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269 lines
5.9 KiB
269 lines
5.9 KiB
/* |
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* Dynamic function tracing support. |
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* |
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* Copyright (C) 2008 Abhishek Sagar <[email protected]> |
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* Copyright (C) 2010 Rabin Vincent <[email protected]> |
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* |
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* For licencing details, see COPYING. |
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* |
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* Defines low-level handling of mcount calls when the kernel |
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* is compiled with the -pg flag. When using dynamic ftrace, the |
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* mcount call-sites get patched with NOP till they are enabled. |
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* All code mutation routines here are called under stop_machine(). |
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*/ |
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#include <linux/ftrace.h> |
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#include <linux/uaccess.h> |
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#include <linux/module.h> |
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#include <linux/stop_machine.h> |
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#include <asm/cacheflush.h> |
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#include <asm/opcodes.h> |
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#include <asm/ftrace.h> |
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#include <asm/insn.h> |
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#include <asm/set_memory.h> |
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#include <asm/patch.h> |
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#ifdef CONFIG_THUMB2_KERNEL |
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#define NOP 0xf85deb04 /* pop.w {lr} */ |
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#else |
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#define NOP 0xe8bd4000 /* pop {lr} */ |
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#endif |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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static int __ftrace_modify_code(void *data) |
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{ |
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int *command = data; |
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ftrace_modify_all_code(*command); |
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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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stop_machine(__ftrace_modify_code, &command, NULL); |
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} |
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static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) |
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{ |
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return NOP; |
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} |
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static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr) |
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{ |
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return addr; |
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} |
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int ftrace_arch_code_modify_prepare(void) |
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{ |
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return 0; |
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} |
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int ftrace_arch_code_modify_post_process(void) |
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{ |
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/* Make sure any TLB misses during machine stop are cleared. */ |
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flush_tlb_all(); |
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return 0; |
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} |
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static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr, |
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bool warn) |
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{ |
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return arm_gen_branch_link(pc, addr, warn); |
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} |
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static int ftrace_modify_code(unsigned long pc, unsigned long old, |
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unsigned long new, bool validate) |
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{ |
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unsigned long replaced; |
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if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) |
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old = __opcode_to_mem_thumb32(old); |
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else |
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old = __opcode_to_mem_arm(old); |
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if (validate) { |
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if (copy_from_kernel_nofault(&replaced, (void *)pc, |
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MCOUNT_INSN_SIZE)) |
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return -EFAULT; |
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if (replaced != old) |
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return -EINVAL; |
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} |
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__patch_text((void *)pc, new); |
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return 0; |
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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 long pc; |
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unsigned long new; |
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int ret; |
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pc = (unsigned long)&ftrace_call; |
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new = ftrace_call_replace(pc, (unsigned long)func, true); |
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ret = ftrace_modify_code(pc, 0, new, false); |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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if (!ret) { |
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pc = (unsigned long)&ftrace_regs_call; |
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new = ftrace_call_replace(pc, (unsigned long)func, true); |
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ret = ftrace_modify_code(pc, 0, new, false); |
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} |
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#endif |
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return ret; |
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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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unsigned long new, old; |
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unsigned long ip = rec->ip; |
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unsigned long aaddr = adjust_address(rec, addr); |
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struct module *mod = NULL; |
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#ifdef CONFIG_ARM_MODULE_PLTS |
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mod = rec->arch.mod; |
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#endif |
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old = ftrace_nop_replace(rec); |
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new = ftrace_call_replace(ip, aaddr, !mod); |
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#ifdef CONFIG_ARM_MODULE_PLTS |
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if (!new && mod) { |
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aaddr = get_module_plt(mod, ip, aaddr); |
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new = ftrace_call_replace(ip, aaddr, true); |
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} |
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#endif |
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return ftrace_modify_code(rec->ip, old, new, true); |
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} |
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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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unsigned long new, old; |
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unsigned long ip = rec->ip; |
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old = ftrace_call_replace(ip, adjust_address(rec, old_addr), true); |
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new = ftrace_call_replace(ip, adjust_address(rec, addr), true); |
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return ftrace_modify_code(rec->ip, old, new, true); |
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} |
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#endif |
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int ftrace_make_nop(struct module *mod, |
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struct dyn_ftrace *rec, unsigned long addr) |
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{ |
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unsigned long aaddr = adjust_address(rec, addr); |
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unsigned long ip = rec->ip; |
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unsigned long old; |
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unsigned long new; |
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int ret; |
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#ifdef CONFIG_ARM_MODULE_PLTS |
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/* mod is only supplied during module loading */ |
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if (!mod) |
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mod = rec->arch.mod; |
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else |
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rec->arch.mod = mod; |
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#endif |
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old = ftrace_call_replace(ip, aaddr, |
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!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); |
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#ifdef CONFIG_ARM_MODULE_PLTS |
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if (!old && mod) { |
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aaddr = get_module_plt(mod, ip, aaddr); |
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old = ftrace_call_replace(ip, aaddr, true); |
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} |
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#endif |
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new = ftrace_nop_replace(rec); |
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ret = ftrace_modify_code(ip, old, new, 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_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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*parent = return_hooker; |
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if (function_graph_enter(old, self_addr, frame_pointer, NULL)) |
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*parent = old; |
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} |
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#ifdef CONFIG_DYNAMIC_FTRACE |
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extern unsigned long ftrace_graph_call; |
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extern unsigned long ftrace_graph_call_old; |
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extern void ftrace_graph_caller_old(void); |
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extern unsigned long ftrace_graph_regs_call; |
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extern void ftrace_graph_regs_caller(void); |
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static int __ftrace_modify_caller(unsigned long *callsite, |
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void (*func) (void), bool enable) |
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{ |
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unsigned long caller_fn = (unsigned long) func; |
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unsigned long pc = (unsigned long) callsite; |
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unsigned long branch = arm_gen_branch(pc, caller_fn); |
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unsigned long nop = 0xe1a00000; /* mov r0, r0 */ |
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unsigned long old = enable ? nop : branch; |
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unsigned long new = enable ? branch : nop; |
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return ftrace_modify_code(pc, old, new, true); |
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} |
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static int ftrace_modify_graph_caller(bool enable) |
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{ |
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int ret; |
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ret = __ftrace_modify_caller(&ftrace_graph_call, |
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ftrace_graph_caller, |
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enable); |
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS |
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if (!ret) |
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ret = __ftrace_modify_caller(&ftrace_graph_regs_call, |
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ftrace_graph_regs_caller, |
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enable); |
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#endif |
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return ret; |
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} |
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int ftrace_enable_ftrace_graph_caller(void) |
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{ |
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return ftrace_modify_graph_caller(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_graph_caller(false); |
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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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