Patch "powerpc/64: Fix flush_(d|i)cache_range() called from modules" has been added to the 4.4-stable tree

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

powerpc/64: Fix flush_(d|i)cache_range() called from modules

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:
powerpc-64-fix-flush_-d-i-cache_range-called-from-modules.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 <[email protected]> know about it.

From: Oliver O'Halloran <[email protected]>
Date: Mon, 3 Apr 2017 13:25:12 +1000
Subject: powerpc/64: Fix flush_(d|i)cache_range() called from modules

From: Oliver O'Halloran <[email protected]>

commit 8f5f525d5b83f7d76a6baf9c4e94d4bf312ea7f6 upstream.

When the kernel is compiled to use 64bit ABIv2 the _GLOBAL() macro does not include a global entry point. A function's global entry point is used when the function is called from a different TOC context and in the kernel this typically means a call from a module into the vmlinux (or vice-versa).

There are a few exported asm functions declared with _GLOBAL() and calling them from a module will likely crash the kernel since any TOC relative load will yield garbage.

flush_icache_range() and flush_dcache_range() are both exported to modules, and use the TOC, so must use _GLOBAL_TOC().

---
 arch/powerpc/kernel/misc_64.S |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -67,6 +67,9 @@ PPC64_CACHES:
  */
 
 _KPROBE(flush_icache_range)
+0:	addis	r2,r12,(.TOC. - 0b)@ha
+	addi	r2, r2,(.TOC. - 0b)@l
+	.localentry flush_icache_range, . - flush_icache_range
 BEGIN_FTR_SECTION
 	PURGE_PREFETCHED_INS
 	blr

@@ -117,7 +120,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_I
  *
  *    flush all bytes from start to stop-1 inclusive
  */
-_GLOBAL(flush_dcache_range)
+_GLOBAL_TOC(flush_dcache_range)
 
 /*
  * Flush the data cache to memory 

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

queue-4.4/powerpc-64-fix-flush_-d-i-cache_range-called-from-modules.patch