4 files changed, 43 insertions, 10 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 3d727a8a23bc..0a2ba51cf35d 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -272,7 +272,15 @@ __und_svc:
 	@
 	@  r0 - instruction
 	@
+#ifndef	CONFIG_THUMB2_KERNEL
 	ldr	r0, [r2, #-4]
+#else
+	ldrh	r0, [r2, #-2]			@ Thumb instruction at LR - 2
+	and	r9, r0, #0xf800
+	cmp	r9, #0xe800			@ 32-bit instruction if xx >= 0
+	ldrhhs	r9, [r2]			@ bottom 16 bits
+	orrhs	r0, r9, r0, lsl #16
+#endif
 	adr	r9, BSYM(1f)
 	bl	call_fpe
 
@@ -678,7 +686,9 @@ ENTRY(fp_enter)
 	.word	no_fp
 	.previous
 
-no_fp:	mov	pc, lr
+ENTRY(no_fp)
+	mov	pc, lr
+ENDPROC(no_fp)
 
 __und_usr_unknown:
 	enable_irq
@@ -734,13 +744,6 @@ ENTRY(__switch_to)
 #ifdef CONFIG_MMU
 	ldr	r6, [r2, #TI_CPU_DOMAIN]
 #endif
-#if __LINUX_ARM_ARCH__ >= 6
-#ifdef CONFIG_CPU_32v6K
-	clrex
-#else
-	strex	r5, r4, [ip]			@ Clear exclusive monitor
-#endif
-#endif
 #if defined(CONFIG_HAS_TLS_REG)
 	mcr	p15, 0, r3, c13, c0, 3		@ set TLS register
 #elif !defined(CONFIG_TLS_REG_EMUL)
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index a4eaf4f920c5..e17e3c30d957 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -76,13 +76,25 @@
 #ifndef CONFIG_THUMB2_KERNEL
 	.macro	svc_exit, rpsr
 	msr	spsr_cxsf, \rpsr
+#if defined(CONFIG_CPU_32v6K)
+	clrex					@ clear the exclusive monitor
 	ldmia	sp, {r0 - pc}^			@ load r0 - pc, cpsr
+#elif defined (CONFIG_CPU_V6)
+	ldr	r0, [sp]
+	strex	r1, r2, [sp]			@ clear the exclusive monitor
+	ldmib	sp, {r1 - pc}^			@ load r1 - pc, cpsr
+#endif
 	.endm
 
 	.macro	restore_user_regs, fast = 0, offset = 0
 	ldr	r1, [sp, #\offset + S_PSR]	@ get calling cpsr
 	ldr	lr, [sp, #\offset + S_PC]!	@ get pc
 	msr	spsr_cxsf, r1			@ save in spsr_svc
+#if defined(CONFIG_CPU_32v6K)
+	clrex					@ clear the exclusive monitor
+#elif defined (CONFIG_CPU_V6)
+	strex	r1, r2, [sp]			@ clear the exclusive monitor
+#endif
 	.if	\fast
 	ldmdb	sp, {r1 - lr}^			@ get calling r1 - lr
 	.else
@@ -98,6 +110,7 @@
 	.endm
 #else	/* CONFIG_THUMB2_KERNEL */
 	.macro	svc_exit, rpsr
+	clrex					@ clear the exclusive monitor
 	ldr	r0, [sp, #S_SP]			@ top of the stack
 	ldr	r1, [sp, #S_PC]			@ return address
 	tst	r0, #4				@ orig stack 8-byte aligned?
@@ -110,6 +123,7 @@
 	.endm
 
 	.macro	restore_user_regs, fast = 0, offset = 0
+	clrex					@ clear the exclusive monitor
 	mov	r2, sp
 	load_user_sp_lr r2, r3, \offset + S_SP	@ calling sp, lr
 	ldr	r1, [sp, #\offset + S_PSR]	@ get calling cpsr
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c
index f692efddd449..60c62c377fa9 100644
--- a/arch/arm/kernel/kprobes.c
+++ b/arch/arm/kernel/kprobes.c
@@ -22,6 +22,7 @@
 #include <linux/kernel.h>
 #include <linux/kprobes.h>
 #include <linux/module.h>
+#include <linux/stop_machine.h>
 #include <linux/stringify.h>
 #include <asm/traps.h>
 #include <asm/cacheflush.h>
@@ -83,10 +84,24 @@ void __kprobes arch_arm_kprobe(struct kprobe *p)
 	flush_insns(p->addr, 1);
 }
 
+/*
+ * The actual disarming is done here on each CPU and synchronized using
+ * stop_machine. This synchronization is necessary on SMP to avoid removing
+ * a probe between the moment the 'Undefined Instruction' exception is raised
+ * and the moment the exception handler reads the faulting instruction from
+ * memory.
+ */
+int __kprobes __arch_disarm_kprobe(void *p)
+{
+	struct kprobe *kp = p;
+	*kp->addr = kp->opcode;
+	flush_insns(kp->addr, 1);
+	return 0;
+}
+
 void __kprobes arch_disarm_kprobe(struct kprobe *p)
 {
-	*p->addr = p->opcode;
-	flush_insns(p->addr, 1);
+	stop_machine(__arch_disarm_kprobe, p, &cpu_online_map);
 }
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
index 39d3ffb9ff2b..aecf87dfbaec 100644
--- a/arch/arm/kernel/vmlinux.lds.S
+++ b/arch/arm/kernel/vmlinux.lds.S
@@ -83,6 +83,7 @@ SECTIONS
 		EXIT_TEXT
 		EXIT_DATA
 		*(.exitcall.exit)
+		*(.discard)
 		*(.ARM.exidx.exit.text)
 		*(.ARM.extab.exit.text)
 #ifndef CONFIG_HOTPLUG_CPU