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_DYNAMIC_FTRACE 18 /* save value to addr - it is save to do it in asm */ 19 static int ftrace_modify_code(unsigned long addr, unsigned int value) 20 { 21 int faulted = 0; 22 23 __asm__ __volatile__(" 1: swi %2, %1, 0; \ 24 addik %0, r0, 0; \ 25 2: \ 26 .section .fixup, \"ax\"; \ 27 3: brid 2b; \ 28 addik %0, r0, 1; \ 29 .previous; \ 30 .section __ex_table,\"a\"; \ 31 .word 1b,3b; \ 32 .previous;" \ 33 : "=r" (faulted) 34 : "r" (addr), "r" (value) 35 ); 36 37 if (unlikely(faulted)) 38 return -EFAULT; 39 40 return 0; 41 } 42 43 #define MICROBLAZE_NOP 0x80000000 44 #define MICROBLAZE_BRI 0xb800000C 45 46 static unsigned int recorded; /* if save was or not */ 47 static unsigned int imm; /* saving whole imm instruction */ 48 49 /* There are two approaches howto solve ftrace_make nop function - look below */ 50 #undef USE_FTRACE_NOP 51 52 #ifdef USE_FTRACE_NOP 53 static unsigned int bralid; /* saving whole bralid instruction */ 54 #endif 55 56 int ftrace_make_nop(struct module *mod, 57 struct dyn_ftrace *rec, unsigned long addr) 58 { 59 /* we have this part of code which we are working with 60 * b000c000 imm -16384 61 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 62 * 80000000 or r0, r0, r0 63 * 64 * The first solution (!USE_FTRACE_NOP-could be called branch solution) 65 * b000c000 bri 12 (0xC - jump to any other instruction) 66 * b9fc8e30 bralid r15, -29136 // c0008e30 <_mcount> 67 * 80000000 or r0, r0, r0 68 * any other instruction 69 * 70 * The second solution (USE_FTRACE_NOP) - no jump just nops 71 * 80000000 or r0, r0, r0 72 * 80000000 or r0, r0, r0 73 * 80000000 or r0, r0, r0 74 */ 75 int ret = 0; 76 77 if (recorded == 0) { 78 recorded = 1; 79 imm = *(unsigned int *)rec->ip; 80 pr_debug("%s: imm:0x%x\n", __func__, imm); 81 #ifdef USE_FTRACE_NOP 82 bralid = *(unsigned int *)(rec->ip + 4); 83 pr_debug("%s: bralid 0x%x\n", __func__, bralid); 84 #endif /* USE_FTRACE_NOP */ 85 } 86 87 #ifdef USE_FTRACE_NOP 88 ret = ftrace_modify_code(rec->ip, MICROBLAZE_NOP); 89 ret += ftrace_modify_code(rec->ip + 4, MICROBLAZE_NOP); 90 #else /* USE_FTRACE_NOP */ 91 ret = ftrace_modify_code(rec->ip, MICROBLAZE_BRI); 92 #endif /* USE_FTRACE_NOP */ 93 return ret; 94 } 95 96 static int ret_addr; /* initialized as 0 by default */ 97 98 /* I believe that first is called ftrace_make_nop before this function */ 99 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 100 { 101 int ret; 102 ret_addr = addr; /* saving where the barrier jump is */ 103 pr_debug("%s: addr:0x%x, rec->ip: 0x%x, imm:0x%x\n", 104 __func__, (unsigned int)addr, (unsigned int)rec->ip, imm); 105 ret = ftrace_modify_code(rec->ip, imm); 106 #ifdef USE_FTRACE_NOP 107 pr_debug("%s: bralid:0x%x\n", __func__, bralid); 108 ret += ftrace_modify_code(rec->ip + 4, bralid); 109 #endif /* USE_FTRACE_NOP */ 110 return ret; 111 } 112 113 int __init ftrace_dyn_arch_init(void *data) 114 { 115 /* The return code is retured via data */ 116 *(unsigned long *)data = 0; 117 118 return 0; 119 } 120 121 int ftrace_update_ftrace_func(ftrace_func_t func) 122 { 123 unsigned long ip = (unsigned long)(&ftrace_call); 124 unsigned int upper = (unsigned int)func; 125 unsigned int lower = (unsigned int)func; 126 int ret = 0; 127 128 /* create proper saving to ftrace_call poll */ 129 upper = 0xb0000000 + (upper >> 16); /* imm func_upper */ 130 lower = 0x32800000 + (lower & 0xFFFF); /* addik r20, r0, func_lower */ 131 132 pr_debug("%s: func=0x%x, ip=0x%x, upper=0x%x, lower=0x%x\n", 133 __func__, (unsigned int)func, (unsigned int)ip, upper, lower); 134 135 /* save upper and lower code */ 136 ret = ftrace_modify_code(ip, upper); 137 ret += ftrace_modify_code(ip + 4, lower); 138 139 /* We just need to remove the rtsd r15, 8 by NOP */ 140 BUG_ON(!ret_addr); 141 if (ret_addr) 142 ret += ftrace_modify_code(ret_addr, MICROBLAZE_NOP); 143 else 144 ret = 1; /* fault */ 145 146 /* All changes are done - lets do caches consistent */ 147 flush_icache(); 148 return ret; 149 } 150 151 #endif /* CONFIG_DYNAMIC_FTRACE */ 152