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Diffstat (limited to 'arch/x86/kernel/ftrace.c')
-rw-r--r--arch/x86/kernel/ftrace.c50
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;
}