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fabf7f9f02
ASAN and vfork() don't appear to play well together. Maybe in later versions of GCC it'll be better. But vfork() is flirting with danger after all and that probably doesn't make sense in ASAN mode anyway.
84 lines
3.3 KiB
ArmAsm
84 lines
3.3 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/dce.h"
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#include "libc/macros.internal.h"
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.privileged
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#ifdef __FSANITIZE_ADDRESS__
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vfork: jmp fork # TODO: asan and vfork don't mix?
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.endfn vfork,globl
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#else
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// Forks process without copying page tables.
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//
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// This is the same as fork() except it's optimized for the case
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// where the caller invokes execve() immediately afterwards. You
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// can also call functions like close(), dup2(), etc. You cannot
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// call read() safely but you can call pread(). Call _exit() but
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// don't call exit(). Look for the vforksafe function annotation
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//
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// Do not make the assumption that the parent is suspended until
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// the child terminates since this impl calls fork() on Windows.
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//
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// @return pid of child process or 0 if forked process
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// @returnstwice
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// @vforksafe
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vfork:
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#if SupportsWindows()
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testb IsWindows()
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jnz sys_fork_nt
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#endif
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mov __NR_vfork(%rip),%eax
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pop %rsi # saves return address in a register
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#if SupportsBsd()
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testb IsBsd()
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jnz vfork.bsd
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#endif
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syscall
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push %rsi # note it happens twice in same page
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#if SupportsLinux()
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cmp $-4095,%eax
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jae systemfive_error
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#endif
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0: ezlea __vforked,di
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test %eax,%eax
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jz 1f
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decl (%rdi)
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jns 2f # openbsd doesn't actually share mem
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1: incl (%rdi)
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2: ret
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.endfn vfork,globl
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#if SupportsBsd()
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vfork.bsd:
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syscall
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push %rsi
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jc systemfive_errno
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#if SupportsXnu()
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testb IsXnu()
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jz 0b
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neg %edx # edx is 0 for parent and 1 for child
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not %edx # eax always returned with childs pid
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and %edx,%eax
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#endif /* XNU */
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jmp 0b
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.endfn vfork.bsd
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#endif /* BSD */
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#endif /* __FSANITIZE_ADDRESS__ */
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