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 __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 ftrace_regs *fregs) 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, fregs); 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 int ftrace_update_ftrace_func(ftrace_func_t func) 98 { 99 return 0; 100 } 101 102 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 103 unsigned long addr) 104 { 105 return 0; 106 } 107 108 unsigned long ftrace_call_adjust(unsigned long addr) 109 { 110 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4; 111 } 112 113 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 114 { 115 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 116 u32 *tramp; 117 int size, ret, i; 118 void *ip; 119 120 #ifdef CONFIG_64BIT 121 unsigned long addr2 = 122 (unsigned long)dereference_function_descriptor((void *)addr); 123 124 u32 ftrace_trampoline[] = { 125 0x73c10208, /* std,ma r1,100(sp) */ 126 0x0c2110c1, /* ldd -10(r1),r1 */ 127 0xe820d002, /* bve,n (r1) */ 128 addr2 >> 32, 129 addr2 & 0xffffffff, 130 0xe83f1fd7, /* b,l,n .-14,r1 */ 131 }; 132 133 u32 ftrace_trampoline_unaligned[] = { 134 addr2 >> 32, 135 addr2 & 0xffffffff, 136 0x37de0200, /* ldo 100(sp),sp */ 137 0x73c13e01, /* std r1,-100(sp) */ 138 0x34213ff9, /* ldo -4(r1),r1 */ 139 0x50213fc1, /* ldd -20(r1),r1 */ 140 0xe820d002, /* bve,n (r1) */ 141 0xe83f1fcf, /* b,l,n .-20,r1 */ 142 }; 143 144 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) > 145 FTRACE_PATCHABLE_FUNCTION_SIZE); 146 #else 147 u32 ftrace_trampoline[] = { 148 (u32)addr, 149 0x6fc10080, /* stw,ma r1,40(sp) */ 150 0x48213fd1, /* ldw -18(r1),r1 */ 151 0xe820c002, /* bv,n r0(r1) */ 152 0xe83f1fdf, /* b,l,n .-c,r1 */ 153 }; 154 #endif 155 156 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) > 157 FTRACE_PATCHABLE_FUNCTION_SIZE); 158 159 size = sizeof(ftrace_trampoline); 160 tramp = ftrace_trampoline; 161 162 #ifdef CONFIG_64BIT 163 if (rec->ip & 0x4) { 164 size = sizeof(ftrace_trampoline_unaligned); 165 tramp = ftrace_trampoline_unaligned; 166 } 167 #endif 168 169 ip = (void *)(rec->ip + 4 - size); 170 171 ret = copy_from_kernel_nofault(insn, ip, size); 172 if (ret) 173 return ret; 174 175 for (i = 0; i < size / 4; i++) { 176 if (insn[i] != INSN_NOP) 177 return -EINVAL; 178 } 179 180 __patch_text_multiple(ip, tramp, size); 181 return 0; 182 } 183 184 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 185 unsigned long addr) 186 { 187 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 188 int i; 189 190 for (i = 0; i < ARRAY_SIZE(insn); i++) 191 insn[i] = INSN_NOP; 192 193 __patch_text((void *)rec->ip, INSN_NOP); 194 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn), 195 insn, sizeof(insn)-4); 196 return 0; 197 } 198 #endif 199 200 #ifdef CONFIG_KPROBES_ON_FTRACE 201 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 202 struct ftrace_ops *ops, struct ftrace_regs *fregs) 203 { 204 struct kprobe_ctlblk *kcb; 205 struct pt_regs *regs; 206 struct kprobe *p; 207 int bit; 208 209 bit = ftrace_test_recursion_trylock(ip, parent_ip); 210 if (bit < 0) 211 return; 212 213 regs = ftrace_get_regs(fregs); 214 preempt_disable_notrace(); 215 p = get_kprobe((kprobe_opcode_t *)ip); 216 if (unlikely(!p) || kprobe_disabled(p)) 217 goto out; 218 219 if (kprobe_running()) { 220 kprobes_inc_nmissed_count(p); 221 goto out; 222 } 223 224 __this_cpu_write(current_kprobe, p); 225 226 kcb = get_kprobe_ctlblk(); 227 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 228 229 regs->iaoq[0] = ip; 230 regs->iaoq[1] = ip + 4; 231 232 if (!p->pre_handler || !p->pre_handler(p, regs)) { 233 regs->iaoq[0] = ip + 4; 234 regs->iaoq[1] = ip + 8; 235 236 if (unlikely(p->post_handler)) { 237 kcb->kprobe_status = KPROBE_HIT_SSDONE; 238 p->post_handler(p, regs, 0); 239 } 240 } 241 __this_cpu_write(current_kprobe, NULL); 242 out: 243 preempt_enable_notrace(); 244 ftrace_test_recursion_unlock(bit); 245 } 246 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 247 248 int arch_prepare_kprobe_ftrace(struct kprobe *p) 249 { 250 p->ainsn.insn = NULL; 251 return 0; 252 } 253 #endif 254