[3.13.y.z extended stable] Patch "MIPS: mcount: Adjust stack pointer for static trace in MIPS32" has been added to staging queue

[Kamal Mostafa]

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

MIPS: mcount: Adjust stack pointer for static trace in MIPS32

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree
which can be found at:

http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.9.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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From bc05a18c42ba643c38bfc4059cbc3d8772a98c4f Mon Sep 17 00:00:00 2001

From: Markos Chandras <***@imgtec.com>
Date: Tue, 16 Sep 2014 15:55:12 +0100
Subject: MIPS: mcount: Adjust stack pointer for static trace in MIPS32

commit 8a574cfa2652545eb95595d38ac2a0bb501af0ae upstream.

Every mcount() call in the MIPS 32-bit kernel is done as follows:

[...]
move at, ra
jal _mcount
addiu sp, sp, -8
[...]

but upon returning from the mcount() function, the stack pointer
is not adjusted properly. This is explained in details in 58b69401c797
(MIPS: Function tracer: Fix broken function tracing).

Commit ad8c396936e3 ("MIPS: Unbreak function tracer for 64-bit kernel.)
fixed the stack manipulation for 64-bit but it didn't fix it completely
for MIPS32.

Signed-off-by: Markos Chandras <***@imgtec.com>
Cc: linux-***@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7792/
Signed-off-by: Ralf Baechle <***@linux-mips.org>
Signed-off-by: Kamal Mostafa <***@canonical.com>
---
arch/mips/kernel/mcount.S | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 539b629..8f89ff4 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -123,7 +123,11 @@ NESTED(_mcount, PT_SIZE, ra)
nop
#endif
b ftrace_stub
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#else
nop
+#endif

static_trace:
MCOUNT_SAVE_REGS
@@ -133,6 +137,9 @@ static_trace:
move a1, AT /* arg2: parent's return address */

MCOUNT_RESTORE_REGS
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#endif
.globl ftrace_stub
ftrace_stub:
RETURN_BACK
@@ -177,6 +184,11 @@ NESTED(ftrace_graph_caller, PT_SIZE, ra)
jal prepare_ftrace_return
nop
MCOUNT_RESTORE_REGS
+#ifndef CONFIG_DYNAMIC_FTRACE
+#ifdef CONFIG_32BIT
+ addiu sp, sp, 8
+#endif
+#endif
RETURN_BACK
END(ftrace_graph_caller)

--
1.9.1