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https://github.com/jart/cosmopolitan.git
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197aa0d465
This change introduces support for Linux-style uc_context manipulation that's fast and works well on all supported OSes and architectures. It also integrates with the Cosmpolitan runtime which can show backtraces comprised of multiple stacks and fibers. See the test and example code for further details. This will be used by Mold once it's been vendored
61 lines
2.5 KiB
ArmAsm
61 lines
2.5 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 2022 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/macros.internal.h"
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// Saves machine to 𝑥 and activates 𝑦, i.e.
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//
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// getcontext(x);
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// setcontext(y);
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//
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// Except using this API is safer and goes 2x faster:
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//
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// swapcontext(x, y);
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//
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// @return 0 on success, or -1 w/ errno
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// @returnstwice
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// @threadsafe
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.ftrace1
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swapcontext:
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.ftrace2
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#include "libc/calls/getcontext.inc"
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#ifdef __x86_64__
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push %rbp
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mov %rsp,%rbp
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push %rsi
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push %rsi
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call __swapcontextsig
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pop %rdi
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pop %rdi
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pop %rbp
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test %eax,%eax
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jnz 1f
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#elif defined(__aarch64__)
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stp x29,x30,[sp,#-32]!
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mov x29,sp
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str x1,[sp,16]
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bl __swapcontextsig
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ldr x1,[sp,16]
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ldp x29,x30,[sp],#32
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cbnz w0,1f
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mov x0,x1
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#endif
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jmp __tailcontext
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1: ret
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.endfn swapcontext,globl
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