1/* 2 * Copyright 2012 Tilera Corporation. All Rights Reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation, version 2. 7 * 8 * This program is distributed in the hope that it will be useful, but 9 * WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or 11 * NON INFRINGEMENT. See the GNU General Public License for 12 * more details. 13 * 14 * TILE-Gx specific ftrace support 15 */ 16 17#include <linux/ftrace.h> 18#include <linux/uaccess.h> 19 20#include <asm/cacheflush.h> 21#include <asm/ftrace.h> 22#include <asm/sections.h> 23 24#include <arch/opcode.h> 25 26#ifdef CONFIG_DYNAMIC_FTRACE 27 28static inline tilegx_bundle_bits NOP(void) 29{ 30 return create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) | 31 create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) | 32 create_Opcode_X0(RRR_0_OPCODE_X0) | 33 create_UnaryOpcodeExtension_X1(NOP_UNARY_OPCODE_X1) | 34 create_RRROpcodeExtension_X1(UNARY_RRR_0_OPCODE_X1) | 35 create_Opcode_X1(RRR_0_OPCODE_X1); 36} 37 38static int machine_stopped __read_mostly; 39 40int ftrace_arch_code_modify_prepare(void) 41{ 42 machine_stopped = 1; 43 return 0; 44} 45 46int ftrace_arch_code_modify_post_process(void) 47{ 48 flush_icache_range(0, CHIP_L1I_CACHE_SIZE()); 49 machine_stopped = 0; 50 return 0; 51} 52 53/* 54 * Put { move r10, lr; jal ftrace_caller } in a bundle, this lets dynamic 55 * tracer just add one cycle overhead to every kernel function when disabled. 56 */ 57static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr, 58 bool link) 59{ 60 tilegx_bundle_bits opcode_x0, opcode_x1; 61 long pcrel_by_instr = (addr - pc) >> TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES; 62 63 if (link) { 64 /* opcode: jal addr */ 65 opcode_x1 = 66 create_Opcode_X1(JUMP_OPCODE_X1) | 67 create_JumpOpcodeExtension_X1(JAL_JUMP_OPCODE_X1) | 68 create_JumpOff_X1(pcrel_by_instr); 69 } else { 70 /* opcode: j addr */ 71 opcode_x1 = 72 create_Opcode_X1(JUMP_OPCODE_X1) | 73 create_JumpOpcodeExtension_X1(J_JUMP_OPCODE_X1) | 74 create_JumpOff_X1(pcrel_by_instr); 75 } 76 77 if (addr == FTRACE_ADDR) { 78 /* opcode: or r10, lr, zero */ 79 opcode_x0 = 80 create_Dest_X0(10) | 81 create_SrcA_X0(TREG_LR) | 82 create_SrcB_X0(TREG_ZERO) | 83 create_RRROpcodeExtension_X0(OR_RRR_0_OPCODE_X0) | 84 create_Opcode_X0(RRR_0_OPCODE_X0); 85 } else { 86 /* opcode: fnop */ 87 opcode_x0 = 88 create_UnaryOpcodeExtension_X0(FNOP_UNARY_OPCODE_X0) | 89 create_RRROpcodeExtension_X0(UNARY_RRR_0_OPCODE_X0) | 90 create_Opcode_X0(RRR_0_OPCODE_X0); 91 } 92 93 return opcode_x1 | opcode_x0; 94} 95 96static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) 97{ 98 return NOP(); 99} 100 101static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) 102{ 103 return ftrace_gen_branch(pc, addr, true); 104} 105 106static int ftrace_modify_code(unsigned long pc, unsigned long old, 107 unsigned long new) 108{ 109 unsigned long pc_wr; 110 111 /* Check if the address is in kernel text space and module space. */ 112 if (!kernel_text_address(pc)) 113 return -EINVAL; 114 115 /* Operate on writable kernel text mapping. */ 116 pc_wr = pc - MEM_SV_START + PAGE_OFFSET; 117 118 if (probe_kernel_write((void *)pc_wr, &new, MCOUNT_INSN_SIZE)) 119 return -EPERM; 120 121 smp_wmb(); 122 123 if (!machine_stopped && num_online_cpus() > 1) 124 flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); 125 126 return 0; 127} 128 129int ftrace_update_ftrace_func(ftrace_func_t func) 130{ 131 unsigned long pc, old; 132 unsigned long new; 133 int ret; 134 135 pc = (unsigned long)&ftrace_call; 136 memcpy(&old, &ftrace_call, MCOUNT_INSN_SIZE); 137 new = ftrace_call_replace(pc, (unsigned long)func); 138 139 ret = ftrace_modify_code(pc, old, new); 140 141 return ret; 142} 143 144int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 145{ 146 unsigned long new, old; 147 unsigned long ip = rec->ip; 148 149 old = ftrace_nop_replace(rec); 150 new = ftrace_call_replace(ip, addr); 151 152 return ftrace_modify_code(rec->ip, old, new); 153} 154 155int ftrace_make_nop(struct module *mod, 156 struct dyn_ftrace *rec, unsigned long addr) 157{ 158 unsigned long ip = rec->ip; 159 unsigned long old; 160 unsigned long new; 161 int ret; 162 163 old = ftrace_call_replace(ip, addr); 164 new = ftrace_nop_replace(rec); 165 ret = ftrace_modify_code(ip, old, new); 166 167 return ret; 168} 169 170int __init ftrace_dyn_arch_init(void) 171{ 172 return 0; 173} 174#endif /* CONFIG_DYNAMIC_FTRACE */ 175 176#ifdef CONFIG_FUNCTION_GRAPH_TRACER 177void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 178 unsigned long frame_pointer) 179{ 180 unsigned long return_hooker = (unsigned long) &return_to_handler; 181 struct ftrace_graph_ent trace; 182 unsigned long old; 183 int err; 184 185 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 186 return; 187 188 old = *parent; 189 *parent = return_hooker; 190 191 err = ftrace_push_return_trace(old, self_addr, &trace.depth, 192 frame_pointer); 193 if (err == -EBUSY) { 194 *parent = old; 195 return; 196 } 197 198 trace.func = self_addr; 199 200 /* Only trace if the calling function expects to */ 201 if (!ftrace_graph_entry(&trace)) { 202 current->curr_ret_stack--; 203 *parent = old; 204 } 205} 206 207#ifdef CONFIG_DYNAMIC_FTRACE 208extern unsigned long ftrace_graph_call; 209 210static int __ftrace_modify_caller(unsigned long *callsite, 211 void (*func) (void), bool enable) 212{ 213 unsigned long caller_fn = (unsigned long) func; 214 unsigned long pc = (unsigned long) callsite; 215 unsigned long branch = ftrace_gen_branch(pc, caller_fn, false); 216 unsigned long nop = NOP(); 217 unsigned long old = enable ? nop : branch; 218 unsigned long new = enable ? branch : nop; 219 220 return ftrace_modify_code(pc, old, new); 221} 222 223static int ftrace_modify_graph_caller(bool enable) 224{ 225 int ret; 226 227 ret = __ftrace_modify_caller(&ftrace_graph_call, 228 ftrace_graph_caller, 229 enable); 230 231 return ret; 232} 233 234int ftrace_enable_ftrace_graph_caller(void) 235{ 236 return ftrace_modify_graph_caller(true); 237} 238 239int ftrace_disable_ftrace_graph_caller(void) 240{ 241 return ftrace_modify_graph_caller(false); 242} 243#endif /* CONFIG_DYNAMIC_FTRACE */ 244#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 245