4 files changed, 87 insertions, 59 deletions

diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 43b740d0e374..dd3d5f16c147 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -7,6 +7,7 @@ AFLAGS_head.o        := -DTEXT_OFFSET=$(TEXT_OFFSET)
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_ftrace.o = -pg
+CFLAGS_REMOVE_insn.o = -pg
 endif
 
 CFLAGS_REMOVE_return_address.o = -pg
@@ -34,8 +35,8 @@ obj-$(CONFIG_HAVE_SCHED_CLOCK)	+= sched_clock.o
 obj-$(CONFIG_SMP)               += smp.o smp_tlb.o
 obj-$(CONFIG_HAVE_ARM_SCU)      += smp_scu.o
 obj-$(CONFIG_HAVE_ARM_TWD)      += smp_twd.o
-obj-$(CONFIG_DYNAMIC_FTRACE)    += ftrace.o
-obj-$(CONFIG_FUNCTION_GRAPH_TRACER)     += ftrace.o
+obj-$(CONFIG_DYNAMIC_FTRACE)    += ftrace.o insn.o
+obj-$(CONFIG_FUNCTION_GRAPH_TRACER)     += ftrace.o insn.o
 obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_KPROBES)           += kprobes.o kprobes-common.o
 ifdef CONFIG_THUMB2_KERNEL
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 5c9cecfaeb21..df0bf0c8cb79 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -19,6 +19,8 @@
 #include <asm/opcodes.h>
 #include <asm/ftrace.h>
 
+#include "insn.h"
+
 #ifdef CONFIG_THUMB2_KERNEL
 #define NOP             0xf85deb04      /* pop.w {lr} */
 #else
@@ -61,64 +63,9 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
 }
 #endif
 
-#ifdef CONFIG_THUMB2_KERNEL
-static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
-                                       bool link)
-{
-        unsigned long s, j1, j2, i1, i2, imm10, imm11;
-        unsigned long first, second;
-        long offset;
-
-        offset = (long)addr - (long)(pc + 4);
-        if (offset < -16777216 || offset > 16777214) {
-                WARN_ON_ONCE(1);
-                return 0;
-        }
-
-        s       = (offset >> 24) & 0x1;
-        i1      = (offset >> 23) & 0x1;
-        i2      = (offset >> 22) & 0x1;
-        imm10   = (offset >> 12) & 0x3ff;
-        imm11   = (offset >>  1) & 0x7ff;
-
-        j1 = (!i1) ^ s;
-        j2 = (!i2) ^ s;
-
-        first = 0xf000 | (s << 10) | imm10;
-        second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
-        if (link)
-                second |= 1 << 14;
-
-        return __opcode_thumb32_compose(first, second);
-}
-#else
-static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
-                                       bool link)
-{
-        unsigned long opcode = 0xea000000;
-        long offset;
-
-        if (link)
-                opcode |= 1 << 24;
-
-        offset = (long)addr - (long)(pc + 8);
-        if (unlikely(offset < -33554432 || offset > 33554428)) {
-                /* Can't generate branches that far (from ARM ARM). Ftrace
-                 * doesn't generate branches outside of kernel text.
-                 */
-                WARN_ON_ONCE(1);
-                return 0;
-        }
-
-        offset = (offset >> 2) & 0x00ffffff;
-
-        return opcode | offset;
-}
-#endif
-
 static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
 {
-        return ftrace_gen_branch(pc, addr, true);
+        return arm_gen_branch_link(pc, addr);
 }
 
 static int ftrace_modify_code(unsigned long pc, unsigned long old,
@@ -258,7 +205,7 @@ static int __ftrace_modify_caller(unsigned long *callsite,
 {
         unsigned long caller_fn = (unsigned long) func;
         unsigned long pc = (unsigned long) callsite;
-        unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
+        unsigned long branch = arm_gen_branch(pc, caller_fn);
         unsigned long nop = 0xe1a00000; /* mov r0, r0 */
         unsigned long old = enable ? nop : branch;
         unsigned long new = enable ? branch : nop;
diff --git a/arch/arm/kernel/insn.c b/arch/arm/kernel/insn.c
new file mode 100644
index 000000000000..ab312e516546
--- /dev/null
+++ b/arch/arm/kernel/insn.c
@@ -0,0 +1,61 @@
+#include <linux/kernel.h>
+#include <asm/opcodes.h>
+
+static unsigned long
+__arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
+{
+        unsigned long s, j1, j2, i1, i2, imm10, imm11;
+        unsigned long first, second;
+        long offset;
+
+        offset = (long)addr - (long)(pc + 4);
+        if (offset < -16777216 || offset > 16777214) {
+                WARN_ON_ONCE(1);
+                return 0;
+        }
+
+        s       = (offset >> 24) & 0x1;
+        i1      = (offset >> 23) & 0x1;
+        i2      = (offset >> 22) & 0x1;
+        imm10   = (offset >> 12) & 0x3ff;
+        imm11   = (offset >>  1) & 0x7ff;
+
+        j1 = (!i1) ^ s;
+        j2 = (!i2) ^ s;
+
+        first = 0xf000 | (s << 10) | imm10;
+        second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
+        if (link)
+                second |= 1 << 14;
+
+        return __opcode_thumb32_compose(first, second);
+}
+
+static unsigned long
+__arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
+{
+        unsigned long opcode = 0xea000000;
+        long offset;
+
+        if (link)
+                opcode |= 1 << 24;
+
+        offset = (long)addr - (long)(pc + 8);
+        if (unlikely(offset < -33554432 || offset > 33554428)) {
+                WARN_ON_ONCE(1);
+                return 0;
+        }
+
+        offset = (offset >> 2) & 0x00ffffff;
+
+        return opcode | offset;
+}
+
+unsigned long
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link)
+{
+        if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
+                return __arm_gen_branch_thumb2(pc, addr, link);
+        else
+                return __arm_gen_branch_arm(pc, addr, link);
+}
diff --git a/arch/arm/kernel/insn.h b/arch/arm/kernel/insn.h
new file mode 100644
index 000000000000..994d60fd3ff5
--- /dev/null
+++ b/arch/arm/kernel/insn.h
@@ -0,0 +1,19 @@
+#ifndef __ASM_ARM_INSN_H
+#define __ASM_ARM_INSN_H
+
+unsigned long
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
+
+static inline unsigned long
+arm_gen_branch(unsigned long pc, unsigned long addr)
+{
+        return __arm_gen_branch(pc, addr, false);
+}
+
+static inline unsigned long
+arm_gen_branch_link(unsigned long pc, unsigned long addr)
+{
+        return __arm_gen_branch(pc, addr, true);
+}
+
+#endif