3b6c223b1b
This adds mcount recording and updates dynamic ftrace for ARM to work with the new ftrace dyamic tracing implementation. It also adds support for the mcount format used by newer ARM compilers. With dynamic tracing, mcount() is implemented as a nop. Callsites are patched on startup with nops, and dynamically patched to call to the ftrace_caller() routine as needed. Acked-by: Steven Rostedt <rostedt@goodmis.org> [recordmcount.pl change] Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
163 lines
3.6 KiB
C
163 lines
3.6 KiB
C
/*
|
|
* Dynamic function tracing support.
|
|
*
|
|
* Copyright (C) 2008 Abhishek Sagar <sagar.abhishek@gmail.com>
|
|
* Copyright (C) 2010 Rabin Vincent <rabin@rab.in>
|
|
*
|
|
* For licencing details, see COPYING.
|
|
*
|
|
* Defines low-level handling of mcount calls when the kernel
|
|
* is compiled with the -pg flag. When using dynamic ftrace, the
|
|
* mcount call-sites get patched with NOP till they are enabled.
|
|
* All code mutation routines here are called under stop_machine().
|
|
*/
|
|
|
|
#include <linux/ftrace.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/ftrace.h>
|
|
|
|
#define NOP 0xe8bd4000 /* pop {lr} */
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
#define OLD_MCOUNT_ADDR ((unsigned long) mcount)
|
|
#define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
|
|
|
|
#define OLD_NOP 0xe1a00000 /* mov r0, r0 */
|
|
|
|
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
|
|
{
|
|
return rec->arch.old_mcount ? OLD_NOP : NOP;
|
|
}
|
|
|
|
static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
if (!rec->arch.old_mcount)
|
|
return addr;
|
|
|
|
if (addr == MCOUNT_ADDR)
|
|
addr = OLD_MCOUNT_ADDR;
|
|
else if (addr == FTRACE_ADDR)
|
|
addr = OLD_FTRACE_ADDR;
|
|
|
|
return addr;
|
|
}
|
|
#else
|
|
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
|
|
{
|
|
return NOP;
|
|
}
|
|
|
|
static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
return addr;
|
|
}
|
|
#endif
|
|
|
|
/* construct a branch (BL) instruction to addr */
|
|
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
|
|
{
|
|
long offset;
|
|
|
|
offset = (long)addr - (long)(pc + 8);
|
|
if (unlikely(offset < -33554432 || offset > 33554428)) {
|
|
/* Can't generate branches that far (from ARM ARM). Ftrace
|
|
* doesn't generate branches outside of kernel text.
|
|
*/
|
|
WARN_ON_ONCE(1);
|
|
return 0;
|
|
}
|
|
|
|
offset = (offset >> 2) & 0x00ffffff;
|
|
|
|
return 0xeb000000 | offset;
|
|
}
|
|
|
|
static int ftrace_modify_code(unsigned long pc, unsigned long old,
|
|
unsigned long new)
|
|
{
|
|
unsigned long replaced;
|
|
|
|
if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
|
|
return -EFAULT;
|
|
|
|
if (replaced != old)
|
|
return -EINVAL;
|
|
|
|
if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE))
|
|
return -EPERM;
|
|
|
|
flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int ftrace_update_ftrace_func(ftrace_func_t func)
|
|
{
|
|
unsigned long pc, old;
|
|
unsigned long new;
|
|
int ret;
|
|
|
|
pc = (unsigned long)&ftrace_call;
|
|
memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
|
|
new = ftrace_call_replace(pc, (unsigned long)func);
|
|
|
|
ret = ftrace_modify_code(pc, old, new);
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
if (!ret) {
|
|
pc = (unsigned long)&ftrace_call_old;
|
|
memcpy(&old, &ftrace_call_old, MCOUNT_INSN_SIZE);
|
|
new = ftrace_call_replace(pc, (unsigned long)func);
|
|
|
|
ret = ftrace_modify_code(pc, old, new);
|
|
}
|
|
#endif
|
|
|
|
return ret;
|
|
}
|
|
|
|
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long new, old;
|
|
unsigned long ip = rec->ip;
|
|
|
|
old = ftrace_nop_replace(rec);
|
|
new = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
|
|
return ftrace_modify_code(rec->ip, old, new);
|
|
}
|
|
|
|
int ftrace_make_nop(struct module *mod,
|
|
struct dyn_ftrace *rec, unsigned long addr)
|
|
{
|
|
unsigned long ip = rec->ip;
|
|
unsigned long old;
|
|
unsigned long new;
|
|
int ret;
|
|
|
|
old = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
new = ftrace_nop_replace(rec);
|
|
ret = ftrace_modify_code(ip, old, new);
|
|
|
|
#ifdef CONFIG_OLD_MCOUNT
|
|
if (ret == -EINVAL && addr == MCOUNT_ADDR) {
|
|
rec->arch.old_mcount = true;
|
|
|
|
old = ftrace_call_replace(ip, adjust_address(rec, addr));
|
|
new = ftrace_nop_replace(rec);
|
|
ret = ftrace_modify_code(ip, old, new);
|
|
}
|
|
#endif
|
|
|
|
return ret;
|
|
}
|
|
|
|
int __init ftrace_dyn_arch_init(void *data)
|
|
{
|
|
*(unsigned long *)data = 0;
|
|
|
|
return 0;
|
|
}
|