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/*
* 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 <linux/module.h>
#include <linux/stop_machine.h>
#include <asm/cacheflush.h>
#include <asm/opcodes.h>
#include <asm/ftrace.h>
#include <asm/insn.h>
#include <asm/set_memory.h>
#include <asm/patch.h>
#ifdef CONFIG_THUMB2_KERNEL
#define NOP 0xf85deb04 /* pop.w {lr} */
#else
#define NOP 0xe8bd4000 /* pop {lr} */
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
static int __ftrace_modify_code(void *data)
{
int *command = data;
ftrace_modify_all_code(*command);
return 0;
}
void arch_ftrace_update_code(int command)
{
stop_machine(__ftrace_modify_code, &command, NULL);
}
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;
}
int ftrace_arch_code_modify_prepare(void)
{
return 0;
}
int ftrace_arch_code_modify_post_process(void)
{
/* Make sure any TLB misses during machine stop are cleared. */
flush_tlb_all();
return 0;
}
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
return arm_gen_branch_link(pc, addr);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new, bool validate)
{
unsigned long replaced;
if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
old = __opcode_to_mem_thumb32(old);
new = __opcode_to_mem_thumb32(new);
} else {
old = __opcode_to_mem_arm(old);
new = __opcode_to_mem_arm(new);
}
if (validate) {
if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
return -EFAULT;
if (replaced != old)
return -EINVAL;
}
__patch_text((void *)pc, new);
return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long pc;
unsigned long new;
int ret;
pc = (unsigned long)&ftrace_call;
new = ftrace_call_replace(pc, (unsigned long)func);
ret = ftrace_modify_code(pc, 0, new, false);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!ret) {
pc = (unsigned long)&ftrace_regs_call;
new = ftrace_call_replace(pc, (unsigned long)func);
ret = ftrace_modify_code(pc, 0, new, false);
}
#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, true);
}
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long addr)
{
unsigned long new, old;
unsigned long ip = rec->ip;
old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
new = ftrace_call_replace(ip, adjust_address(rec, addr));
return ftrace_modify_code(rec->ip, old, new, true);
}
#endif
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, true);
return ret;
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long) &return_to_handler;
unsigned long old;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
old = *parent;
*parent = return_hooker;
if (function_graph_enter(old, self_addr, frame_pointer, NULL))
*parent = old;
}
#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_graph_call;
extern unsigned long ftrace_graph_call_old;
extern void ftrace_graph_caller_old(void);
extern unsigned long ftrace_graph_regs_call;
extern void ftrace_graph_regs_caller(void);
static int __ftrace_modify_caller(unsigned long *callsite,
void (*func) (void), bool enable)
{
unsigned long caller_fn = (unsigned long) func;
unsigned long pc = (unsigned long) callsite;
unsigned long branch = arm_gen_branch(pc, caller_fn);
unsigned long nop = 0xe1a00000; /* mov r0, r0 */
unsigned long old = enable ? nop : branch;
unsigned long new = enable ? branch : nop;
return ftrace_modify_code(pc, old, new, true);
}
static int ftrace_modify_graph_caller(bool enable)
{
int ret;
ret = __ftrace_modify_caller(&ftrace_graph_call,
ftrace_graph_caller,
enable);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!ret)
ret = __ftrace_modify_caller(&ftrace_graph_regs_call,
ftrace_graph_regs_caller,
enable);
#endif
return ret;
}
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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