[3.16.y-ckt stable] Patch "MIPS: fix EVA & non-SMP non-FPU FP context signal handling" has been added to staging queue

[Luis Henriques <luis.henriques@xxxxxxxxxxxxx>]

This is a note to let you know that I have just added a patch titled

    MIPS: fix EVA & non-SMP non-FPU FP context signal handling

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt3.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 58697c4f6561860fab7372b615579dc86c9f4d2f Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@xxxxxxxxxx>
Date: Tue, 28 Oct 2014 11:25:51 +0000
Subject: MIPS: fix EVA & non-SMP non-FPU FP context signal handling

commit 14fa12df1d6bc1d3389a0fa842e0ebd8e8a9af26 upstream.

The save_fp_context & restore_fp_context pointers were being assigned
to the wrong variables if either:

  - The kernel is configured for UP & runs on a system without an FPU,
    since b2ead5282885 "MIPS: Move & rename
    fpu_emulator_{save,restore}_context".

  - The kernel is configured for EVA, since ca750649e08c "MIPS: kernel:
    signal: Prevent save/restore FPU context in user memory".

This would lead to FP context being clobbered incorrectly when setting
up a sigcontext, then the garbage values being saved uselessly when
returning from the signal.

Fix by swapping the pointer assignments appropriately.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/8230/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 arch/mips/kernel/signal.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
index 9e60d117e41e..394e2b12a3ba 100644
--- a/arch/mips/kernel/signal.c
+++ b/arch/mips/kernel/signal.c
@@ -676,13 +676,13 @@ static int signal_setup(void)
 		save_fp_context = _save_fp_context;
 		restore_fp_context = _restore_fp_context;
 	} else {
-		save_fp_context = copy_fp_from_sigcontext;
-		restore_fp_context = copy_fp_to_sigcontext;
+		save_fp_context = copy_fp_to_sigcontext;
+		restore_fp_context = copy_fp_from_sigcontext;
 	}
 #endif /* CONFIG_SMP */
 #else
-	save_fp_context = copy_fp_from_sigcontext;;
-	restore_fp_context = copy_fp_to_sigcontext;
+	save_fp_context = copy_fp_to_sigcontext;
+	restore_fp_context = copy_fp_from_sigcontext;
 #endif

 	return 0;