Release 4.14 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/module.h>
#include <linux/swab.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/debug-monitors.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;
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
#ifdef CONFIG_ARM64_MODULE_PLTS
unsigned long *trampoline;
struct module *mod;
/*
* On kernels that support module PLTs, the offset between the
* branch instruction and its target may legally exceed the
* range of an ordinary relative 'bl' opcode. In this case, we
* need to branch via a trampoline in the module.
*
* NOTE: __module_text_address() must be called with preemption
* disabled, but we can rely on ftrace_lock to ensure that 'mod'
* retains its validity throughout the remainder of this code.
*/
preempt_disable();
mod = __module_text_address(pc);
preempt_enable();
if (WARN_ON(!mod))
return -EINVAL;
/*
* There is only one ftrace trampoline per module. For now,
* this is not a problem since on arm64, all dynamic ftrace
* invocations are routed via ftrace_caller(). This will need
* to be revisited if support for multiple ftrace entry points
* is added in the future, but for now, the pr_err() below
* deals with a theoretical issue only.
*/
trampoline = (unsigned long *)mod->arch.ftrace_trampoline;
if (trampoline[0] != addr) {
if (trampoline[0] != 0) {
pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
return -EINVAL;
}
/* point the trampoline to our ftrace entry point */
module_disable_ro(mod);
trampoline[0] = addr;
module_enable_ro(mod, true);
/* update trampoline before patching in the branch */
smp_wmb();
}
addr = (unsigned long)&trampoline[1];
#else /* CONFIG_ARM64_MODULE_PLTS */
return -EINVAL;
#endif /* CONFIG_ARM64_MODULE_PLTS */
}
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 |
| Ard Biesheuvel | 142 | 67.30% | 1 | 20.00% |
| AKASHI Takahiro | 49 | 23.22% | 1 | 20.00% |
| Mark Rutland | 11 | 5.21% | 1 | 20.00% |
| Will Deacon | 8 | 3.79% | 1 | 20.00% |
| Catalin Marinas | 1 | 0.47% | 1 | 20.00% |
| Total | 211 | 100.00% | 5 | 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;
bool validate = true;
u32 old = 0, new;
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
#ifdef CONFIG_ARM64_MODULE_PLTS
u32 replaced;
/*
* 'mod' is only set at module load time, but if we end up
* dealing with an out-of-range condition, we can assume it
* is due to a module being loaded far away from the kernel.
*/
if (!mod) {
preempt_disable();
mod = __module_text_address(pc);
preempt_enable();
if (WARN_ON(!mod))
return -EINVAL;
}
/*
* The instruction we are about to patch may be a branch and
* link instruction that was redirected via a PLT entry. In
* this case, the normal validation will fail, but we can at
* least check that we are dealing with a branch and link
* instruction that points into the right module.
*/
if (aarch64_insn_read((void *)pc, &replaced))
return -EFAULT;
if (!aarch64_insn_is_bl(replaced) ||
!within_module(pc + aarch64_get_branch_offset(replaced),
mod))
return -EINVAL;
validate = false;
#else /* CONFIG_ARM64_MODULE_PLTS */
return -EINVAL;
#endif /* CONFIG_ARM64_MODULE_PLTS */
} else {
old = aarch64_insn_gen_branch_imm(pc, addr,
AARCH64_INSN_BRANCH_LINK);
}
new = aarch64_insn_gen_nop();
return ftrace_modify_code(pc, old, new, validate);
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ard Biesheuvel | 114 | 59.07% | 1 | 20.00% |
| AKASHI Takahiro | 53 | 27.46% | 1 | 20.00% |
| Mark Rutland | 13 | 6.74% | 1 | 20.00% |
| Will Deacon | 12 | 6.22% | 1 | 20.00% |
| Catalin Marinas | 1 | 0.52% | 1 | 20.00% |
| Total | 193 | 100.00% | 5 | 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(¤t->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 | 498 | 60.44% | 3 | 25.00% |
| Ard Biesheuvel | 262 | 31.80% | 2 | 16.67% |
| Mark Rutland | 24 | 2.91% | 1 | 8.33% |
| Will Deacon | 20 | 2.43% | 1 | 8.33% |
| Li Bin | 14 | 1.70% | 2 | 16.67% |
| Catalin Marinas | 3 | 0.36% | 1 | 8.33% |
| Josh Poimboeuf | 2 | 0.24% | 1 | 8.33% |
| Pratyush Anand | 1 | 0.12% | 1 | 8.33% |
| Total | 824 | 100.00% | 12 | 100.00% |
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.