arch/parisc/kernel/ftrace.c

   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(&current->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
  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 ftrace_regs *fregs)
 208 {
 209         struct kprobe_ctlblk *kcb;
 210         struct pt_regs *regs;
 211         struct kprobe *p;
 212         int bit;
 213
 214         bit = ftrace_test_recursion_trylock(ip, parent_ip);
 215         if (bit < 0)
 216                 return;
 217
 218         regs = ftrace_get_regs(fregs);
 219         preempt_disable_notrace();
 220         p = get_kprobe((kprobe_opcode_t *)ip);
 221         if (unlikely(!p) || kprobe_disabled(p))
 222                 goto out;
 223
 224         if (kprobe_running()) {
 225                 kprobes_inc_nmissed_count(p);
 226                 goto out;
 227         }
 228
 229         __this_cpu_write(current_kprobe, p);
 230
 231         kcb = get_kprobe_ctlblk();
 232         kcb->kprobe_status = KPROBE_HIT_ACTIVE;
 233
 234         regs->iaoq[0] = ip;
 235         regs->iaoq[1] = ip + 4;
 236
 237         if (!p->pre_handler || !p->pre_handler(p, regs)) {
 238                 regs->iaoq[0] = ip + 4;
 239                 regs->iaoq[1] = ip + 8;
 240
 241                 if (unlikely(p->post_handler)) {
 242                         kcb->kprobe_status = KPROBE_HIT_SSDONE;
 243                         p->post_handler(p, regs, 0);
 244                 }
 245         }
 246         __this_cpu_write(current_kprobe, NULL);
 247 out:
 248         preempt_enable_notrace();
 249         ftrace_test_recursion_unlock(bit);
 250 }
 251 NOKPROBE_SYMBOL(kprobe_ftrace_handler);
 252
 253 int arch_prepare_kprobe_ftrace(struct kprobe *p)
 254 {
 255         p->ainsn.insn = NULL;
 256         return 0;
 257 }
 258 #endif