[PATCH v2] ARM: unwind: add unwind directives to bitops assembly macros

[Will Deacon]

The bitops functions (e.g. _test_and_set_bit) on ARM do not have unwind
annotations and therefore the kernel cannot backtrace out of them on a
fatal error (for example, NULL pointer dereference).

This patch annotates the bitops assembly macros with UNWIND annotations
so that we can produce a meaningful backtrace on error. Callers of the
macros are modified to pass their function name as a macro parameter,
enforcing that the macros are used as standalone function implementations.

Cc: Dave Martin <dave.martin at linaro.org>
Signed-off-by: Will Deacon <will.deacon at arm.com>
---

v2: Added function name argument to bitops macros, as suggested by Dave.

 arch/arm/lib/bitops.h        |   26 ++++++++++++++++++++++----
 arch/arm/lib/changebit.S     |    4 +---
 arch/arm/lib/clearbit.S      |    4 +---
 arch/arm/lib/setbit.S        |    4 +---
 arch/arm/lib/testchangebit.S |    4 +---
 arch/arm/lib/testclearbit.S  |    4 +---
 arch/arm/lib/testsetbit.S    |    4 +---
 7 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/arch/arm/lib/bitops.h b/arch/arm/lib/bitops.h
index 10d868a..d6408d1 100644
--- a/arch/arm/lib/bitops.h
+++ b/arch/arm/lib/bitops.h
@@ -1,5 +1,9 @@
+#include <asm/unwind.h>
+
 #if __LINUX_ARM_ARCH__ >= 6
-	.macro	bitop, instr
+	.macro	bitop, name, instr
+ENTRY(	\name		)
+UNWIND(	.fnstart	)
 	ands	ip, r1, #3
 	strneb	r1, [ip]		@ assert word-aligned
 	mov	r2, #1
@@ -13,9 +17,13 @@
 	cmp	r0, #0
 	bne	1b
 	bx	lr
+UNWIND(	.fnend		)
+ENDPROC(\name		)
 	.endm
 
-	.macro	testop, instr, store
+	.macro	testop, name, instr, store
+ENTRY(	\name		)
+UNWIND(	.fnstart	)
 	ands	ip, r1, #3
 	strneb	r1, [ip]		@ assert word-aligned
 	mov	r2, #1
@@ -34,9 +42,13 @@
 	cmp	r0, #0
 	movne	r0, #1
 2:	bx	lr
+UNWIND(	.fnend		)
+ENDPROC(\name		)
 	.endm
 #else
-	.macro	bitop, instr
+	.macro	bitop, name, instr
+ENTRY(	\name		)
+UNWIND(	.fnstart	)
 	ands	ip, r1, #3
 	strneb	r1, [ip]		@ assert word-aligned
 	and	r2, r0, #31
@@ -49,6 +61,8 @@
 	str	r2, [r1, r0, lsl #2]
 	restore_irqs ip
 	mov	pc, lr
+UNWIND(	.fnend		)
+ENDPROC(\name		)
 	.endm
 
 /**
@@ -59,7 +73,9 @@
  * Note: we can trivially conditionalise the store instruction
  * to avoid dirtying the data cache.
  */
-	.macro	testop, instr, store
+	.macro	testop, name, instr, store
+ENTRY(	\name		)
+UNWIND(	.fnstart	)
 	ands	ip, r1, #3
 	strneb	r1, [ip]		@ assert word-aligned
 	and	r3, r0, #31
@@ -73,5 +89,7 @@
 	moveq	r0, #0
 	restore_irqs ip
 	mov	pc, lr
+UNWIND(	.fnend		)
+ENDPROC(\name		)
 	.endm
 #endif
diff --git a/arch/arm/lib/changebit.S b/arch/arm/lib/changebit.S
index 68ed5b6..f402786 100644
--- a/arch/arm/lib/changebit.S
+++ b/arch/arm/lib/changebit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
                 .text
 
-ENTRY(_change_bit)
-	bitop	eor
-ENDPROC(_change_bit)
+bitop	_change_bit, eor
diff --git a/arch/arm/lib/clearbit.S b/arch/arm/lib/clearbit.S
index 4c04c3b..f6b75fb 100644
--- a/arch/arm/lib/clearbit.S
+++ b/arch/arm/lib/clearbit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
                 .text
 
-ENTRY(_clear_bit)
-	bitop	bic
-ENDPROC(_clear_bit)
+bitop	_clear_bit, bic
diff --git a/arch/arm/lib/setbit.S b/arch/arm/lib/setbit.S
index bbee5c6..618feda 100644
--- a/arch/arm/lib/setbit.S
+++ b/arch/arm/lib/setbit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
 		.text
 
-ENTRY(_set_bit)
-	bitop	orr
-ENDPROC(_set_bit)
+bitop	_set_bit, orr
diff --git a/arch/arm/lib/testchangebit.S b/arch/arm/lib/testchangebit.S
index 15a4d43..4becdc3 100644
--- a/arch/arm/lib/testchangebit.S
+++ b/arch/arm/lib/testchangebit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
                 .text
 
-ENTRY(_test_and_change_bit)
-	testop	eor, str
-ENDPROC(_test_and_change_bit)
+testop	_test_and_change_bit, eor, str
diff --git a/arch/arm/lib/testclearbit.S b/arch/arm/lib/testclearbit.S
index 521b66b..918841d 100644
--- a/arch/arm/lib/testclearbit.S
+++ b/arch/arm/lib/testclearbit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
                 .text
 
-ENTRY(_test_and_clear_bit)
-	testop	bicne, strne
-ENDPROC(_test_and_clear_bit)
+testop	_test_and_clear_bit, bicne, strne
diff --git a/arch/arm/lib/testsetbit.S b/arch/arm/lib/testsetbit.S
index 1c98cc2..8d1b2fe 100644
--- a/arch/arm/lib/testsetbit.S
+++ b/arch/arm/lib/testsetbit.S
@@ -12,6 +12,4 @@
 #include "bitops.h"
                 .text
 
-ENTRY(_test_and_set_bit)
-	testop	orreq, streq
-ENDPROC(_test_and_set_bit)
+testop	_test_and_set_bit, orreq, streq
-- 
1.7.4.1