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 (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub || 68 ftrace_graph_entry != ftrace_graph_entry_stub) { 69 unsigned long *parent_rp; 70 71 /* calculate pointer to %rp in stack */ 72 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET); 73 /* sanity check: parent_rp should hold parent */ 74 if (*parent_rp != parent) 75 return; 76 77 prepare_ftrace_return(parent_rp, self_addr); 78 return; 79 } 80 #endif 81 } 82 83 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 84 int ftrace_enable_ftrace_graph_caller(void) 85 { 86 return 0; 87 } 88 89 int ftrace_disable_ftrace_graph_caller(void) 90 { 91 return 0; 92 } 93 #endif 94 95 #ifdef CONFIG_DYNAMIC_FTRACE 96 97 int __init ftrace_dyn_arch_init(void) 98 { 99 return 0; 100 } 101 int ftrace_update_ftrace_func(ftrace_func_t func) 102 { 103 return 0; 104 } 105 106 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 107 unsigned long addr) 108 { 109 return 0; 110 } 111 112 unsigned long ftrace_call_adjust(unsigned long addr) 113 { 114 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4; 115 } 116 117 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 118 { 119 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 120 u32 *tramp; 121 int size, ret, i; 122 void *ip; 123 124 #ifdef CONFIG_64BIT 125 unsigned long addr2 = 126 (unsigned long)dereference_function_descriptor((void *)addr); 127 128 u32 ftrace_trampoline[] = { 129 0x73c10208, /* std,ma r1,100(sp) */ 130 0x0c2110c1, /* ldd -10(r1),r1 */ 131 0xe820d002, /* bve,n (r1) */ 132 addr2 >> 32, 133 addr2 & 0xffffffff, 134 0xe83f1fd7, /* b,l,n .-14,r1 */ 135 }; 136 137 u32 ftrace_trampoline_unaligned[] = { 138 addr2 >> 32, 139 addr2 & 0xffffffff, 140 0x37de0200, /* ldo 100(sp),sp */ 141 0x73c13e01, /* std r1,-100(sp) */ 142 0x34213ff9, /* ldo -4(r1),r1 */ 143 0x50213fc1, /* ldd -20(r1),r1 */ 144 0xe820d002, /* bve,n (r1) */ 145 0xe83f1fcf, /* b,l,n .-20,r1 */ 146 }; 147 148 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) > 149 FTRACE_PATCHABLE_FUNCTION_SIZE); 150 #else 151 u32 ftrace_trampoline[] = { 152 (u32)addr, 153 0x6fc10080, /* stw,ma r1,40(sp) */ 154 0x48213fd1, /* ldw -18(r1),r1 */ 155 0xe820c002, /* bv,n r0(r1) */ 156 0xe83f1fdf, /* b,l,n .-c,r1 */ 157 }; 158 #endif 159 160 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) > 161 FTRACE_PATCHABLE_FUNCTION_SIZE); 162 163 size = sizeof(ftrace_trampoline); 164 tramp = ftrace_trampoline; 165 166 #ifdef CONFIG_64BIT 167 if (rec->ip & 0x4) { 168 size = sizeof(ftrace_trampoline_unaligned); 169 tramp = ftrace_trampoline_unaligned; 170 } 171 #endif 172 173 ip = (void *)(rec->ip + 4 - size); 174 175 ret = probe_kernel_read(insn, ip, size); 176 if (ret) 177 return ret; 178 179 for (i = 0; i < size / 4; i++) { 180 if (insn[i] != INSN_NOP) 181 return -EINVAL; 182 } 183 184 __patch_text_multiple(ip, tramp, size); 185 return 0; 186 } 187 188 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 189 unsigned long addr) 190 { 191 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 192 int i; 193 194 for (i = 0; i < ARRAY_SIZE(insn); i++) 195 insn[i] = INSN_NOP; 196 197 __patch_text((void *)rec->ip, INSN_NOP); 198 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn), 199 insn, sizeof(insn)-4); 200 return 0; 201 } 202 #endif 203 204 #ifdef CONFIG_KPROBES_ON_FTRACE 205 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 206 struct ftrace_ops *ops, struct pt_regs *regs) 207 { 208 struct kprobe_ctlblk *kcb; 209 struct kprobe *p = get_kprobe((kprobe_opcode_t *)ip); 210 211 if (unlikely(!p) || kprobe_disabled(p)) 212 return; 213 214 if (kprobe_running()) { 215 kprobes_inc_nmissed_count(p); 216 return; 217 } 218 219 __this_cpu_write(current_kprobe, p); 220 221 kcb = get_kprobe_ctlblk(); 222 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 223 224 regs->iaoq[0] = ip; 225 regs->iaoq[1] = ip + 4; 226 227 if (!p->pre_handler || !p->pre_handler(p, regs)) { 228 regs->iaoq[0] = ip + 4; 229 regs->iaoq[1] = ip + 8; 230 231 if (unlikely(p->post_handler)) { 232 kcb->kprobe_status = KPROBE_HIT_SSDONE; 233 p->post_handler(p, regs, 0); 234 } 235 } 236 __this_cpu_write(current_kprobe, NULL); 237 } 238 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 239 240 int arch_prepare_kprobe_ftrace(struct kprobe *p) 241 { 242 p->ainsn.insn = NULL; 243 return 0; 244 } 245 #endif 246