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, err; 26 struct ftrace_graph_ent trace; 27 unsigned long return_hooker = (unsigned long) 28 &return_to_handler; 29 30 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 31 return; 32 33 /* 34 * Protect against fault, even if it shouldn't 35 * happen. This tool is too much intrusive to 36 * ignore such a protection. 37 */ 38 asm volatile(" 1: lwi %0, %2, 0; \ 39 2: swi %3, %2, 0; \ 40 addik %1, r0, 0; \ 41 3: \ 42 .section .fixup, \"ax\"; \ 43 4: brid 3b; \ 44 addik %1, r0, 1; \ 45 .previous; \ 46 .section __ex_table,\"a\"; \ 47 .word 1b,4b; \ 48 .word 2b,4b; \ 49 .previous;" \ 50 : "=&r" (old), "=r" (faulted) 51 : "r" (parent), "r" (return_hooker) 52 ); 53 54 if (unlikely(faulted)) { 55 ftrace_graph_stop(); 56 WARN_ON(1); 57 return; 58 } 59 60 err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0); 61 if (err == -EBUSY) { 62 *parent = old; 63 return; 64 } 65 66 trace.func = self_addr; 67 /* Only trace if the calling function expects to */ 68 if (!ftrace_graph_entry(&trace)) { 69 current->curr_ret_stack--; 70 *parent = old; 71 } 72 } 73 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 74 75 #ifdef CONFIG_DYNAMIC_FTRACE 76 /* save value to addr - it is save to do it in asm */ 77 static int ftrace_modify_code(unsigned long addr, unsigned int value) 78 { 79 int faulted = 0; 80 81 __asm__ __volatile__(" 1: swi %2, %1, 0; \ 82 addik %0, r0, 0; \ 83 2: \ 84 .section .fixup, \"ax\"; \ 85 3: brid 2b; \ 86 addik %0, r0, 1; \ 87 .previous; \ 88 .section __ex_table,\"a\"; \ 89 .word 1b,3b; \ 90 .previous;" \ 91 : "=r" (faulted) 92 : "r" (addr), "r" (value) 93 ); 94 95 if (unlikely(faulted)) 96 return -EFAULT; 97 98 return 0; 99 } 100 101 #define MICROBLAZE_NOP 0x80000000 102 #define MICROBLAZE_BRI 0xb800000C 103 104 static unsigned int recorded; /* if save was or not */ 105 static unsigned int imm; /* saving whole imm instruction */ 106 107 /* There are two approaches howto solve ftrace_make nop function - look below */ 108 #undef USE_FTRACE_NOP 109 110 #ifdef USE_FTRACE_NOP 111 static unsigned int bralid; /* saving whole bralid instruction */ 112 #endif 113 114 int ftrace_make_nop(struct module *mod, 115 struct dyn_ftrace *rec, unsigned long addr) 116 { 117 /* we have this part of code which we are working with 118 * b000c000 imm -16384 119 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 120 * 80000000 or r0, r0, r0 121 * 122 * The first solution (!USE_FTRACE_NOP-could be called branch solution) 123 * b000c000 bri 12 (0xC - jump to any other instruction) 124 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 125 * 80000000 or r0, r0, r0 126 * any other instruction 127 * 128 * The second solution (USE_FTRACE_NOP) - no jump just nops 129 * 80000000 or r0, r0, r0 130 * 80000000 or r0, r0, r0 131 * 80000000 or r0, r0, r0 132 */ 133 int ret = 0; 134 135 if (recorded == 0) { 136 recorded = 1; 137 imm = *(unsigned int *)rec->ip; 138 pr_debug("%s: imm:0x%x\n", __func__, imm); 139 #ifdef USE_FTRACE_NOP 140 bralid = *(unsigned int *)(rec->ip + 4); 141 pr_debug("%s: bralid 0x%x\n", __func__, bralid); 142 #endif /* USE_FTRACE_NOP */ 143 } 144 145 #ifdef USE_FTRACE_NOP 146 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP); 147 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP); 148 #else /* USE_FTRACE_NOP */ 149 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI); 150 #endif /* USE_FTRACE_NOP */ 151 return ret; 152 } 153 154 static int ret_addr; /* initialized as 0 by default */ 155 156 /* I believe that first is called ftrace_make_nop before this function */ 157 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 158 { 159 int ret; 160 ret_addr = addr; /* saving where the barrier jump is */ 161 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n", 162 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); 163 ret = ftrace_modify_code(rec->ip, imm); 164 #ifdef USE_FTRACE_NOP 165 pr_debug("%s: bralid:0x%x\n", __func__, bralid); 166 ret += ftrace_modify_code(rec->ip + 4, bralid); 167 #endif /* USE_FTRACE_NOP */ 168 return ret; 169 } 170 171 int __init ftrace_dyn_arch_init(void *data) 172 { 173 /* The return code is retured via data */ 174 *(unsigned long *)data = 0; 175 176 return 0; 177 } 178 179 int ftrace_update_ftrace_func(ftrace_func_t func) 180 { 181 unsigned long ip = (unsigned long)(&ftrace_call); 182 unsigned int upper = (unsigned int)func; 183 unsigned int lower = (unsigned int)func; 184 int ret = 0; 185 186 /* create proper saving to ftrace_call poll */ 187 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */ 188 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */ 189 190 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n", 191 __func__, (unsigned int)func, (unsigned int)ip, upper, lower); 192 193 /* save upper and lower code */ 194 ret = ftrace_modify_code(ip, upper); 195 ret += ftrace_modify_code(ip + 4, lower); 196 197 /* We just need to remove the rtsd r15, 8 by NOP */ 198 BUG_ON(!ret_addr); 199 if (ret_addr) 200 ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP); 201 else 202 ret = 1; /* fault */ 203 204 /* All changes are done - lets do caches consistent */ 205 flush_icache(); 206 return ret; 207 } 208 209 #endif /* CONFIG_DYNAMIC_FTRACE */ 210