This is a note to let you know that I've just added the patch titled
MIPS: Fix bnezc/jialc return address calculation
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mips-fix-bnezc-jialc-return-address-calculation.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1a73d9310e093fc3adffba4d0a67b9fab2ee3f63 Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@xxxxxxxxxx>
Date: Fri, 2 Jun 2017 11:35:01 -0700
Subject: MIPS: Fix bnezc/jialc return address calculation
From: Paul Burton <paul.burton@xxxxxxxxxx>
commit 1a73d9310e093fc3adffba4d0a67b9fab2ee3f63 upstream.
The code handling the pop76 opcode (ie. bnezc & jialc instructions) in
__compute_return_epc_for_insn() needs to set the value of $31 in the
jialc case, which is encoded with rs = 0. However its check to
differentiate bnezc (rs != 0) from jialc (rs = 0) was unfortunately
backwards, meaning that if we emulate a bnezc instruction we clobber $31
& if we emulate a jialc instruction it actually behaves like a jic
instruction.
Fix this by inverting the check of rs to match the way the instructions
are actually encoded.
Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
Fixes: 28d6f93d201d ("MIPS: Emulate the new MIPS R6 BNEZC and JIALC instructions")
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/16178/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/mips/kernel/branch.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -816,8 +816,10 @@ int __compute_return_epc_for_insn(struct
break;
}
/* Compact branch: BNEZC || JIALC */
- if (insn.i_format.rs)
+ if (!insn.i_format.rs) {
+ /* JIALC: set $31/ra */
regs->regs[31] = epc + 4;
+ }
regs->cp0_epc += 8;
break;
#endif
Patches currently in stable-queue which might be from paul.burton@xxxxxxxxxx are
queue-4.4/mips-fix-bnezc-jialc-return-address-calculation.patch