1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Code for tracing calls in Linux kernel. 4 * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de> 5 * 6 * based on code for x86 which is: 7 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> 8 * 9 * future possible enhancements: 10 * - add CONFIG_STACK_TRACER 11 */ 12 13 #include <linux/init.h> 14 #include <linux/ftrace.h> 15 #include <linux/uaccess.h> 16 17 #include <asm/assembly.h> 18 #include <asm/sections.h> 19 #include <asm/ftrace.h> 20 #include <asm/patch.h> 21 22 #define __hot __attribute__ ((__section__ (".text.hot"))) 23 24 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 25 /* 26 * Hook the return address and push it in the stack of return addrs 27 * in current thread info. 28 */ 29 static void __hot prepare_ftrace_return(unsigned long *parent, 30 unsigned long self_addr) 31 { 32 unsigned long old; 33 extern int parisc_return_to_handler; 34 35 if (unlikely(ftrace_graph_is_dead())) 36 return; 37 38 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 39 return; 40 41 old = *parent; 42 43 if (!function_graph_enter(old, self_addr, 0, NULL)) 44 /* activate parisc_return_to_handler() as return point */ 45 *parent = (unsigned long) &parisc_return_to_handler; 46 } 47 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 48 49 void notrace __hot ftrace_function_trampoline(unsigned long parent, 50 unsigned long self_addr, 51 unsigned long org_sp_gr3) 52 { 53 #ifndef CONFIG_DYNAMIC_FTRACE 54 extern ftrace_func_t ftrace_trace_function; 55 #endif 56 if (ftrace_trace_function != ftrace_stub) 57 ftrace_trace_function(self_addr, parent, NULL, NULL); 58 59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 60 if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub || 61 ftrace_graph_entry != ftrace_graph_entry_stub) { 62 unsigned long *parent_rp; 63 64 /* calculate pointer to %rp in stack */ 65 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET); 66 /* sanity check: parent_rp should hold parent */ 67 if (*parent_rp != parent) 68 return; 69 70 prepare_ftrace_return(parent_rp, self_addr); 71 return; 72 } 73 #endif 74 } 75 76 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 77 int ftrace_enable_ftrace_graph_caller(void) 78 { 79 return 0; 80 } 81 82 int ftrace_disable_ftrace_graph_caller(void) 83 { 84 return 0; 85 } 86 #endif 87 88 #ifdef CONFIG_DYNAMIC_FTRACE 89 90 int __init ftrace_dyn_arch_init(void) 91 { 92 return 0; 93 } 94 int ftrace_update_ftrace_func(ftrace_func_t func) 95 { 96 return 0; 97 } 98 99 unsigned long ftrace_call_adjust(unsigned long addr) 100 { 101 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4; 102 } 103 104 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 105 { 106 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 107 u32 *tramp; 108 int size, ret, i; 109 void *ip; 110 111 #ifdef CONFIG_64BIT 112 unsigned long addr2 = 113 (unsigned long)dereference_function_descriptor((void *)addr); 114 115 u32 ftrace_trampoline[] = { 116 0x73c10208, /* std,ma r1,100(sp) */ 117 0x0c2110c1, /* ldd -10(r1),r1 */ 118 0xe820d002, /* bve,n (r1) */ 119 addr2 >> 32, 120 addr2 & 0xffffffff, 121 0xe83f1fd7, /* b,l,n .-14,r1 */ 122 }; 123 124 u32 ftrace_trampoline_unaligned[] = { 125 addr2 >> 32, 126 addr2 & 0xffffffff, 127 0x37de0200, /* ldo 100(sp),sp */ 128 0x73c13e01, /* std r1,-100(sp) */ 129 0x34213ff9, /* ldo -4(r1),r1 */ 130 0x50213fc1, /* ldd -20(r1),r1 */ 131 0xe820d002, /* bve,n (r1) */ 132 0xe83f1fcf, /* b,l,n .-20,r1 */ 133 }; 134 135 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) > 136 FTRACE_PATCHABLE_FUNCTION_SIZE); 137 #else 138 u32 ftrace_trampoline[] = { 139 (u32)addr, 140 0x6fc10080, /* stw,ma r1,40(sp) */ 141 0x48213fd1, /* ldw -18(r1),r1 */ 142 0xe820c002, /* bv,n r0(r1) */ 143 0xe83f1fdf, /* b,l,n .-c,r1 */ 144 }; 145 #endif 146 147 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) > 148 FTRACE_PATCHABLE_FUNCTION_SIZE); 149 150 size = sizeof(ftrace_trampoline); 151 tramp = ftrace_trampoline; 152 153 #ifdef CONFIG_64BIT 154 if (rec->ip & 0x4) { 155 size = sizeof(ftrace_trampoline_unaligned); 156 tramp = ftrace_trampoline_unaligned; 157 } 158 #endif 159 160 ip = (void *)(rec->ip + 4 - size); 161 162 ret = probe_kernel_read(insn, ip, size); 163 if (ret) 164 return ret; 165 166 for (i = 0; i < size / 4; i++) { 167 if (insn[i] != INSN_NOP) 168 return -EINVAL; 169 } 170 171 __patch_text_multiple(ip, tramp, size); 172 return 0; 173 } 174 175 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 176 unsigned long addr) 177 { 178 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 179 int i; 180 181 for (i = 0; i < ARRAY_SIZE(insn); i++) 182 insn[i] = INSN_NOP; 183 184 __patch_text((void *)rec->ip, INSN_NOP); 185 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn), 186 insn, sizeof(insn)-4); 187 return 0; 188 } 189 #endif 190