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/*
* Copyright 2012 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*
* TILE-Gx specific ftrace support
*/
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/ftrace.h>
#include <asm/sections.h>
#include <asm/insn.h>
#include <arch/opcode.h>
#ifdef CONFIG_DYNAMIC_FTRACE
static int machine_stopped __read_mostly;
int ftrace_arch_code_modify_prepare(void)
{
machine_stopped = 1;
return 0;
}
int ftrace_arch_code_modify_post_process(void)
{
flush_icache_range(0, CHIP_L1I_CACHE_SIZE());
machine_stopped = 0;
return 0;
}
/*
* Put { move r10, lr; jal ftrace_caller } in a bundle, this lets dynamic
* tracer just add one cycle overhead to every kernel function when disabled.
*/
static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
bool link)
{
tilegx_bundle_bits opcode_x0, opcode_x1;
long pcrel_by_instr = (addr - pc) >> TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES;
if (link) {
/* opcode: jal addr */
opcode_x1 =
create_Opcode_X1(JUMP_OPCODE_X1) |
create_JumpOpcodeExtension_X1(JAL_JUMP_OPCODE_X1) |
create_JumpOff_X1(pcrel_by_instr);
} else {
/* opcode: j addr */
opcode_x1 =
create_Opcode_X1(JUMP_OPCODE_X1) |
create_JumpOpcodeExtension_X1(J_JUMP_OPCODE_X1) |
create_JumpOff_X1(pcrel_by_instr);
}
/*
* Also put { move r10, lr; jal ftrace_stub } in a bundle, which
* is used to replace the instruction in address ftrace_call.
*/
if (addr == FTRACE_ADDR || addr == (unsigned long)ftrace_stub) {
/* opcode: or r10, lr, zero */
opcode_x0 =
create_Dest_X0(10) |
create_SrcA_X0(TREG_LR) |
create_SrcB_X0(TREG_ZERO) |
create_RRROpcodeExtension_X0(OR_RRR_0_OPCODE_X0) |
create_Opcode_X0(RRR_0_OPCODE_X0);
} else {
/* opcode: fnop */
opcode_x0 =
create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) |
create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) |
create_Opcode_X0(RRR_0_OPCODE_X0);
}
return opcode_x1 | opcode_x0;
}
static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
{
return NOP();
}
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
return ftrace_gen_branch(pc, addr, true);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new)
{
unsigned long pc_wr;
/* Check if the address is in kernel text space and module space. */
if (!kernel_text_address(pc))
return -EINVAL;
/* Operate on writable kernel text mapping. */
pc_wr = ktext_writable_addr(pc);
if (probe_kernel_write((void *)pc_wr, &new, MCOUNT_INSN_SIZE))
return -EPERM;
smp_wmb();
if (!machine_stopped && num_online_cpus() > 1)
flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long pc, old;
unsigned long new;
int ret;
pc = (unsigned long)&ftrace_call;
memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
new = ftrace_call_replace(pc, (unsigned long)func);
ret = ftrace_modify_code(pc, old, new);
return ret;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long new, old;
unsigned long ip = rec->ip;
old = ftrace_nop_replace(rec);
new = ftrace_call_replace(ip, addr);
return ftrace_modify_code(rec->ip, old, new);
}
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long ip = rec->ip;
unsigned long old;
unsigned long new;
int ret;
old = ftrace_call_replace(ip, addr);
new = ftrace_nop_replace(rec);
ret = ftrace_modify_code(ip, old, new);
return ret;
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long) &return_to_handler;
struct ftrace_graph_ent trace;
unsigned long old;
int err;
if (unlikely(atomic_read(¤t->tracing_graph_pause)))
return;
old = *parent;
*parent = return_hooker;
err = ftrace_push_return_trace(old, self_addr, &trace.depth,
frame_pointer, NULL);
if (err == -EBUSY) {
*parent = old;
return;
}
trace.func = self_addr;
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;
*parent = old;
}
}
#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_graph_call;
static int __ftrace_modify_caller(unsigned long *callsite,
void (*func) (void), bool enable)
{
unsigned long caller_fn = (unsigned long) func;
unsigned long pc = (unsigned long) callsite;
unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
unsigned long nop = NOP();
unsigned long old = enable ? nop : branch;
unsigned long new = enable ? branch : nop;
return ftrace_modify_code(pc, old, new);
}
static int ftrace_modify_graph_caller(bool enable)
{
int ret;
ret = __ftrace_modify_caller(&ftrace_graph_call,
ftrace_graph_caller,
enable);
return ret;
}
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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