230 lines
5.4 KiB
C
230 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2013 Linaro Limited
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* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
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* Copyright (C) 2017 Andes Technology Corporation
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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/memory.h>
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#include <asm/cacheflush.h>
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#include <asm/patch.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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int ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
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{
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mutex_lock(&text_mutex);
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return 0;
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}
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int ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
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{
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mutex_unlock(&text_mutex);
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return 0;
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}
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static int ftrace_check_current_call(unsigned long hook_pos,
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unsigned int *expected)
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{
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unsigned int replaced[2];
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unsigned int nops[2] = {NOP4, NOP4};
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/* we expect nops at the hook position */
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if (!expected)
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expected = nops;
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/*
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* Read the text we want to modify;
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* return must be -EFAULT on read error
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*/
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if (copy_from_kernel_nofault(replaced, (void *)hook_pos,
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MCOUNT_INSN_SIZE))
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return -EFAULT;
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/*
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* Make sure it is what we expect it to be;
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* return must be -EINVAL on failed comparison
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*/
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if (memcmp(expected, replaced, sizeof(replaced))) {
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pr_err("%p: expected (%08x %08x) but got (%08x %08x)\n",
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(void *)hook_pos, expected[0], expected[1], replaced[0],
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replaced[1]);
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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_call(unsigned long hook_pos, unsigned long target,
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bool enable)
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{
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unsigned int call[2];
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unsigned int nops[2] = {NOP4, NOP4};
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make_call(hook_pos, target, call);
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/* Replace the auipc-jalr pair at once. Return -EPERM on write error. */
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if (patch_text_nosync
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((void *)hook_pos, enable ? call : nops, MCOUNT_INSN_SIZE))
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return -EPERM;
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return 0;
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}
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/*
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* Put 5 instructions with 16 bytes at the front of function within
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* patchable function entry nops' area.
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*
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* 0: REG_S ra, -SZREG(sp)
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* 1: auipc ra, 0x?
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* 2: jalr -?(ra)
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* 3: REG_L ra, -SZREG(sp)
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*
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* So the opcodes is:
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* 0: 0xfe113c23 (sd)/0xfe112e23 (sw)
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* 1: 0x???????? -> auipc
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* 2: 0x???????? -> jalr
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* 3: 0xff813083 (ld)/0xffc12083 (lw)
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*/
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#if __riscv_xlen == 64
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#define INSN0 0xfe113c23
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#define INSN3 0xff813083
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#elif __riscv_xlen == 32
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#define INSN0 0xfe112e23
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#define INSN3 0xffc12083
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#endif
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#define FUNC_ENTRY_SIZE 16
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#define FUNC_ENTRY_JMP 4
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int call[4] = {INSN0, 0, 0, INSN3};
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unsigned long target = addr;
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unsigned long caller = rec->ip + FUNC_ENTRY_JMP;
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call[1] = to_auipc_insn((unsigned int)(target - caller));
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call[2] = to_jalr_insn((unsigned int)(target - caller));
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if (patch_text_nosync((void *)rec->ip, call, FUNC_ENTRY_SIZE))
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return -EPERM;
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return 0;
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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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unsigned int nops[4] = {NOP4, NOP4, NOP4, NOP4};
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if (patch_text_nosync((void *)rec->ip, nops, FUNC_ENTRY_SIZE))
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return -EPERM;
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return 0;
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}
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/*
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* This is called early on, and isn't wrapped by
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* ftrace_arch_code_modify_{prepare,post_process}() and therefor doesn't hold
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* text_mutex, which triggers a lockdep failure. SMP isn't running so we could
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* just directly poke the text, but it's simpler to just take the lock
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* ourselves.
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*/
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int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
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{
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int out;
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ftrace_arch_code_modify_prepare();
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out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
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ftrace_arch_code_modify_post_process();
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return out;
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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_call((unsigned long)&ftrace_call,
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(unsigned long)func, true);
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if (!ret) {
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ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call,
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(unsigned long)func, true);
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}
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return ret;
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}
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#endif
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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 int call[2];
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unsigned long caller = rec->ip + FUNC_ENTRY_JMP;
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int ret;
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make_call(caller, old_addr, call);
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ret = ftrace_check_current_call(caller, call);
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if (ret)
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return ret;
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return __ftrace_modify_call(caller, addr, true);
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}
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#endif
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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/*
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* Most of this function is copied from arm64.
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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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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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/*
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* We don't suffer access faults, so no extra fault-recovery assembly
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* is needed here.
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*/
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old = *parent;
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if (!function_graph_enter(old, self_addr, frame_pointer, parent))
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*parent = return_hooker;
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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extern void ftrace_graph_regs_call(void);
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int ftrace_enable_ftrace_graph_caller(void)
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{
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int ret;
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ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,
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(unsigned long)&prepare_ftrace_return, true);
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if (ret)
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return ret;
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return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,
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(unsigned long)&prepare_ftrace_return, true);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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int ret;
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ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call,
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(unsigned long)&prepare_ftrace_return, false);
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if (ret)
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return ret;
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return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,
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(unsigned long)&prepare_ftrace_return, 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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