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67 lines
3.3 KiB
C
67 lines
3.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 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/calls/calls.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/asmflag.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/mremap.h"
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#include "libc/sysv/errfuns.h"
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/**
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* Relocates memory.
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*
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* This function lets you move to to different addresses witohut copying
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* it. This system call is currently supported on Linux and NetBSD. Your
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* C library runtime won't have any awareness of this memory, so certain
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* features like ASAN memory safety and kprintf() won't work as well.
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*/
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privileged void *sys_mremap(void *p, size_t n, size_t m, int f, void *q) {
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bool cf;
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uintptr_t rax, rdi, rsi, rdx;
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register uintptr_t r8 asm("r8");
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register uintptr_t r10 asm("r10");
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if (IsLinux()) {
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r10 = f;
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r8 = (uintptr_t)q;
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asm("syscall"
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: "=a"(rax)
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: "0"(0x019), "D"(p), "S"(n), "d"(m), "r"(r10), "r"(r8)
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: "rcx", "r11", "memory", "cc");
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if (rax > -4096ul) errno = -rax, rax = -1;
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} else if (IsNetbsd()) {
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if (f & MREMAP_MAYMOVE) {
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rax = 0x19B;
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r10 = m;
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r8 = (f & MREMAP_FIXED) ? MAP_FIXED : 0;
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asm(CFLAG_ASM("syscall")
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: CFLAG_CONSTRAINT(cf), "+a"(rax), "=d"(rdx)
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: "D"(p), "S"(n), "2"(q), "r"(r10), "r"(r8)
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: "rcx", "r9", "r11", "memory", "cc");
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if (cf) errno = rax, rax = -1;
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} else {
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rax = einval();
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}
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} else {
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rax = enosys();
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}
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KERNTRACE("sys_mremap(%p, %'zu, %'zu, %#b, %p) → %p% m", p, n, m, f, q, rax);
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return (void *)rax;
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}
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