Patch "Revert "ARM64: unwind: Fix PC calculation"" has been added to the 4.1-stable tree

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

Revert "ARM64: unwind: Fix PC calculation"

to the 4.1-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:
revert-arm64-unwind-fix-pc-calculation.patch
and it can be found in the queue-4.1 subdirectory.

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

From: Will Deacon <[email protected]>
Date: Wed, 28 Oct 2015 16:56:13 +0000
Subject: Revert "ARM64: unwind: Fix PC calculation"

From: Will Deacon <[email protected]>

commit 9702970c7bd3e2d6fecb642a190269131d4ac16c upstream.

This reverts commit e306dfd06fcb44d21c80acb8e5a88d55f3d1cf63.

With this patch applied, we were the only architecture making this sort of adjustment to the PC calculation in the unwinder. This causes problems for ftrace, where the PC values are matched against the contents of the stack frames in the callchain and fail to match any records after the address adjustment.

Whilst there has been some effort to change ftrace to workaround this, those patches are not yet ready for mainline and, since we're the odd architecture in this regard, let's just step in line with other architectures (like arch/arm/) for now.

---
 arch/arm64/kernel/stacktrace.c |    6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

@@ -48,11 +48,7 @@ int notrace unwind_frame(struct stackfra
 
 	frame->sp = fp + 0x10;
 	frame->fp = *(unsigned long *)(fp);
-	/*
-	 * -4 here because we care about the PC at time of bl,
-	 * not where the return will go.
-	 */
-	frame->pc = *(unsigned long *)(fp + 8) - 4;
+	frame->pc = *(unsigned long *)(fp + 8);
 
 	return 0;
 }

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

queue-4.1/revert-arm64-unwind-fix-pc-calculation.patch