This is a note to let you know that I have just added a patch titled
MIPS: ptrace: Fix FP context restoration FCSR regression
to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree
which can be found at:
https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue
This patch is scheduled to be released in version 4.2.8-ckt12.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
---8<------------------------------------------------------------
>From 1e9c4800d6960e4a9eb52af08a80346f45b92e58 Mon Sep 17 00:00:00 2001
From: "Maciej W. Rozycki" <macro@xxxxxxxxxx>
Date: Thu, 12 May 2016 10:18:27 +0100
Subject: MIPS: ptrace: Fix FP context restoration FCSR regression
commit 4249548454f7ba4581aeee26bd83f42b48a14d15 upstream.
Fix a floating-point context restoration regression introduced with
commit 9b26616c8d9d ("MIPS: Respect the ISA level in FCSR handling")
that causes a Floating Point exception and consequently a kernel oops
with hard float configurations when one or more FCSR Enable and their
corresponding Cause bits are set both at a time via a ptrace(2) call.
To do so reinstate Cause bit masking originally introduced with commit
b1442d39fac2 ("MIPS: Prevent user from setting FCSR cause bits") to
address this exact problem and then inadvertently removed from the
PTRACE_SETFPREGS request with the commit referred above.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/13238/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
arch/mips/kernel/ptrace.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index e933a30..d56642a 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -175,6 +175,7 @@ int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
}
__get_user(value, data + 64);
+ value &= ~FPU_CSR_ALL_X;
fcr31 = child->thread.fpu.fcr31;
mask = boot_cpu_data.fpu_msk31;
child->thread.fpu.fcr31 = (value & ~mask) | (fcr31 & mask);
--
2.7.4
