1 /* 2 * Ftrace support for Microblaze. 3 * 4 * Copyright (C) 2009 Michal Simek <monstr@monstr.eu> 5 * Copyright (C) 2009 PetaLogix 6 * 7 * Based on MIPS and PowerPC ftrace code 8 * 9 * This file is subject to the terms and conditions of the GNU General Public 10 * License. See the file "COPYING" in the main directory of this archive 11 * for more details. 12 */ 13 14 #include <asm/cacheflush.h> 15 #include <linux/ftrace.h> 16 17 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 18 /* 19 * Hook the return address and push it in the stack of return addrs 20 * in current thread info. 21 */ 22 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr) 23 { 24 unsigned long old; 25 int faulted; 26 unsigned long return_hooker = (unsigned long) 27 &return_to_handler; 28 29 if (unlikely(ftrace_graph_is_dead())) 30 return; 31 32 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 33 return; 34 35 /* 36 * Protect against fault, even if it shouldn't 37 * happen. This tool is too much intrusive to 38 * ignore such a protection. 39 */ 40 asm volatile(" 1: lwi %0, %2, 0;" \ 41 "2: swi %3, %2, 0;" \ 42 " addik %1, r0, 0;" \ 43 "3:" \ 44 " .section .fixup, \"ax\";" \ 45 "4: brid 3b;" \ 46 " addik %1, r0, 1;" \ 47 " .previous;" \ 48 " .section __ex_table,\"a\";" \ 49 " .word 1b,4b;" \ 50 " .word 2b,4b;" \ 51 " .previous;" \ 52 : "=&r" (old), "=r" (faulted) 53 : "r" (parent), "r" (return_hooker) 54 ); 55 56 flush_dcache_range((u32)parent, (u32)parent + 4); 57 flush_icache_range((u32)parent, (u32)parent + 4); 58 59 if (unlikely(faulted)) { 60 ftrace_graph_stop(); 61 WARN_ON(1); 62 return; 63 } 64 65 if (function_graph_enter(old, self_addr, 0, NULL)) 66 *parent = old; 67 } 68 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 69 70 #ifdef CONFIG_DYNAMIC_FTRACE 71 /* save value to addr - it is save to do it in asm */ 72 static int ftrace_modify_code(unsigned long addr, unsigned int value) 73 { 74 int faulted = 0; 75 76 __asm__ __volatile__(" 1: swi %2, %1, 0;" \ 77 " addik %0, r0, 0;" \ 78 "2:" \ 79 " .section .fixup, \"ax\";" \ 80 "3: brid 2b;" \ 81 " addik %0, r0, 1;" \ 82 " .previous;" \ 83 " .section __ex_table,\"a\";" \ 84 " .word 1b,3b;" \ 85 " .previous;" \ 86 : "=r" (faulted) 87 : "r" (addr), "r" (value) 88 ); 89 90 if (unlikely(faulted)) 91 return -EFAULT; 92 93 flush_dcache_range(addr, addr + 4); 94 flush_icache_range(addr, addr + 4); 95 96 return 0; 97 } 98 99 #define MICROBLAZE_NOP 0x80000000 100 #define MICROBLAZE_BRI 0xb800000C 101 102 static unsigned int recorded; /* if save was or not */ 103 static unsigned int imm; /* saving whole imm instruction */ 104 105 /* There are two approaches howto solve ftrace_make nop function - look below */ 106 #undef USE_FTRACE_NOP 107 108 #ifdef USE_FTRACE_NOP 109 static unsigned int bralid; /* saving whole bralid instruction */ 110 #endif 111 112 int ftrace_make_nop(struct module *mod, 113 struct dyn_ftrace *rec, unsigned long addr) 114 { 115 /* we have this part of code which we are working with 116 * b000c000 imm -16384 117 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 118 * 80000000 or r0, r0, r0 119 * 120 * The first solution (!USE_FTRACE_NOP-could be called branch solution) 121 * b000c000 bri 12 (0xC - jump to any other instruction) 122 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 123 * 80000000 or r0, r0, r0 124 * any other instruction 125 * 126 * The second solution (USE_FTRACE_NOP) - no jump just nops 127 * 80000000 or r0, r0, r0 128 * 80000000 or r0, r0, r0 129 * 80000000 or r0, r0, r0 130 */ 131 int ret = 0; 132 133 if (recorded == 0) { 134 recorded = 1; 135 imm = *(unsigned int *)rec->ip; 136 pr_debug("%s: imm:0x%x\n", __func__, imm); 137 #ifdef USE_FTRACE_NOP 138 bralid = *(unsigned int *)(rec->ip + 4); 139 pr_debug("%s: bralid 0x%x\n", __func__, bralid); 140 #endif /* USE_FTRACE_NOP */ 141 } 142 143 #ifdef USE_FTRACE_NOP 144 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP); 145 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP); 146 #else /* USE_FTRACE_NOP */ 147 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI); 148 #endif /* USE_FTRACE_NOP */ 149 return ret; 150 } 151 152 /* I believe that first is called ftrace_make_nop before this function */ 153 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 154 { 155 int ret; 156 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n", 157 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); 158 ret = ftrace_modify_code(rec->ip, imm); 159 #ifdef USE_FTRACE_NOP 160 pr_debug("%s: bralid:0x%x\n", __func__, bralid); 161 ret += ftrace_modify_code(rec->ip + 4, bralid); 162 #endif /* USE_FTRACE_NOP */ 163 return ret; 164 } 165 166 int __init ftrace_dyn_arch_init(void) 167 { 168 return 0; 169 } 170 171 int ftrace_update_ftrace_func(ftrace_func_t func) 172 { 173 unsigned long ip = (unsigned long)(&ftrace_call); 174 unsigned int upper = (unsigned int)func; 175 unsigned int lower = (unsigned int)func; 176 int ret = 0; 177 178 /* create proper saving to ftrace_call poll */ 179 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */ 180 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */ 181 182 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n", 183 __func__, (unsigned int)func, (unsigned int)ip, upper, lower); 184 185 /* save upper and lower code */ 186 ret = ftrace_modify_code(ip, upper); 187 ret += ftrace_modify_code(ip + 4, lower); 188 189 /* We just need to replace the rtsd r15, 8 with NOP */ 190 ret += ftrace_modify_code((unsigned long)&ftrace_caller, 191 MICROBLAZE_NOP); 192 193 return ret; 194 } 195 196 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 197 unsigned int old_jump; /* saving place for jump instruction */ 198 199 int ftrace_enable_ftrace_graph_caller(void) 200 { 201 unsigned int ret; 202 unsigned long ip = (unsigned long)(&ftrace_call_graph); 203 204 old_jump = *(unsigned int *)ip; /* save jump over instruction */ 205 ret = ftrace_modify_code(ip, MICROBLAZE_NOP); 206 207 pr_debug("%s: Replace instruction: 0x%x\n", __func__, old_jump); 208 return ret; 209 } 210 211 int ftrace_disable_ftrace_graph_caller(void) 212 { 213 unsigned int ret; 214 unsigned long ip = (unsigned long)(&ftrace_call_graph); 215 216 ret = ftrace_modify_code(ip, old_jump); 217 218 pr_debug("%s\n", __func__); 219 return ret; 220 } 221 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 222 #endif /* CONFIG_DYNAMIC_FTRACE */ 223