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 #include <linux/kprobes.h> 17 #include <linux/ptrace.h> 18 19 #include <asm/assembly.h> 20 #include <asm/sections.h> 21 #include <asm/ftrace.h> 22 #include <asm/patch.h> 23 24 #define __hot __attribute__ ((__section__ (".text.hot"))) 25 26 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 27 /* 28 * Hook the return address and push it in the stack of return addrs 29 * in current thread info. 30 */ 31 static void __hot prepare_ftrace_return(unsigned long *parent, 32 unsigned long self_addr) 33 { 34 unsigned long old; 35 extern int parisc_return_to_handler; 36 37 if (unlikely(ftrace_graph_is_dead())) 38 return; 39 40 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 41 return; 42 43 old = *parent; 44 45 if (!function_graph_enter(old, self_addr, 0, NULL)) 46 /* activate parisc_return_to_handler() as return point */ 47 *parent = (unsigned long) &parisc_return_to_handler; 48 } 49 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 50 51 void notrace __hot ftrace_function_trampoline(unsigned long parent, 52 unsigned long self_addr, 53 unsigned long org_sp_gr3, 54 struct pt_regs *regs) 55 { 56 #ifndef CONFIG_DYNAMIC_FTRACE 57 extern ftrace_func_t ftrace_trace_function; 58 #endif 59 extern struct ftrace_ops *function_trace_op; 60 61 if (function_trace_op->flags & FTRACE_OPS_FL_ENABLED && 62 ftrace_trace_function != ftrace_stub) 63 ftrace_trace_function(self_addr, parent, 64 function_trace_op, regs); 65 66 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 67 if (dereference_function_descriptor(ftrace_graph_return) != 68 dereference_function_descriptor(ftrace_stub) || 69 ftrace_graph_entry != ftrace_graph_entry_stub) { 70 unsigned long *parent_rp; 71 72 /* calculate pointer to %rp in stack */ 73 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET); 74 /* sanity check: parent_rp should hold parent */ 75 if (*parent_rp != parent) 76 return; 77 78 prepare_ftrace_return(parent_rp, self_addr); 79 return; 80 } 81 #endif 82 } 83 84 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 85 int ftrace_enable_ftrace_graph_caller(void) 86 { 87 return 0; 88 } 89 90 int ftrace_disable_ftrace_graph_caller(void) 91 { 92 return 0; 93 } 94 #endif 95 96 #ifdef CONFIG_DYNAMIC_FTRACE 97 98 int __init ftrace_dyn_arch_init(void) 99 { 100 return 0; 101 } 102 int ftrace_update_ftrace_func(ftrace_func_t func) 103 { 104 return 0; 105 } 106 107 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 108 unsigned long addr) 109 { 110 return 0; 111 } 112 113 unsigned long ftrace_call_adjust(unsigned long addr) 114 { 115 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4; 116 } 117 118 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 119 { 120 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 121 u32 *tramp; 122 int size, ret, i; 123 void *ip; 124 125 #ifdef CONFIG_64BIT 126 unsigned long addr2 = 127 (unsigned long)dereference_function_descriptor((void *)addr); 128 129 u32 ftrace_trampoline[] = { 130 0x73c10208, /* std,ma r1,100(sp) */ 131 0x0c2110c1, /* ldd -10(r1),r1 */ 132 0xe820d002, /* bve,n (r1) */ 133 addr2 >> 32, 134 addr2 & 0xffffffff, 135 0xe83f1fd7, /* b,l,n .-14,r1 */ 136 }; 137 138 u32 ftrace_trampoline_unaligned[] = { 139 addr2 >> 32, 140 addr2 & 0xffffffff, 141 0x37de0200, /* ldo 100(sp),sp */ 142 0x73c13e01, /* std r1,-100(sp) */ 143 0x34213ff9, /* ldo -4(r1),r1 */ 144 0x50213fc1, /* ldd -20(r1),r1 */ 145 0xe820d002, /* bve,n (r1) */ 146 0xe83f1fcf, /* b,l,n .-20,r1 */ 147 }; 148 149 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) > 150 FTRACE_PATCHABLE_FUNCTION_SIZE); 151 #else 152 u32 ftrace_trampoline[] = { 153 (u32)addr, 154 0x6fc10080, /* stw,ma r1,40(sp) */ 155 0x48213fd1, /* ldw -18(r1),r1 */ 156 0xe820c002, /* bv,n r0(r1) */ 157 0xe83f1fdf, /* b,l,n .-c,r1 */ 158 }; 159 #endif 160 161 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) > 162 FTRACE_PATCHABLE_FUNCTION_SIZE); 163 164 size = sizeof(ftrace_trampoline); 165 tramp = ftrace_trampoline; 166 167 #ifdef CONFIG_64BIT 168 if (rec->ip & 0x4) { 169 size = sizeof(ftrace_trampoline_unaligned); 170 tramp = ftrace_trampoline_unaligned; 171 } 172 #endif 173 174 ip = (void *)(rec->ip + 4 - size); 175 176 ret = copy_from_kernel_nofault(insn, ip, size); 177 if (ret) 178 return ret; 179 180 for (i = 0; i < size / 4; i++) { 181 if (insn[i] != INSN_NOP) 182 return -EINVAL; 183 } 184 185 __patch_text_multiple(ip, tramp, size); 186 return 0; 187 } 188 189 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 190 unsigned long addr) 191 { 192 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 193 int i; 194 195 for (i = 0; i < ARRAY_SIZE(insn); i++) 196 insn[i] = INSN_NOP; 197 198 __patch_text((void *)rec->ip, INSN_NOP); 199 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn), 200 insn, sizeof(insn)-4); 201 return 0; 202 } 203 #endif 204 205 #ifdef CONFIG_KPROBES_ON_FTRACE 206 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 207 struct ftrace_ops *ops, struct pt_regs *regs) 208 { 209 struct kprobe_ctlblk *kcb; 210 struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip); 211 212 if (unlikely(!p) || kprobe_disabled(p)) 213 return; 214 215 if (kprobe_running()) { 216 kprobes_inc_nmissed_count(p); 217 return; 218 } 219 220 __this_cpu_write(current_kprobe, p); 221 222 kcb = get_kprobe_ctlblk(); 223 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 224 225 regs->iaoq[0] = ip; 226 regs->iaoq[1] = ip + 4; 227 228 if (!p->pre_handler || !p->pre_handler(p, regs)) { 229 regs->iaoq[0] = ip + 4; 230 regs->iaoq[1] = ip + 8; 231 232 if (unlikely(p->post_handler)) { 233 kcb->kprobe_status = KPROBE_HIT_SSDONE; 234 p->post_handler(p, regs, 0); 235 } 236 } 237 __this_cpu_write(current_kprobe, NULL); 238 } 239 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 240 241 int arch_prepare_kprobe_ftrace(struct kprobe *p) 242 { 243 p->ainsn.insn = NULL; 244 return 0; 245 } 246 #endif 247