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Date: Tue, 25 Nov 2014 20:23:07 +0800
From: Lin Yongting <linyongting@...il.com>
To: linux@....linux.org.uk, victor.kamensky@...aro.org,
nico@...aro.org, linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, linyongting@...il.com,
linyongting@...wei.com
Subject: [PATCH] ARM: Add unwinding support for memory copy functions
The memory copy functions(memcpy, __copy_from_user, __copy_to_user)
never had unwinding annotations added. Currently, when accessing
invalid pointer by these functions occurs the backtrace shown will
stop at these functions or some completely unrelated function.
Add unwinding annotations in hopes of getting a more useful backtrace
in following cases:
1. die on accessing invalid pointer by these functions
2. kprobe trapped at any instruction within these functions
3. interrupted at any instruction within these functions
Signed-off-by: Lin Yongting <linyongting@...il.com>
---
arch/arm/lib/copy_from_user.S | 5 +++++
arch/arm/lib/copy_template.S | 30 ++++++++++++++++++++++++++++++
arch/arm/lib/copy_to_user.S | 5 +++++
arch/arm/lib/memcpy.S | 5 +++++
4 files changed, 45 insertions(+)
diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S
index 66a477a..7a235b9 100644
--- a/arch/arm/lib/copy_from_user.S
+++ b/arch/arm/lib/copy_from_user.S
@@ -12,6 +12,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/unwind.h>
/*
* Prototype:
@@ -77,6 +78,10 @@
stmdb sp!, {r0, r2, r3, \reg1, \reg2}
.endm
+ .macro usave reg1 reg2
+ UNWIND( .save {r0, r2, r3, \reg1, \reg2} )
+ .endm
+
.macro exit reg1 reg2
add sp, sp, #8
ldmfd sp!, {r0, \reg1, \reg2}
diff --git a/arch/arm/lib/copy_template.S b/arch/arm/lib/copy_template.S
index 3bc8eb8..652e4d9 100644
--- a/arch/arm/lib/copy_template.S
+++ b/arch/arm/lib/copy_template.S
@@ -53,6 +53,12 @@
* data as needed by the implementation including this code. Called
* upon code entry.
*
+ * usave reg1 reg2
+ *
+ * Unwind annotation macro is corresponding for 'enter' macro.
+ * It tell unwinder that preserved some provided registers on the stack
+ * and additional data by a prior 'enter' macro.
+ *
* exit reg1 reg2
*
* Restore registers with the values previously saved with the
@@ -67,7 +73,12 @@
*/
+ UNWIND( .fnstart )
enter r4, lr
+ UNWIND( .fnend )
+
+ UNWIND( .fnstart )
+ usave r4, lr @ in first stmdb block
subs r2, r2, #4
blt 8f
@@ -79,6 +90,11 @@
1: subs r2, r2, #(28)
stmfd sp!, {r5 - r8}
+ UNWIND( .fnend )
+
+ UNWIND( .fnstart )
+ usave r4, lr
+ UNWIND( .save {r5 - r8} ) @ in second stmfd block
blt 5f
CALGN( ands ip, r0, #31 )
@@ -144,7 +160,10 @@
CALGN( bcs 2b )
7: ldmfd sp!, {r5 - r8}
+ UNWIND( .fnend ) @ end of second stmfd block
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
8: movs r2, r2, lsl #31
ldr1b r1, r3, ne, abort=21f
ldr1b r1, r4, cs, abort=21f
@@ -173,10 +192,13 @@
ldr1w r1, lr, abort=21f
beq 17f
bgt 18f
+ UNWIND( .fnend )
.macro forward_copy_shift pull push
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
subs r2, r2, #28
blt 14f
@@ -187,7 +209,11 @@
CALGN( bcc 15f )
11: stmfd sp!, {r5 - r9}
+ UNWIND( .fnend )
+ UNWIND( .fnstart )
+ usave r4, lr
+ UNWIND( .save {r5 - r9} ) @ in new second stmfd block
PLD( pld [r1, #0] )
PLD( subs r2, r2, #96 )
PLD( pld [r1, #28] )
@@ -221,7 +247,10 @@
PLD( bge 13b )
ldmfd sp!, {r5 - r9}
+ UNWIND( .fnend ) @ end of the second stmfd block
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
14: ands ip, r2, #28
beq 16f
@@ -236,6 +265,7 @@
16: sub r1, r1, #(\push / 8)
b 8b
+ UNWIND( .fnend )
.endm
diff --git a/arch/arm/lib/copy_to_user.S b/arch/arm/lib/copy_to_user.S
index d066df6..a9d3db1 100644
--- a/arch/arm/lib/copy_to_user.S
+++ b/arch/arm/lib/copy_to_user.S
@@ -12,6 +12,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/unwind.h>
/*
* Prototype:
@@ -80,6 +81,10 @@
stmdb sp!, {r0, r2, r3, \reg1, \reg2}
.endm
+ .macro usave reg1 reg2
+ UNWIND( .save {r0, r2, r3, \reg1, \reg2} )
+ .endm
+
.macro exit reg1 reg2
add sp, sp, #8
ldmfd sp!, {r0, \reg1, \reg2}
diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index a9b9e22..7797e81 100644
--- a/arch/arm/lib/memcpy.S
+++ b/arch/arm/lib/memcpy.S
@@ -12,6 +12,7 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/unwind.h>
#define LDR1W_SHIFT 0
#define STR1W_SHIFT 0
@@ -48,6 +49,10 @@
stmdb sp!, {r0, \reg1, \reg2}
.endm
+ .macro usave reg1 reg2
+ UNWIND( .save {r0, \reg1, \reg2} )
+ .endm
+
.macro exit reg1 reg2
ldmfd sp!, {r0, \reg1, \reg2}
.endm
--
1.7.9.5
--
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