linux/arch/parisc/kernel/ftrace.c
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   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 */
  31static 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
  51void 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
  85int ftrace_enable_ftrace_graph_caller(void)
  86{
  87        return 0;
  88}
  89
  90int ftrace_disable_ftrace_graph_caller(void)
  91{
  92        return 0;
  93}
  94#endif
  95
  96#ifdef CONFIG_DYNAMIC_FTRACE
  97
  98int __init ftrace_dyn_arch_init(void)
  99{
 100        return 0;
 101}
 102int ftrace_update_ftrace_func(ftrace_func_t func)
 103{
 104        return 0;
 105}
 106
 107int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 108                        unsigned long addr)
 109{
 110        return 0;
 111}
 112
 113unsigned long ftrace_call_adjust(unsigned long addr)
 114{
 115        return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
 116}
 117
 118int 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
 189int 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
 206void 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);
 247out:
 248        preempt_enable_notrace();
 249        ftrace_test_recursion_unlock(bit);
 250}
 251NOKPROBE_SYMBOL(kprobe_ftrace_handler);
 252
 253int arch_prepare_kprobe_ftrace(struct kprobe *p)
 254{
 255        p->ainsn.insn = NULL;
 256        return 0;
 257}
 258#endif
 259