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![Christoph Hellwig](/assets/img/avatar_default.png)
Better describe what these functions do. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
239 lines
5.4 KiB
C
239 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
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#include <linux/ftrace.h>
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#include <linux/uaccess.h>
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#include <linux/stop_machine.h>
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#include <asm/cacheflush.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define NOP 0x4000
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#define NOP32_HI 0xc400
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#define NOP32_LO 0x4820
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#define PUSH_LR 0x14d0
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#define MOVIH_LINK 0xea3a
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#define ORI_LINK 0xef5a
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#define JSR_LINK 0xe8fa
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#define BSR_LINK 0xe000
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/*
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* Gcc-csky with -pg will insert stub in function prologue:
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* push lr
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* jbsr _mcount
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* nop32
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* nop32
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*
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* If the (callee - current_pc) is less then 64MB, we'll use bsr:
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* push lr
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* bsr _mcount
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* nop32
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* nop32
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* else we'll use (movih + ori + jsr):
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* push lr
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* movih r26, ...
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* ori r26, ...
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* jsr r26
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*
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* (r26 is our reserved link-reg)
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*
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*/
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static inline void make_jbsr(unsigned long callee, unsigned long pc,
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uint16_t *call, bool nolr)
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{
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long offset;
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call[0] = nolr ? NOP : PUSH_LR;
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offset = (long) callee - (long) pc;
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if (unlikely(offset < -67108864 || offset > 67108864)) {
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call[1] = MOVIH_LINK;
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call[2] = callee >> 16;
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call[3] = ORI_LINK;
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call[4] = callee & 0xffff;
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call[5] = JSR_LINK;
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call[6] = 0;
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} else {
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offset = offset >> 1;
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call[1] = BSR_LINK |
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((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
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call[2] = (uint16_t)((unsigned long) offset & 0xffff);
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call[3] = call[5] = NOP32_HI;
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call[4] = call[6] = NOP32_LO;
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}
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}
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static uint16_t nops[7] = {NOP, NOP32_HI, NOP32_LO, NOP32_HI, NOP32_LO,
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NOP32_HI, NOP32_LO};
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static int ftrace_check_current_nop(unsigned long hook)
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{
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uint16_t olds[7];
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unsigned long hook_pos = hook - 2;
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if (copy_from_kernel_nofault((void *)olds, (void *)hook_pos,
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sizeof(nops)))
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return -EFAULT;
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if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {
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pr_err("%p: nop but get (%04x %04x %04x %04x %04x %04x %04x)\n",
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(void *)hook_pos,
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olds[0], olds[1], olds[2], olds[3], olds[4], olds[5],
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olds[6]);
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return -EINVAL;
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}
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return 0;
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}
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static int ftrace_modify_code(unsigned long hook, unsigned long target,
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bool enable, bool nolr)
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{
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uint16_t call[7];
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unsigned long hook_pos = hook - 2;
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int ret = 0;
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make_jbsr(target, hook, call, nolr);
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ret = copy_to_kernel_nofault((void *)hook_pos, enable ? call : nops,
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sizeof(nops));
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if (ret)
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return -EPERM;
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flush_icache_range(hook_pos, hook_pos + MCOUNT_INSN_SIZE);
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return 0;
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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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int ret = ftrace_check_current_nop(rec->ip);
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if (ret)
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return ret;
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return ftrace_modify_code(rec->ip, addr, true, false);
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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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return ftrace_modify_code(rec->ip, addr, false, false);
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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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int ret = ftrace_modify_code((unsigned long)&ftrace_call,
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(unsigned long)func, true, true);
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if (!ret)
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ret = ftrace_modify_code((unsigned long)&ftrace_regs_call,
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(unsigned long)func, true, true);
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return ret;
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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 /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
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unsigned long addr)
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{
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return ftrace_modify_code(rec->ip, addr, true, true);
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}
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#endif
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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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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unsigned long return_hooker = (unsigned long)&return_to_handler;
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unsigned long old;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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if (!function_graph_enter(old, self_addr,
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*(unsigned long *)frame_pointer, parent)) {
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/*
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* For csky-gcc function has sub-call:
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* subi sp, sp, 8
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* stw r8, (sp, 0)
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* mov r8, sp
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* st.w r15, (sp, 0x4)
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* push r15
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* jl _mcount
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* We only need set *parent for resume
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*
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* For csky-gcc function has no sub-call:
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* subi sp, sp, 4
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* stw r8, (sp, 0)
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* mov r8, sp
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* push r15
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* jl _mcount
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* We need set *parent and *(frame_pointer + 4) for resume,
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* because lr is resumed twice.
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*/
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*parent = return_hooker;
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frame_pointer += 4;
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if (*(unsigned long *)frame_pointer == old)
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*(unsigned long *)frame_pointer = return_hooker;
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}
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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int ftrace_enable_ftrace_graph_caller(void)
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{
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return ftrace_modify_code((unsigned long)&ftrace_graph_call,
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(unsigned long)&ftrace_graph_caller, true, true);
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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,
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(unsigned long)&ftrace_graph_caller, false, true);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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#ifdef CONFIG_DYNAMIC_FTRACE
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#ifndef CONFIG_CPU_HAS_ICACHE_INS
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struct ftrace_modify_param {
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int command;
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atomic_t cpu_count;
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};
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static int __ftrace_modify_code(void *data)
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{
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struct ftrace_modify_param *param = data;
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if (atomic_inc_return(¶m->cpu_count) == 1) {
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ftrace_modify_all_code(param->command);
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atomic_inc(¶m->cpu_count);
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} else {
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while (atomic_read(¶m->cpu_count) <= num_online_cpus())
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cpu_relax();
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local_icache_inv_all(NULL);
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}
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return 0;
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}
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void arch_ftrace_update_code(int command)
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{
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struct ftrace_modify_param param = { command, ATOMIC_INIT(0) };
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stop_machine(__ftrace_modify_code, ¶m, cpu_online_mask);
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}
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#endif
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#endif /* CONFIG_DYNAMIC_FTRACE */
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/* _mcount is defined in abi's mcount.S */
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EXPORT_SYMBOL(_mcount);
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