Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 | /*
* Code for replacing ftrace calls with jumps.
*
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
*
* Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
*
*/
#include <linux/spinlock.h>
#include <linux/hardirq.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/list.h>
#include <asm/cacheflush.h>
#include <asm/ftrace.h>
static unsigned int ftrace_nop = 0x60000000;
#ifdef CONFIG_PPC32
# define GET_ADDR(addr) addr
#else
/* PowerPC64's functions are data that points to the functions */
# define GET_ADDR(addr) *(unsigned long *)addr
#endif
static unsigned int notrace ftrace_calc_offset(long ip, long addr)
{
return (int)(addr - ip);
}
notrace unsigned char *ftrace_nop_replace(void)
{
return (char *)&ftrace_nop;
}
notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
static unsigned int op;
/*
* It would be nice to just use create_function_call, but that will
* update the code itself. Here we need to just return the
* instruction that is going to be modified, without modifying the
* code.
*/
addr = GET_ADDR(addr);
/* Set to "bl addr" */
op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
/*
* No locking needed, this must be called via kstop_machine
* which in essence is like running on a uniprocessor machine.
*/
return (unsigned char *)&op;
}
#ifdef CONFIG_PPC64
# define _ASM_ALIGN " .align 3 "
# define _ASM_PTR " .llong "
#else
# define _ASM_ALIGN " .align 2 "
# define _ASM_PTR " .long "
#endif
notrace int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code)
{
unsigned replaced;
unsigned old = *(unsigned *)old_code;
unsigned new = *(unsigned *)new_code;
int faulted = 0;
/*
* Note: Due to modules and __init, code can
* disappear and change, we need to protect against faulting
* as well as code changing.
*
* No real locking needed, this code is run through
* kstop_machine.
*/
asm volatile (
"1: lwz %1, 0(%2)\n"
" cmpw %1, %5\n"
" bne 2f\n"
" stwu %3, 0(%2)\n"
"2:\n"
".section .fixup, \"ax\"\n"
"3: li %0, 1\n"
" b 2b\n"
".previous\n"
".section __ex_table,\"a\"\n"
_ASM_ALIGN "\n"
_ASM_PTR "1b, 3b\n"
".previous"
: "=r"(faulted), "=r"(replaced)
: "r"(ip), "r"(new),
"0"(faulted), "r"(old)
: "memory");
if (replaced != old && replaced != new)
faulted = 2;
if (!faulted)
flush_icache_range(ip, ip + 8);
return faulted;
}
notrace int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
unsigned char old[MCOUNT_INSN_SIZE], *new;
int ret;
memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(ip, (unsigned long)func);
ret = ftrace_modify_code(ip, old, new);
return ret;
}
notrace int ftrace_mcount_set(unsigned long *data)
{
unsigned long ip = (long)(&mcount_call);
unsigned long *addr = data;
unsigned char old[MCOUNT_INSN_SIZE], *new;
/*
* Replace the mcount stub with a pointer to the
* ip recorder function.
*/
memcpy(old, &mcount_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(ip, *addr);
*addr = ftrace_modify_code(ip, old, new);
return 0;
}
int __init ftrace_dyn_arch_init(void *data)
{
/* This is running in kstop_machine */
ftrace_mcount_set(data);
return 0;
}
|