2 files changed, 43 insertions, 0 deletions

diff --git a/arch/arm/kernel/kprobes-common.c b/arch/arm/kernel/kprobes-common.c
index 32bb0f236684..a5394fb4e4e0 100644
--- a/arch/arm/kernel/kprobes-common.c
+++ b/arch/arm/kernel/kprobes-common.c
@@ -59,10 +59,25 @@ void __init test_load_write_pc_interworking(void)
 #endif /* !test_load_write_pc_interworking */
 
 
+#ifndef test_alu_write_pc_interworking
+
+bool alu_write_pc_interworks;
+
+void __init test_alu_write_pc_interworking(void)
+{
+        int arch = cpu_architecture();
+        BUG_ON(arch == CPU_ARCH_UNKNOWN);
+        alu_write_pc_interworks = arch >= CPU_ARCH_ARMv7;
+}
+
+#endif /* !test_alu_write_pc_interworking */
+
+
 void __init arm_kprobe_decode_init(void)
 {
         find_str_pc_offset();
         test_load_write_pc_interworking();
+        test_alu_write_pc_interworking();
 }
 
 
diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h
index c442852e65e4..a6aeda0a6c7f 100644
--- a/arch/arm/kernel/kprobes.h
+++ b/arch/arm/kernel/kprobes.h
@@ -133,6 +133,34 @@ static inline void __kprobes load_write_pc(long pcv, struct pt_regs *regs)
 }
 
 
+#if __LINUX_ARM_ARCH__ >= 7
+
+#define alu_write_pc_interworks true
+#define test_alu_write_pc_interworking()
+
+#elif __LINUX_ARM_ARCH__ <= 5
+
+/* Kernels built for <= ARMv5 should never run on >= ARMv6 hardware, so... */
+#define alu_write_pc_interworks false
+#define test_alu_write_pc_interworking()
+
+#else /* __LINUX_ARM_ARCH__ == 6 */
+
+/* We could be an ARMv6 binary on ARMv7 hardware so we need a run-time check. */
+extern bool alu_write_pc_interworks;
+void __init test_alu_write_pc_interworking(void);
+
+#endif /* __LINUX_ARM_ARCH__ == 6 */
+
+static inline void __kprobes alu_write_pc(long pcv, struct pt_regs *regs)
+{
+        if (alu_write_pc_interworks)
+                bx_write_pc(pcv, regs);
+        else
+                regs->ARM_pc = pcv;
+}
+
+
 void __kprobes kprobe_simulate_nop(struct kprobe *p, struct pt_regs *regs);
 void __kprobes kprobe_emulate_none(struct kprobe *p, struct pt_regs *regs);