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/*
* ftrace graph code
*
* Copyright (C) 2009-2010 Analog Devices Inc.
* Licensed under the GPL-2 or later.
*/
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <linux/atomic.h>
#include <asm/cacheflush.h>
#ifdef CONFIG_DYNAMIC_FTRACE
static const unsigned char mnop[] = {
0x03, 0xc0, 0x00, 0x18, /* MNOP; */
0x03, 0xc0, 0x00, 0x18, /* MNOP; */
};
static void bfin_make_pcrel24(unsigned char *insn, unsigned long src,
unsigned long dst)
{
uint32_t pcrel = (dst - src) >> 1;
insn[0] = pcrel >> 16;
insn[1] = 0xe3;
insn[2] = pcrel;
insn[3] = pcrel >> 8;
}
#define bfin_make_pcrel24(insn, src, dst) bfin_make_pcrel24(insn, src, (unsigned long)(dst))
static int ftrace_modify_code(unsigned long ip, const unsigned char *code,
unsigned long len)
{
int ret = probe_kernel_write((void *)ip, (void *)code, len);
flush_icache_range(ip, ip + len);
return ret;
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
/* Turn the mcount call site into two MNOPs as those are 32bit insns */
return ftrace_modify_code(rec->ip, mnop, sizeof(mnop));
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
/* Restore the mcount call site */
unsigned char call[8];
call[0] = 0x67; /* [--SP] = RETS; */
call[1] = 0x01;
bfin_make_pcrel24(&call[2], rec->ip + 2, addr);
call[6] = 0x27; /* RETS = [SP++]; */
call[7] = 0x01;
return ftrace_modify_code(rec->ip, call, sizeof(call));
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned char call[4];
unsigned long ip = (unsigned long)&ftrace_call;
bfin_make_pcrel24(call, ip, func);
return ftrace_modify_code(ip, call, sizeof(call));
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void);
int ftrace_enable_ftrace_graph_caller(void)
{
unsigned long ip = (unsigned long)&ftrace_graph_call;
uint16_t jump_pcrel12 = ((unsigned long)&ftrace_graph_caller - ip) >> 1;
jump_pcrel12 |= 0x2000;
return ftrace_modify_code(ip, (void *)&jump_pcrel12, sizeof(jump_pcrel12));
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_code((unsigned long)&ftrace_graph_call, empty_zero_page, 2);
}
# endif
/*
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
{
struct ftrace_graph_ent trace;
unsigned long return_hooker = (unsigned long)&return_to_handler;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
if (ftrace_push_return_trace(*parent, self_addr, &trace.depth,
frame_pointer, NULL) == -EBUSY)
return;
trace.func = self_addr;
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;
return;
}
/* all is well in the world ! hijack RETS ... */
*parent = return_hooker;
}
#endif
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