tile: support ftrace on tilegx
This commit adds support for static ftrace, graph function support, and dynamic tracer support. Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
This commit is contained in:
Tony Lu
246
arch/tile/kernel/ftrace.c
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246
arch/tile/kernel/ftrace.c
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/*
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* Copyright 2012 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*
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* TILE-Gx specific ftrace support
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*/
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#include <linux/ftrace.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <asm/ftrace.h>
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#include <asm/sections.h>
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#include <arch/opcode.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static inline tilegx_bundle_bits NOP(void)
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{
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return create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) |
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create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) |
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create_Opcode_X0(RRR_0_OPCODE_X0) |
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create_UnaryOpcodeExtension_X1(NOP_UNARY_OPCODE_X1) |
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create_RRROpcodeExtension_X1(UNARY_RRR_0_OPCODE_X1) |
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create_Opcode_X1(RRR_0_OPCODE_X1);
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}
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static int machine_stopped __read_mostly;
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int ftrace_arch_code_modify_prepare(void)
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{
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machine_stopped = 1;
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return 0;
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}
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int ftrace_arch_code_modify_post_process(void)
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{
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flush_icache_range(0, CHIP_L1I_CACHE_SIZE());
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machine_stopped = 0;
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return 0;
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}
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/*
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* Put { move r10, lr; jal ftrace_caller } in a bundle, this lets dynamic
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* tracer just add one cycle overhead to every kernel function when disabled.
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*/
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static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
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bool link)
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{
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tilegx_bundle_bits opcode_x0, opcode_x1;
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long pcrel_by_instr = (addr - pc) >> TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES;
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if (link) {
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/* opcode: jal addr */
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opcode_x1 =
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create_Opcode_X1(JUMP_OPCODE_X1) |
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create_JumpOpcodeExtension_X1(JAL_JUMP_OPCODE_X1) |
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create_JumpOff_X1(pcrel_by_instr);
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} else {
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/* opcode: j addr */
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opcode_x1 =
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create_Opcode_X1(JUMP_OPCODE_X1) |
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create_JumpOpcodeExtension_X1(J_JUMP_OPCODE_X1) |
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create_JumpOff_X1(pcrel_by_instr);
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}
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if (addr == FTRACE_ADDR) {
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/* opcode: or r10, lr, zero */
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opcode_x0 =
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create_Dest_X0(10) |
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create_SrcA_X0(TREG_LR) |
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create_SrcB_X0(TREG_ZERO) |
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create_RRROpcodeExtension_X0(OR_RRR_0_OPCODE_X0) |
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create_Opcode_X0(RRR_0_OPCODE_X0);
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} else {
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/* opcode: fnop */
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opcode_x0 =
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create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) |
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create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) |
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create_Opcode_X0(RRR_0_OPCODE_X0);
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}
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return opcode_x1 | opcode_x0;
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}
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static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec)
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{
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return NOP();
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}
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static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
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{
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return ftrace_gen_branch(pc, addr, true);
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}
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static int ftrace_modify_code(unsigned long pc, unsigned long old,
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unsigned long new)
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{
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unsigned long pc_wr;
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/* Check if the address is in kernel text space and module space. */
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if (!kernel_text_address(pc))
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return -EINVAL;
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/* Operate on writable kernel text mapping. */
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pc_wr = pc - MEM_SV_START + PAGE_OFFSET;
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if (probe_kernel_write((void *)pc_wr, &new, MCOUNT_INSN_SIZE))
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return -EPERM;
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smp_wmb();
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if (!machine_stopped && num_online_cpus() > 1)
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flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
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return 0;
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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, old;
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unsigned long new;
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int ret;
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pc = (unsigned long)&ftrace_call;
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memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE);
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new = ftrace_call_replace(pc, (unsigned long)func);
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ret = ftrace_modify_code(pc, old, new);
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return ret;
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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 long new, old;
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unsigned long ip = rec->ip;
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old = ftrace_nop_replace(rec);
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new = ftrace_call_replace(ip, addr);
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return ftrace_modify_code(rec->ip, old, new);
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}
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned long old;
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unsigned long new;
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int ret;
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old = ftrace_call_replace(ip, addr);
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new = ftrace_nop_replace(rec);
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ret = ftrace_modify_code(ip, old, new);
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return ret;
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}
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int __init ftrace_dyn_arch_init(void *data)
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{
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*(unsigned long *)data = 0;
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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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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struct ftrace_graph_ent trace;
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unsigned long old;
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int err;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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*parent = return_hooker;
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err = ftrace_push_return_trace(old, self_addr, &trace.depth,
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frame_pointer);
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if (err == -EBUSY) {
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*parent = old;
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return;
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}
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trace.func = self_addr;
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/* Only trace if the calling function expects to */
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if (!ftrace_graph_entry(&trace)) {
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current->curr_ret_stack--;
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*parent = old;
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}
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}
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern unsigned long ftrace_graph_call;
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static int __ftrace_modify_caller(unsigned long *callsite,
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void (*func) (void), bool enable)
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{
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unsigned long caller_fn = (unsigned long) func;
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unsigned long pc = (unsigned long) callsite;
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unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
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unsigned long nop = NOP();
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unsigned long old = enable ? nop : branch;
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unsigned long new = enable ? branch : nop;
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return ftrace_modify_code(pc, old, new);
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}
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static int ftrace_modify_graph_caller(bool enable)
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{
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int ret;
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ret = __ftrace_modify_caller(&ftrace_graph_call,
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ftrace_graph_caller,
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enable);
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return ret;
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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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