Release 4.11 arch/arm64/kernel/ftrace.c

/*
 * arch/arm64/kernel/ftrace.c
 *
 * Copyright (C) 2013 Linaro Limited
 * Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/ftrace.h>
#include <linux/swab.h>
#include <linux/uaccess.h>

#include <asm/cacheflush.h>
#include <asm/ftrace.h>
#include <asm/insn.h>

#ifdef CONFIG_DYNAMIC_FTRACE
/*
 * Replace a single instruction, which may be a branch or NOP.
 * If @validate == true, a replaced instruction is checked against 'old'.
 */


static int ftrace_modify_code(unsigned long pc, u32 old, u32 new,
			      bool validate)
{
	u32 replaced;

	/*
         * Note:
         * We are paranoid about modifying text, as if a bug were to happen, it
         * could cause us to read or write to someplace that could cause harm.
         * Carefully read and modify the code with aarch64_insn_*() which uses
         * probe_kernel_*(), and make sure what we read is what we expected it
         * to be before modifying it.
         */
	if (validate) {
		if (aarch64_insn_read((void *)pc, &replaced))
			return -EFAULT;

		if (replaced != old)
			return -EINVAL;
	}
	if (aarch64_insn_patch_text_nosync((void *)pc, new))
		return -EPERM;

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
76
98.70%
1
50.00%
Li Bin
1
1.30%
1
50.00%
Total
77
100.00%
2
100.00%

/*
 * Replace tracer function in ftrace_caller()
 */


int ftrace_update_ftrace_func(ftrace_func_t func)
{
	unsigned long pc;
	u32 new;

	pc = (unsigned long)&ftrace_call;
	new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func,
					  AARCH64_INSN_BRANCH_LINK);

	return ftrace_modify_code(pc, 0, new, false);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
50
98.04%
1
50.00%
Catalin Marinas
1
1.96%
1
50.00%
Total
51
100.00%
2
100.00%

/*
 * Turn on the call to ftrace_caller() in instrumented function
 */


int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
	unsigned long pc = rec->ip;
	u32 old, new;

	old = aarch64_insn_gen_nop();
	new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);

	return ftrace_modify_code(pc, old, new, true);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
54
98.18%
1
50.00%
Catalin Marinas
1
1.82%
1
50.00%
Total
55
100.00%
2
100.00%

/*
 * Turn off the call to ftrace_caller() in instrumented function
 */


int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
		    unsigned long addr)
{
	unsigned long pc = rec->ip;
	u32 old, new;

	old = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
	new = aarch64_insn_gen_nop();

	return ftrace_modify_code(pc, old, new, true);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
59
98.33%
1
50.00%
Catalin Marinas
1
1.67%
1
50.00%
Total
60
100.00%
2
100.00%



void arch_ftrace_update_code(int command)
{
	ftrace_modify_all_code(command);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Li Bin
13
100.00%
1
100.00%
Total
13
100.00%
1
100.00%



int __init ftrace_dyn_arch_init(void)
{
	return 0;
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
11
100.00%
1
100.00%
Total
11
100.00%
1
100.00%

#endif /* CONFIG_DYNAMIC_FTRACE */

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/*
 * function_graph tracer expects ftrace_return_to_handler() to be called
 * on the way back to parent. For this purpose, this function is called
 * in _mcount() or ftrace_caller() to replace return address (*parent) on
 * the call stack to return_to_handler.
 *
 * Note that @frame_pointer is used only for sanity check later.
 */


void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
			   unsigned long frame_pointer)
{
	unsigned long return_hooker = (unsigned long)&return_to_handler;
	unsigned long old;
	struct ftrace_graph_ent trace;
	int err;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))
		return;

	/*
         * Note:
         * No protection against faulting at *parent, which may be seen
         * on other archs. It's unlikely on AArch64.
         */
	old = *parent;

	trace.func = self_addr;
	trace.depth = current->curr_ret_stack + 1;

	/* Only trace if the calling function expects to */
	if (!ftrace_graph_entry(&trace))
		return;

	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
				       frame_pointer, NULL);
	if (err == -EBUSY)
		return;
	else
		*parent = return_hooker;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
117
98.32%
2
66.67%
Josh Poimboeuf
2
1.68%
1
33.33%
Total
119
100.00%
3
100.00%

#ifdef CONFIG_DYNAMIC_FTRACE
/*
 * Turn on/off the call to ftrace_graph_caller() in ftrace_caller()
 * depending on @enable.
 */


static int ftrace_modify_graph_caller(bool enable)
{
	unsigned long pc = (unsigned long)&ftrace_graph_call;
	u32 branch, nop;

	branch = aarch64_insn_gen_branch_imm(pc,
					     (unsigned long)ftrace_graph_caller,
					     AARCH64_INSN_BRANCH_NOLINK);
	nop = aarch64_insn_gen_nop();

	if (enable)
		return ftrace_modify_code(pc, nop, branch, true);
	else
		return ftrace_modify_code(pc, branch, nop, true);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
73
98.65%
1
50.00%
Pratyush Anand
1
1.35%
1
50.00%
Total
74
100.00%
2
100.00%



int ftrace_enable_ftrace_graph_caller(void)
{
	return ftrace_modify_graph_caller(true);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
13
100.00%
1
100.00%
Total
13
100.00%
1
100.00%



int ftrace_disable_ftrace_graph_caller(void)
{
	return ftrace_modify_graph_caller(false);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
13
100.00%
1
100.00%
Total
13
100.00%
1
100.00%

#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
AKASHI Takahiro
509
96.22%
3
37.50%
Li Bin
14
2.65%
2
25.00%
Catalin Marinas
3
0.57%
1
12.50%
Josh Poimboeuf
2
0.38%
1
12.50%
Pratyush Anand
1
0.19%
1
12.50%
Total
529
100.00%
8
100.00%
Directory: arch/arm64/kernel

Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.