arch/um/kernel/skas/stub.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2021 Benjamin Berg <[email protected]>
   4  */
   5
   6 #include <sysdep/stub.h>
   7
   8 static __always_inline int syscall_handler(struct stub_data *d)
   9 {
  10         int i;
  11         unsigned long res;
  12
  13         for (i = 0; i < d->syscall_data_len; i++) {
  14                 struct stub_syscall *sc = &d->syscall_data[i];
  15
  16                 switch (sc->syscall) {
  17                 case STUB_SYSCALL_MMAP:
  18                         res = stub_syscall6(STUB_MMAP_NR,
  19                                             sc->mem.addr, sc->mem.length,
  20                                             sc->mem.prot,
  21                                             MAP_SHARED | MAP_FIXED,
  22                                             sc->mem.fd, sc->mem.offset);
  23                         if (res != sc->mem.addr) {
  24                                 d->err = res;
  25                                 d->syscall_data_len = i;
  26                                 return -1;
  27                         }
  28                         break;
  29                 case STUB_SYSCALL_MUNMAP:
  30                         res = stub_syscall2(__NR_munmap,
  31                                             sc->mem.addr, sc->mem.length);
  32                         if (res) {
  33                                 d->err = res;
  34                                 d->syscall_data_len = i;
  35                                 return -1;
  36                         }
  37                         break;
  38                 default:
  39                         d->err = -95; /* EOPNOTSUPP */
  40                         d->syscall_data_len = i;
  41                         return -1;
  42                 }
  43         }
  44
  45         d->err = 0;
  46         d->syscall_data_len = 0;
  47
  48         return 0;
  49 }
  50
  51 void __section(".__syscall_stub")
  52 stub_syscall_handler(void)
  53 {
  54         struct stub_data *d = get_stub_data();
  55
  56         syscall_handler(d);
  57
  58         trap_myself();
  59 }