Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

Pull ARM updates from Russell King:

 - add arch/arm/Kbuild from Masahiro Yamada.

 - simplify act_mm macro, since it contains an open-coded
   get_thread_info.

 - VFP updates for Clang from Stefan Agner.

 - Fix unwinder for Clang from Nathan Huckleberry.

 - Remove unused it8152 PCI host controller, used by the removed cm-x2xx
   platforms from Mike Rapoport.

 - Further explanation of __range_ok().

 - Remove kimage_voffset that isn't used anymore from Marc Zyngier.

 - Drop ancient Thumb-2 workaround for old binutils from Ard Biesheuvel.

 - Documentation cleanup for mach-* from Pete Zaitcev.

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8996/1: Documentation/Clean up the description of mach-<class>
  ARM: 8995/1: drop Thumb-2 workaround for ancient binutils
  ARM: 8994/1: mm: drop kimage_voffset which was only used by KVM
  ARM: uaccess: add further explanation of __range_ok()
  ARM: 8993/1: remove it8152 PCI controller driver
  ARM: 8992/1: Fix unwind_frame for clang-built kernels
  ARM: 8991/1: use VFP assembler mnemonics if available
  ARM: 8990/1: use VFP assembler mnemonics in register load/store macros
  ARM: 8989/1: use .fpu assembler directives instead of assembler arguments
  ARM: 8982/1: mm: Simplify act_mm macro
  ARM: 8981/1: add arch/arm/Kbuild

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
index cc726afea023..76ea4178a55c 100644
--- a/arch/arm/kernel/stacktrace.c
+++ b/arch/arm/kernel/stacktrace.c
@@ -22,6 +22,19 @@
  * A simple function epilogue looks like this:
  *	ldm	sp, {fp, sp, pc}
  *
+ * When compiled with clang, pc and sp are not pushed. A simple function
+ * prologue looks like this when built with clang:
+ *
+ *	stmdb	{..., fp, lr}
+ *	add	fp, sp, #x
+ *	sub	sp, sp, #y
+ *
+ * A simple function epilogue looks like this when built with clang:
+ *
+ *	sub	sp, fp, #x
+ *	ldm	{..., fp, pc}
+ *
+ *
  * Note that with framepointer enabled, even the leaf functions have the same
  * prologue and epilogue, therefore we can ignore the LR value in this case.
  */
@@ -34,6 +47,16 @@ int notrace unwind_frame(struct stackframe *frame)
 	low = frame->sp;
 	high = ALIGN(low, THREAD_SIZE);
 
+#ifdef CONFIG_CC_IS_CLANG
+	/* check current frame pointer is within bounds */
+	if (fp < low + 4 || fp > high - 4)
+		return -EINVAL;
+
+	frame->sp = frame->fp;
+	frame->fp = *(unsigned long *)(fp);
+	frame->pc = frame->lr;
+	frame->lr = *(unsigned long *)(fp + 4);
+#else
 	/* check current frame pointer is within bounds */
 	if (fp < low + 12 || fp > high - 4)
 		return -EINVAL;
@@ -42,6 +65,7 @@ int notrace unwind_frame(struct stackframe *frame)
 	frame->fp = *(unsigned long *)(fp - 12);
 	frame->sp = *(unsigned long *)(fp - 8);
 	frame->pc = *(unsigned long *)(fp - 4);
+#endif
 
 	return 0;
 }