1 files changed, 28 insertions, 72 deletions

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index c0062ad1e847..df0bf0c8cb79 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -16,10 +16,13 @@
 #include <linux/uaccess.h>
 
 #include <asm/cacheflush.h>
+#include <asm/opcodes.h>
 #include <asm/ftrace.h>
 
+#include "insn.h"
+
 #ifdef CONFIG_THUMB2_KERNEL
-#define NOP             0xeb04f85d      /* pop.w {lr} */
+#define NOP             0xf85deb04      /* pop.w {lr} */
 #else
 #define NOP             0xe8bd4000      /* pop {lr} */
 #endif
@@ -60,76 +63,31 @@ 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 (second << 16) | first;
-}
-#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,
-                              unsigned long new)
+                              unsigned long new, bool validate)
 {
         unsigned long replaced;
 
-        if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
-                return -EFAULT;
+        if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
+                old = __opcode_to_mem_thumb32(old);
+                new = __opcode_to_mem_thumb32(new);
+        } else {
+                old = __opcode_to_mem_arm(old);
+                new = __opcode_to_mem_arm(new);
+        }
 
-        if (replaced != old)
-                return -EINVAL;
+        if (validate) {
+                if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
+                        return -EFAULT;
+
+                if (replaced != old)
+                        return -EINVAL;
+        }
 
         if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
                 return -EPERM;
@@ -141,23 +99,21 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 
 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
-        unsigned long pc, old;
+        unsigned long pc;
         unsigned long new;
         int ret;
 
         pc = (unsigned long)&ftrace_call;
-        memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
         new = ftrace_call_replace(pc, (unsigned long)func);
 
-        ret = ftrace_modify_code(pc, old, new);
+        ret = ftrace_modify_code(pc, 0, new, false);
 
 #ifdef CONFIG_OLD_MCOUNT
         if (!ret) {
                 pc = (unsigned long)&ftrace_call_old;
-                memcpy(&old, &ftrace_call_old, MCOUNT_INSN_SIZE);
                 new = ftrace_call_replace(pc, (unsigned long)func);
 
-                ret = ftrace_modify_code(pc, old, new);
+                ret = ftrace_modify_code(pc, 0, new, false);
         }
 #endif
 
@@ -172,7 +128,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
         old = ftrace_nop_replace(rec);
         new = ftrace_call_replace(ip, adjust_address(rec, addr));
 
-        return ftrace_modify_code(rec->ip, old, new);
+        return ftrace_modify_code(rec->ip, old, new, true);
 }
 
 int ftrace_make_nop(struct module *mod,
@@ -185,7 +141,7 @@ int ftrace_make_nop(struct module *mod,
 
         old = ftrace_call_replace(ip, adjust_address(rec, addr));
         new = ftrace_nop_replace(rec);
-        ret = ftrace_modify_code(ip, old, new);
+        ret = ftrace_modify_code(ip, old, new, true);
 
 #ifdef CONFIG_OLD_MCOUNT
         if (ret == -EINVAL && addr == MCOUNT_ADDR) {
@@ -193,7 +149,7 @@ int ftrace_make_nop(struct module *mod,
 
                 old = ftrace_call_replace(ip, adjust_address(rec, addr));
                 new = ftrace_nop_replace(rec);
-                ret = ftrace_modify_code(ip, old, new);
+                ret = ftrace_modify_code(ip, old, new, true);
         }
 #endif
 
@@ -249,12 +205,12 @@ 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;
 
-        return ftrace_modify_code(pc, old, new);
+        return ftrace_modify_code(pc, old, new, true);
 }
 
 static int ftrace_modify_graph_caller(bool enable)