projects / thirdparty / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| 581c785b | 1 | /* Copyright (C) 2001-2022 Free Software Foundation, Inc. |
| c9cf6dde AJ |
2 | This file is part of the GNU C Library. |
| 3 | ||
| 4 | The GNU C Library is free software; you can redistribute it and/or | |
| 5 | modify it under the terms of the GNU Lesser General Public | |
| 6 | License as published by the Free Software Foundation; either | |
| 7 | version 2.1 of the License, or (at your option) any later version. | |
| 8 | ||
| 9 | The GNU C Library is distributed in the hope that it will be useful, | |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 12 | Lesser General Public License for more details. | |
| 13 | ||
| 14 | You should have received a copy of the GNU Lesser General Public | |
| 59ba27a6 | 15 | License along with the GNU C Library; if not, see |
| 5a82c748 | 16 | <https://www.gnu.org/licenses/>. */ |
| c9cf6dde AJ |
17 | |
| 18 | #include <sysdep.h> | |
| 19 | #define _ERRNO_H 1 | |
| 20 | #include <bits/errno.h> | |
| e2787137 RM |
21 | #include <tcb-offsets.h> |
| 22 | ||
| c9cf6dde AJ |
23 | /* Clone the calling process, but without copying the whole address space. |
| 24 | The calling process is suspended until the new process exits or is | |
| 25 | replaced by a call to `execve'. Return -1 for errors, 0 to the new process, | |
| 26 | and the process ID of the new process to the old process. */ | |
| 27 | ||
| 28 | ENTRY (__vfork) | |
| 29 | ||
| 04d12383 AJ |
30 | /* Pop the return PC value into RDI. We need a register that |
| 31 | is preserved by the syscall and that we're allowed to destroy. */ | |
| acd42b78 | 32 | popq %rdi |
| 0e328c85 | 33 | cfi_adjust_cfa_offset(-8) |
| 6c30d38f | 34 | cfi_register(%rip, %rdi) |
| c9cf6dde AJ |
35 | |
| 36 | /* Stuff the syscall number in RAX and enter into the kernel. */ | |
| 37 | movl $SYS_ify (vfork), %eax | |
| 38 | syscall | |
| c9cf6dde | 39 | |
| c9cf6dde | 40 | /* Push back the return PC. */ |
| 04d12383 | 41 | pushq %rdi |
| 0e328c85 | 42 | cfi_adjust_cfa_offset(8) |
| c9cf6dde | 43 | |
| acd42b78 UD |
44 | cmpl $-4095, %eax |
| 45 | jae SYSCALL_ERROR_LABEL /* Branch forward if it failed. */ | |
| 46 | ||
| 3650e1d9 | 47 | #if SHSTK_ENABLED |
| 3650e1d9 L |
48 | /* Check if shadow stack is in use. */ |
| 49 | xorl %esi, %esi | |
| 50 | rdsspq %rsi | |
| 51 | testq %rsi, %rsi | |
| 52 | /* Normal return if shadow stack isn't in use. */ | |
| 53 | je L(no_shstk) | |
| 54 | ||
| c02695d7 L |
55 | testl %eax, %eax |
| 56 | /* In parent, normal return. */ | |
| 57 | jnz L(no_shstk) | |
| 58 | ||
| 59 | /* NB: In child, jump back to caller via indirect branch without | |
| 60 | popping shadow stack which is shared with parent. Keep shadow | |
| 61 | stack mismatched so that child returns in the vfork-calling | |
| 62 | function will trigger SIGSEGV. */ | |
| 63 | popq %rdi | |
| 64 | cfi_adjust_cfa_offset(-8) | |
| 3650e1d9 L |
65 | jmp *%rdi |
| 66 | ||
| 67 | L(no_shstk): | |
| 3650e1d9 L |
68 | #endif |
| 69 | ||
| acd42b78 | 70 | /* Normal return. */ |
| c9cf6dde AJ |
71 | ret |
| 72 | ||
| 73 | PSEUDO_END (__vfork) | |
| a4baf360 | 74 | libc_hidden_def (__vfork) |
| c9cf6dde AJ |
75 | |
| 76 | weak_alias (__vfork, vfork) | |
| e2787137 | 77 | strong_alias (__vfork, __libc_vfork) |