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 #include <linux/jump_label.h> 19 20 #include <asm/assembly.h> 21 #include <asm/sections.h> 22 #include <asm/ftrace.h> 23 #include <asm/patch.h> 24 25 #define __hot __section(".text.hot") 26 27 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 28 static DEFINE_STATIC_KEY_FALSE(ftrace_graph_enable); 29 30 /* 31 * Hook the return address and push it in the stack of return addrs 32 * in current thread info. 33 */ 34 static void __hot prepare_ftrace_return(unsigned long *parent, 35 unsigned long self_addr) 36 { 37 unsigned long old; 38 extern int parisc_return_to_handler; 39 40 if (unlikely(ftrace_graph_is_dead())) 41 return; 42 43 if (unlikely(atomic_read(¤t->tracing_graph_pause))) 44 return; 45 46 old = *parent; 47 48 if (!function_graph_enter(old, self_addr, 0, NULL)) 49 /* activate parisc_return_to_handler() as return point */ 50 *parent = (unsigned long) &parisc_return_to_handler; 51 } 52 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 53 54 static ftrace_func_t ftrace_func; 55 56 asmlinkage void notrace __hot ftrace_function_trampoline(unsigned long parent, 57 unsigned long self_addr, 58 unsigned long org_sp_gr3, 59 struct ftrace_regs *fregs) 60 { 61 extern struct ftrace_ops *function_trace_op; 62 63 ftrace_func(self_addr, parent, function_trace_op, fregs); 64 65 #ifdef CONFIG_FUNCTION_GRAPH_TRACER 66 if (static_branch_unlikely(&ftrace_graph_enable)) { 67 unsigned long *parent_rp; 68 69 /* calculate pointer to %rp in stack */ 70 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET); 71 /* sanity check: parent_rp should hold parent */ 72 if (*parent_rp != parent) 73 return; 74 75 prepare_ftrace_return(parent_rp, self_addr); 76 return; 77 } 78 #endif 79 } 80 81 #if defined(CONFIG_DYNAMIC_FTRACE) && defined(CONFIG_FUNCTION_GRAPH_TRACER) 82 int ftrace_enable_ftrace_graph_caller(void) 83 { 84 static_key_enable(&ftrace_graph_enable.key); 85 return 0; 86 } 87 88 int ftrace_disable_ftrace_graph_caller(void) 89 { 90 static_key_enable(&ftrace_graph_enable.key); 91 return 0; 92 } 93 #endif 94 95 #ifdef CONFIG_DYNAMIC_FTRACE 96 int ftrace_update_ftrace_func(ftrace_func_t func) 97 { 98 ftrace_func = func; 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 if (unlikely(kprobe_ftrace_disabled)) 210 return; 211 212 bit = ftrace_test_recursion_trylock(ip, parent_ip); 213 if (bit < 0) 214 return; 215 216 regs = ftrace_get_regs(fregs); 217 p = get_kprobe((kprobe_opcode_t *)ip); 218 if (unlikely(!p) || kprobe_disabled(p)) 219 goto out; 220 221 if (kprobe_running()) { 222 kprobes_inc_nmissed_count(p); 223 goto out; 224 } 225 226 __this_cpu_write(current_kprobe, p); 227 228 kcb = get_kprobe_ctlblk(); 229 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 230 231 regs->iaoq[0] = ip; 232 regs->iaoq[1] = ip + 4; 233 234 if (!p->pre_handler || !p->pre_handler(p, regs)) { 235 regs->iaoq[0] = ip + 4; 236 regs->iaoq[1] = ip + 8; 237 238 if (unlikely(p->post_handler)) { 239 kcb->kprobe_status = KPROBE_HIT_SSDONE; 240 p->post_handler(p, regs, 0); 241 } 242 } 243 __this_cpu_write(current_kprobe, NULL); 244 out: 245 ftrace_test_recursion_unlock(bit); 246 } 247 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 248 249 int arch_prepare_kprobe_ftrace(struct kprobe *p) 250 { 251 p->ainsn.insn = NULL; 252 return 0; 253 } 254 #endif 255