177 lines
4.2 KiB
C
177 lines
4.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Based on arch/arm64/kernel/ftrace.c
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*
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* Copyright (C) 2019 os kernel team
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/ftrace.h>
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#include <asm/ftrace.h>
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#ifdef CONFIG_FUNCTION_TRACER
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EXPORT_SYMBOL(_mcount);
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define TI_FTRACE_ADDR (offsetof(struct thread_info, dyn_ftrace_addr))
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#define TI_FTRACE_REGS_ADDR \
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(offsetof(struct thread_info, dyn_ftrace_regs_addr))
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unsigned long current_tracer = (unsigned long)ftrace_stub;
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/*
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* Replace a single instruction, which may be a branch or NOP.
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*/
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static int ftrace_modify_code(unsigned long pc, u32 new)
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{
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if (sw64_insn_write((void *)pc, new))
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return -EPERM;
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return 0;
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}
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/*
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* Replace tracer function in ftrace_caller()
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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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u32 new;
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int ret;
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current_tracer = (unsigned long)func;
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pc = (unsigned long)&ftrace_call;
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new = SW64_CALL(R26, R27, 0);
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ret = ftrace_modify_code(pc, new);
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if (!ret) {
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pc = (unsigned long)&ftrace_regs_call;
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new = SW64_CALL(R26, R27, 0);
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ret = ftrace_modify_code(pc, new);
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}
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return ret;
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}
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/*
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* Turn on the call to ftrace_caller() in instrumented function
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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 int insn[3];
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unsigned long pc = rec->ip + MCOUNT_LDGP_SIZE;
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unsigned long offset;
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if (addr == FTRACE_ADDR)
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offset = TI_FTRACE_ADDR;
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else
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offset = TI_FTRACE_REGS_ADDR;
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insn[0] = SW64_NOP;
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/* ldl r28,(ftrace_addr_offset)(r8) */
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insn[1] = (0x23U << 26) | (28U << 21) | (8U << 16) | offset;
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insn[2] = SW64_CALL(R28, R28, 0);
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/* replace the 3 mcount instructions at once */
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return copy_to_kernel_nofault((void *)pc, insn, 3 * SW64_INSN_SIZE);
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}
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/*
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* Turn off the call to ftrace_caller() in instrumented function
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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 long pc = rec->ip + MCOUNT_LDGP_SIZE;
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unsigned int insn[3] = {SW64_NOP, SW64_NOP, SW64_NOP};
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return copy_to_kernel_nofault((void *)pc, insn, 3 * SW64_INSN_SIZE);
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}
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void arch_ftrace_update_code(int command)
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{
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ftrace_modify_all_code(command);
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}
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int __init ftrace_dyn_arch_init(void)
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{
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struct thread_info *ti = task_thread_info(&init_task);
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ti->dyn_ftrace_addr = FTRACE_ADDR;
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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ti->dyn_ftrace_regs_addr = FTRACE_REGS_ADDR;
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#endif
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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 0;
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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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* function_graph tracer expects ftrace_return_to_handler() to be called
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* on the way back to parent. For this purpose, this function is called
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* in _mcount() or ftrace_caller() to replace return address (*parent) on
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* the call stack to return_to_handler.
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*
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* Note that @frame_pointer is used only for sanity check later.
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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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* Note:
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* No protection against faulting at *parent, which may be seen
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* on other archs. It's unlikely on AArch64.
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*/
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old = *parent;
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if (!function_graph_enter(old, self_addr, frame_pointer, NULL))
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*parent = return_hooker;
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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/*
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* Turn on/off the call to ftrace_graph_caller() in ftrace_caller()
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* depending on @enable.
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*/
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static int ftrace_modify_graph_caller(bool enable)
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{
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unsigned long pc = (unsigned long)&ftrace_graph_call;
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u32 new = SW64_NOP;
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if (enable)
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new = SW64_CALL(R26, R27, 0);
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return ftrace_modify_code(pc, new);
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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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