15adc04898
The entire file of ftrace.c in the arch code needs to be marked as notrace. It is much cleaner to do this from the Makefile with CFLAGS_REMOVE_ftrace.o. [ powerpc already had this in its Makefile. ] Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
137 lines
2.9 KiB
C
137 lines
2.9 KiB
C
/*
|
|
* 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 ftrace_calc_offset(long ip, long addr)
|
|
{
|
|
return (int)(addr - ip);
|
|
}
|
|
|
|
unsigned char *ftrace_nop_replace(void)
|
|
{
|
|
return (char *)&ftrace_nop;
|
|
}
|
|
|
|
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
|
|
|
|
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;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
int __init ftrace_dyn_arch_init(void *data)
|
|
{
|
|
/* This is running in kstop_machine */
|
|
|
|
ftrace_mcount_set(data);
|
|
|
|
return 0;
|
|
}
|
|
|