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 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 #ifdef 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 97 int __init ftrace_dyn_arch_init(void) 98 { 99 return 0; 100 } 101 102 int ftrace_update_ftrace_func(ftrace_func_t func) 103 { 104 ftrace_func = func; 105 return 0; 106 } 107 108 int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, 109 unsigned long addr) 110 { 111 return 0; 112 } 113 114 unsigned long ftrace_call_adjust(unsigned long addr) 115 { 116 return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4; 117 } 118 119 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) 120 { 121 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 122 u32 *tramp; 123 int size, ret, i; 124 void *ip; 125 126 #ifdef CONFIG_64BIT 127 unsigned long addr2 = 128 (unsigned long)dereference_function_descriptor((void *)addr); 129 130 u32 ftrace_trampoline[] = { 131 0x73c10208, /* std,ma r1,100(sp) */ 132 0x0c2110c1, /* ldd -10(r1),r1 */ 133 0xe820d002, /* bve,n (r1) */ 134 addr2 >> 32, 135 addr2 & 0xffffffff, 136 0xe83f1fd7, /* b,l,n .-14,r1 */ 137 }; 138 139 u32 ftrace_trampoline_unaligned[] = { 140 addr2 >> 32, 141 addr2 & 0xffffffff, 142 0x37de0200, /* ldo 100(sp),sp */ 143 0x73c13e01, /* std r1,-100(sp) */ 144 0x34213ff9, /* ldo -4(r1),r1 */ 145 0x50213fc1, /* ldd -20(r1),r1 */ 146 0xe820d002, /* bve,n (r1) */ 147 0xe83f1fcf, /* b,l,n .-20,r1 */ 148 }; 149 150 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) > 151 FTRACE_PATCHABLE_FUNCTION_SIZE); 152 #else 153 u32 ftrace_trampoline[] = { 154 (u32)addr, 155 0x6fc10080, /* stw,ma r1,40(sp) */ 156 0x48213fd1, /* ldw -18(r1),r1 */ 157 0xe820c002, /* bv,n r0(r1) */ 158 0xe83f1fdf, /* b,l,n .-c,r1 */ 159 }; 160 #endif 161 162 BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) > 163 FTRACE_PATCHABLE_FUNCTION_SIZE); 164 165 size = sizeof(ftrace_trampoline); 166 tramp = ftrace_trampoline; 167 168 #ifdef CONFIG_64BIT 169 if (rec->ip & 0x4) { 170 size = sizeof(ftrace_trampoline_unaligned); 171 tramp = ftrace_trampoline_unaligned; 172 } 173 #endif 174 175 ip = (void *)(rec->ip + 4 - size); 176 177 ret = copy_from_kernel_nofault(insn, ip, size); 178 if (ret) 179 return ret; 180 181 for (i = 0; i < size / 4; i++) { 182 if (insn[i] != INSN_NOP) 183 return -EINVAL; 184 } 185 186 __patch_text_multiple(ip, tramp, size); 187 return 0; 188 } 189 190 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, 191 unsigned long addr) 192 { 193 u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE]; 194 int i; 195 196 for (i = 0; i < ARRAY_SIZE(insn); i++) 197 insn[i] = INSN_NOP; 198 199 __patch_text((void *)rec->ip, INSN_NOP); 200 __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn), 201 insn, sizeof(insn)-4); 202 return 0; 203 } 204 #endif 205 206 #ifdef CONFIG_KPROBES_ON_FTRACE 207 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 208 struct ftrace_ops *ops, struct ftrace_regs *fregs) 209 { 210 struct kprobe_ctlblk *kcb; 211 struct pt_regs *regs; 212 struct kprobe *p; 213 int bit; 214 215 bit = ftrace_test_recursion_trylock(ip, parent_ip); 216 if (bit < 0) 217 return; 218 219 regs = ftrace_get_regs(fregs); 220 preempt_disable_notrace(); 221 p = get_kprobe((kprobe_opcode_t *)ip); 222 if (unlikely(!p) || kprobe_disabled(p)) 223 goto out; 224 225 if (kprobe_running()) { 226 kprobes_inc_nmissed_count(p); 227 goto out; 228 } 229 230 __this_cpu_write(current_kprobe, p); 231 232 kcb = get_kprobe_ctlblk(); 233 kcb->kprobe_status = KPROBE_HIT_ACTIVE; 234 235 regs->iaoq[0] = ip; 236 regs->iaoq[1] = ip + 4; 237 238 if (!p->pre_handler || !p->pre_handler(p, regs)) { 239 regs->iaoq[0] = ip + 4; 240 regs->iaoq[1] = ip + 8; 241 242 if (unlikely(p->post_handler)) { 243 kcb->kprobe_status = KPROBE_HIT_SSDONE; 244 p->post_handler(p, regs, 0); 245 } 246 } 247 __this_cpu_write(current_kprobe, NULL); 248 out: 249 preempt_enable_notrace(); 250 ftrace_test_recursion_unlock(bit); 251 } 252 NOKPROBE_SYMBOL(kprobe_ftrace_handler); 253 254 int arch_prepare_kprobe_ftrace(struct kprobe *p) 255 { 256 p->ainsn.insn = NULL; 257 return 0; 258 } 259 #endif 260