fixup
X-Git-Tag: v3.12~32^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=244066f4be8ce2dc2d2d60f01bceeba55c71a783;p=pandora-kernel.git

xtensa: fix fast_syscall_spill_registers_fixup

fast_syscall_spill_registers_fixup was not correctly updated by the
'keep a3 and excsave1 on entry to exception handlers' patch: it doesn't
preserve a3 that it gets on entry, breaking _spill_registers in case of
page fault on stack during register spilling, leading to unhandled
exception in kernel mode.

Preserve a3 by saving it in the original _spill_registers stack frame's
a3 during exception handling and restoring it afterwards.

Also fix comments and function bounds annotations.

Reported-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Chris Zankel <chris@zankel.net>
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