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Implement swapcontext() and makecontext()

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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
This commit is contained in:
Justine Tunney 2023-07-02 03:50:29 -07:00
parent 7ec84655b4
commit 197aa0d465
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GPG key ID: BE714B4575D6E328
28 changed files with 617 additions and 355 deletions
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libc/calls/getcontext.inc Normal file
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/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
// @fileoverview textual include for loading processor state
#ifdef __x86_64__
mov %r8,40(%rdi)
mov %r9,48(%rdi)
mov %r10,56(%rdi)
mov %r11,64(%rdi)
mov %r12,72(%rdi)
mov %r13,80(%rdi)
mov %r14,88(%rdi)
mov %r15,96(%rdi)
mov %rdi,104(%rdi)
mov %rsi,112(%rdi)
mov %rbp,120(%rdi)
mov %rbx,128(%rdi)
mov %rdx,136(%rdi)
mov %rcx,152(%rdi)
lea 8(%rsp),%rax
mov %rax,160(%rdi) // rsp = caller's rsp
mov (%rsp),%rax
mov %rax,168(%rdi) // rip = return address
lea 608(%rdi),%rax
movaps %xmm0,-0x80(%rax)
movaps %xmm1,-0x70(%rax)
movaps %xmm2,-0x60(%rax)
movaps %xmm3,-0x50(%rax)
movaps %xmm4,-0x40(%rax)
movaps %xmm5,-0x30(%rax)
movaps %xmm6,-0x20(%rax)
movaps %xmm7,-0x10(%rax)
movaps %xmm8,0x00(%rax)
movaps %xmm9,0x10(%rax)
movaps %xmm10,0x20(%rax)
movaps %xmm11,0x30(%rax)
movaps %xmm12,0x40(%rax)
movaps %xmm13,0x50(%rax)
movaps %xmm14,0x60(%rax)
movaps %xmm15,0x70(%rax)
lea 320(%rdi),%rax // rax = &__fpustate
mov %rax,224(%rdi) // fpregs = rax
#elif defined(__aarch64__)
#define REGS(i) 184+i*8
stp xzr,x1,[x0,REGS(0)] // x0 = 0
stp x2,x3,[x0,REGS(2)]
stp x4,x5,[x0,REGS(4)]
stp x6,x7,[x0,REGS(6)]
stp x8,x9,[x0,REGS(8)]
stp x10,x11,[x0,REGS(10)]
stp x12,x13,[x0,REGS(12)]
stp x14,x15,[x0,REGS(14)]
stp x16,x17,[x0,REGS(16)]
stp x18,x19,[x0,REGS(18)]
stp x20,x21,[x0,REGS(20)]
stp x22,x23,[x0,REGS(22)]
stp x24,x25,[x0,REGS(24)]
stp x26,x27,[x0,REGS(26)]
stp x28,x29,[x0,REGS(28)]
str x30,[x0,REGS(30)]
mov x15,sp
stp x15,x30,[x0,REGS(31)] // sp, pc = caller sp, ret address
str xzr,[x0,448] // pstate = 0
str xzr,[x0,456] // no vectors yet
#else
#error "unsupported architecture"
#endif