1 files changed, 21 insertions, 29 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index d073d981a730..50ea0ac8c9bf 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -21,8 +21,7 @@
 #include <asm/nops.h>
 
 
-/* Long is fine, even if it is only 4 bytes ;-) */
-static unsigned long *ftrace_nop;
+static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
 
 union ftrace_code_union {
         char code[MCOUNT_INSN_SIZE];
@@ -33,17 +32,17 @@ union ftrace_code_union {
 };
 
 
-static int notrace ftrace_calc_offset(long ip, long addr)
+static int ftrace_calc_offset(long ip, long addr)
 {
         return (int)(addr - ip);
 }
 
-notrace unsigned char *ftrace_nop_replace(void)
+unsigned char *ftrace_nop_replace(void)
 {
-        return (char *)ftrace_nop;
+        return ftrace_nop;
 }
 
-notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
         static union ftrace_code_union calc;
 
@@ -57,7 +56,7 @@ notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
         return calc.code;
 }
 
-notrace int
+int
 ftrace_modify_code(unsigned long ip, unsigned char *old_code,
                    unsigned char *new_code)
 {
@@ -66,26 +65,31 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
         /*
          * Note: Due to modules and __init, code can
          *  disappear and change, we need to protect against faulting
-         *  as well as code changing.
+         *  as well as code changing. We do this by using the
+         *  probe_kernel_* functions.
          *
          * No real locking needed, this code is run through
          * kstop_machine, or before SMP starts.
          */
-        if (__copy_from_user_inatomic(replaced, (char __user *)ip, MCOUNT_INSN_SIZE))
-                return 1;
 
+        /* read the text we want to modify */
+        if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+                return -EFAULT;
+
+        /* Make sure it is what we expect it to be */
         if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
-                return 2;
+                return -EINVAL;
 
-        WARN_ON_ONCE(__copy_to_user_inatomic((char __user *)ip, new_code,
-                                    MCOUNT_INSN_SIZE));
+        /* replace the text with the new text */
+        if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
+                return -EPERM;
 
         sync_core();
 
         return 0;
 }
 
-notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+int ftrace_update_ftrace_func(ftrace_func_t func)
 {
         unsigned long ip = (unsigned long)(&ftrace_call);
         unsigned char old[MCOUNT_INSN_SIZE], *new;
@@ -98,13 +102,6 @@ notrace int ftrace_update_ftrace_func(ftrace_func_t func)
         return ret;
 }
 
-notrace int ftrace_mcount_set(unsigned long *data)
-{
-        /* mcount is initialized as a nop */
-        *data = 0;
-        return 0;
-}
-
 int __init ftrace_dyn_arch_init(void *data)
 {
         extern const unsigned char ftrace_test_p6nop[];
@@ -127,9 +124,6 @@ int __init ftrace_dyn_arch_init(void *data)
          * TODO: check the cpuid to determine the best nop.
          */
         asm volatile (
-                "jmp ftrace_test_jmp\n"
-                /* This code needs to stay around */
-                ".section .text, \"ax\"\n"
                 "ftrace_test_jmp:"
                 "jmp ftrace_test_p6nop\n"
                 "nop\n"
@@ -140,8 +134,6 @@ int __init ftrace_dyn_arch_init(void *data)
                 "jmp 1f\n"
                 "ftrace_test_nop5:"
                 ".byte 0x66,0x66,0x66,0x66,0x90\n"
-                "jmp 1f\n"
-                ".previous\n"
                 "1:"
                 ".section .fixup, \"ax\"\n"
                 "2:     movl $1, %0\n"
@@ -156,15 +148,15 @@ int __init ftrace_dyn_arch_init(void *data)
         switch (faulted) {
         case 0:
                 pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
-                ftrace_nop = (unsigned long *)ftrace_test_p6nop;
+                memcpy(ftrace_nop, ftrace_test_p6nop, MCOUNT_INSN_SIZE);
                 break;
         case 1:
                 pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
-                ftrace_nop = (unsigned long *)ftrace_test_nop5;
+                memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
                 break;
         case 2:
                 pr_info("ftrace: converting mcount calls to jmp . + 5\n");
-                ftrace_nop = (unsigned long *)ftrace_test_jmp;
+                memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
                 break;
         }