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