Patch "MIPS: End asm function prologue macros with .insn" has been added to the 3.18-stable tree

This is a note to let you know that I've just added the patch titled

MIPS: End asm function prologue macros with .insn

to the 3.18-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-end-asm-function-prologue-macros-with-.insn.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Paul Burton <[email protected]>
Date: Mon, 7 Nov 2016 11:14:09 +0000
Subject: MIPS: End asm function prologue macros with .insn

From: Paul Burton <[email protected]>

[ Upstream commit 08889582b8aa0bbc01a1e5a0033b9f98d2e11caa ]

When building a kernel targeting a microMIPS ISA, recent GNU linkers will fail the link if they cannot determine that the target of a branch or jump is microMIPS code, with errors such as the following:

mips-img-linux-gnu-ld: arch/mips/built-in.o: .text+0x542c:
Unsupported jump between ISA modes; consider recompiling with interlinking enabled.
mips-img-linux-gnu-ld: final link failed: Bad value

or:

./arch/mips/include/asm/uaccess.h:1017: warning: JALX to a non-word-aligned address

Placing anything other than an instruction at the start of a function written in assembly appears to trigger such errors. In order to prepare for allowing us to follow function prologue macros with an EXPORT_SYMBOL invocation, end the prologue macros (LEAD, NESTED & FEXPORT) with a .insn directive. This ensures that the start of the function is marked as code, which always makes sense for functions & safely prevents us from hitting the link errors described above.

Patchwork: https://patchwork.linux-mips.org/patch/14508/

---
 arch/mips/include/asm/asm.h |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

@@ -54,7 +54,8 @@
 		.align	2;				\
 		.type	symbol, @function;		\
 		.ent	symbol, 0;			\
-symbol:		.frame	sp, 0, ra
+symbol:		.frame	sp, 0, ra;			\
+		.insn
 
 /*
  * NESTED - declare nested routine entry point

@@ -63,8 +64,9 @@ symbol:		.frame	sp, 0, ra
 		.globl	symbol;				\
 		.align	2;				\
 		.type	symbol, @function;		\
-		.ent	symbol, 0;			 \
-symbol:		.frame	sp, framesize, rpc
+		.ent	symbol, 0;			\
+symbol:		.frame	sp, framesize, rpc;		\
+		.insn
 
 /*
  * END - mark end of function

@@ -86,7 +88,7 @@ symbol:
 #define FEXPORT(symbol)					\
 		.globl	symbol;				\
 		.type	symbol, @function;		\
-symbol:
+symbol:		.insn
 
 /*
  * ABS - export absolute symbol

Patches currently in stable-queue which might be from [email protected] are

queue-3.18/mips-netlogic-exclude-netlogic-xlp-pic-code-from-xlr-builds.patch queue-3.18/mips-end-asm-function-prologue-macros-with-.insn.patch