Merge git://git.infradead.org/mtd-2.6

[linux-2.6-omap-h63xx.git] / arch / x86 / kernel / ftrace.c

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 4151c91254e834a23c83f2da769412cd855b0a1b..50ea0ac8c9bf2c27a53323b93b5d473bd7e1d028 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -11,6 +11,7 @@
 
 #include <linux/spinlock.h>
 #include <linux/hardirq.h>
+#include <linux/uaccess.h>
 #include <linux/ftrace.h>
 #include <linux/percpu.h>
 #include <linux/init.h>
@@ -20,8 +21,7 @@
 #include <asm/nops.h>
 
 
-/* Long is fine, even if it is only 4 bytes ;-) */
-static long *ftrace_nop;
+static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
 
 union ftrace_code_union {
        char code[MCOUNT_INSN_SIZE];
@@ -32,17 +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;
 
@@ -56,48 +56,40 @@ 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)
 {
-       unsigned replaced;
-       unsigned old = *(unsigned *)old_code; /* 4 bytes */
-       unsigned new = *(unsigned *)new_code; /* 4 bytes */
-       unsigned char newch = new_code[4];
-       int faulted = 0;
+       unsigned char replaced[MCOUNT_INSN_SIZE];
 
        /*
         * 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.
+        * kstop_machine, or before SMP starts.
         */
-       asm volatile (
-               "1: lock\n"
-               "   cmpxchg %3, (%2)\n"
-               "   jnz 2f\n"
-               "   movb %b4, 4(%2)\n"
-               "2:\n"
-               ".section .fixup, \"ax\"\n"
-               "3:     movl $1, %0\n"
-               "       jmp 2b\n"
-               ".previous\n"
-               _ASM_EXTABLE(1b, 3b)
-               : "=r"(faulted), "=a"(replaced)
-               : "r"(ip), "r"(new), "c"(newch),
-                 "0"(faulted), "a"(old)
-               : "memory");
-       sync_core();
 
-       if (replaced != old && replaced != new)
-               faulted = 2;
+       /* 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 -EINVAL;
+
+       /* replace the text with the new text */
+       if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
+               return -EPERM;
+
+       sync_core();
 
-       return faulted;
+       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;
@@ -110,13 +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[];
@@ -139,19 +124,16 @@ 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"
-               ".byte 0x00,0x00,0x00\n"  /* 2 byte jmp + 3 bytes */
+               "nop\n"
+               "nop\n"
+               "nop\n"  /* 2 byte jmp + 3 bytes */
                "ftrace_test_p6nop:"
                P6_NOP5
                "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"
@@ -166,15 +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 1f\n");
-               ftrace_nop = (unsigned long *)ftrace_test_jmp;
+               pr_info("ftrace: converting mcount calls to jmp . + 5\n");
+               memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
                break;
        }