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parisc/ftrace: use static key to enable/disable function graph tracer

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This avoids using dereference_function_descriptor in the ftrace code
path, and it's also faster.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Sven Schnelle 2021-10-23 20:21:01 +02:00 committed by Helge Deller
parent 44382af893
commit 98f2926171
1 changed files with 6 additions and 3 deletions
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9
arch/parisc/kernel/ftrace.c
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@ -15,6 +15,7 @@
#include <linux/uaccess.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/jump_label.h>
#include <asm/assembly.h>
#include <asm/sections.h>
@ -24,6 +25,8 @@
#define __hot __section(".text.hot")
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static DEFINE_STATIC_KEY_FALSE(ftrace_graph_enable);
/*
* Hook the return address and push it in the stack of return addrs
* in current thread info.
@ -60,9 +63,7 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
ftrace_func(self_addr, parent, function_trace_op, fregs);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (dereference_function_descriptor(ftrace_graph_return) !=
dereference_function_descriptor(ftrace_stub) ||
ftrace_graph_entry != ftrace_graph_entry_stub) {
if (static_branch_unlikely(&ftrace_graph_enable)) {
unsigned long *parent_rp;
/* calculate pointer to %rp in stack */
@ -80,11 +81,13 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
int ftrace_enable_ftrace_graph_caller(void)
{
static_key_enable(&ftrace_graph_enable.key);
return 0;
}
int ftrace_disable_ftrace_graph_caller(void)
{
static_key_enable(&ftrace_graph_enable.key);
return 0;
}
#endif