arch/riscv/kernel/probes/uprobes.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <linux/highmem.h>
   4 #include <linux/ptrace.h>
   5 #include <linux/uprobes.h>
   6
   7 #include "decode-insn.h"
   8
   9 #define UPROBE_TRAP_NR  UINT_MAX
  10
  11 bool is_swbp_insn(uprobe_opcode_t *insn)
  12 {
  13 #ifdef CONFIG_RISCV_ISA_C
  14         return (*insn & 0xffff) == UPROBE_SWBP_INSN;
  15 #else
  16         return *insn == UPROBE_SWBP_INSN;
  17 #endif
  18 }
  19
  20 unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
  21 {
  22         return instruction_pointer(regs);
  23 }
  24
  25 int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
  26                              unsigned long addr)
  27 {
  28         probe_opcode_t opcode;
  29
  30         opcode = *(probe_opcode_t *)(&auprobe->insn[0]);
  31
  32         auprobe->insn_size = GET_INSN_LENGTH(opcode);
  33
  34         switch (riscv_probe_decode_insn(&opcode, &auprobe->api)) {
  35         case INSN_REJECTED:
  36                 return -EINVAL;
  37
  38         case INSN_GOOD_NO_SLOT:
  39                 auprobe->simulate = true;
  40                 break;
  41
  42         case INSN_GOOD:
  43                 auprobe->simulate = false;
  44                 break;
  45
  46         default:
  47                 return -EINVAL;
  48         }
  49
  50         return 0;
  51 }
  52
  53 int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
  54 {
  55         struct uprobe_task *utask = current->utask;
  56
  57         utask->autask.saved_cause = current->thread.bad_cause;
  58         current->thread.bad_cause = UPROBE_TRAP_NR;
  59
  60         instruction_pointer_set(regs, utask->xol_vaddr);
  61
  62         return 0;
  63 }
  64
  65 int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
  66 {
  67         struct uprobe_task *utask = current->utask;
  68
  69         WARN_ON_ONCE(current->thread.bad_cause != UPROBE_TRAP_NR);
  70
  71         instruction_pointer_set(regs, utask->vaddr + auprobe->insn_size);
  72
  73         return 0;
  74 }
  75
  76 bool arch_uprobe_xol_was_trapped(struct task_struct *t)
  77 {
  78         if (t->thread.bad_cause != UPROBE_TRAP_NR)
  79                 return true;
  80
  81         return false;
  82 }
  83
  84 bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
  85 {
  86         probe_opcode_t insn;
  87         unsigned long addr;
  88
  89         if (!auprobe->simulate)
  90                 return false;
  91
  92         insn = *(probe_opcode_t *)(&auprobe->insn[0]);
  93         addr = instruction_pointer(regs);
  94
  95         if (auprobe->api.handler)
  96                 auprobe->api.handler(insn, addr, regs);
  97
  98         return true;
  99 }
 100
 101 void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
 102 {
 103         struct uprobe_task *utask = current->utask;
 104
 105         /*
 106          * Task has received a fatal signal, so reset back to probbed
 107          * address.
 108          */
 109         instruction_pointer_set(regs, utask->vaddr);
 110 }
 111
 112 bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
 113                 struct pt_regs *regs)
 114 {
 115         if (ctx == RP_CHECK_CHAIN_CALL)
 116                 return regs->sp <= ret->stack;
 117         else
 118                 return regs->sp < ret->stack;
 119 }
 120
 121 unsigned long
 122 arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
 123                                   struct pt_regs *regs)
 124 {
 125         unsigned long ra;
 126
 127         ra = regs->ra;
 128
 129         regs->ra = trampoline_vaddr;
 130
 131         return ra;
 132 }
 133
 134 int arch_uprobe_exception_notify(struct notifier_block *self,
 135                                  unsigned long val, void *data)
 136 {
 137         return NOTIFY_DONE;
 138 }
 139
 140 bool uprobe_breakpoint_handler(struct pt_regs *regs)
 141 {
 142         if (uprobe_pre_sstep_notifier(regs))
 143                 return true;
 144
 145         return false;
 146 }
 147
 148 bool uprobe_single_step_handler(struct pt_regs *regs)
 149 {
 150         if (uprobe_post_sstep_notifier(regs))
 151                 return true;
 152
 153         return false;
 154 }
 155
 156 void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
 157                            void *src, unsigned long len)
 158 {
 159         /* Initialize the slot */
 160         void *kaddr = kmap_atomic(page);
 161         void *dst = kaddr + (vaddr & ~PAGE_MASK);
 162
 163         memcpy(dst, src, len);
 164
 165         /* Add ebreak behind opcode to simulate singlestep */
 166         if (vaddr) {
 167                 dst += GET_INSN_LENGTH(*(probe_opcode_t *)src);
 168                 *(uprobe_opcode_t *)dst = __BUG_INSN_32;
 169         }
 170
 171         kunmap_atomic(kaddr);
 172
 173         /*
 174          * We probably need flush_icache_user_page() but it needs vma.
 175          * This should work on most of architectures by default. If
 176          * architecture needs to do something different it can define
 177          * its own version of the function.
 178          */
 179         flush_dcache_page(page);
 180 }