This is a note to let you know that I've just added the patch titled
Revert "ARM64: unwind: Fix PC calculation"
to the 3.10-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-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9702970c7bd3e2d6fecb642a190269131d4ac16c Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@xxxxxxx>
Date: Wed, 28 Oct 2015 16:56:13 +0000
Subject: Revert "ARM64: unwind: Fix PC calculation"
From: Will Deacon <will.deacon@xxxxxxx>
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.
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 407991bf79f5..ccb6078ed9f2 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -48,11 +48,7 @@ int notrace unwind_frame(struct stackframe *frame)
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 will.deacon@xxxxxxx are
queue-3.10/revert-arm64-unwind-fix-pc-calculation.patch
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