Yaya48
cf256aa081
Upstream: https://gitlab.com/qemu-project/qemu.git Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475
51 lines
1.3 KiB
C
51 lines
1.3 KiB
C
/*
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* Utility function to get the minimum mmap address.
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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#include "qemu/osdep.h"
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#include "user/mmap-min-addr.h"
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#ifdef __FreeBSD__
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#include <sys/sysctl.h>
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#include <sys/user.h>
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#endif
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uintptr_t mmap_min_addr;
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static void __attribute__((constructor)) init(void)
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{
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#ifdef __linux__
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/*
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* We prefer to not make NULL pointers accessible to QEMU.
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* If something goes wrong below, fall back to 1 page.
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*/
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size_t min_addr = qemu_real_host_page_size();
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/*
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* Read in mmap_min_addr kernel parameter. This value is used
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* When loading the ELF image to determine whether guest_base
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* is needed. It is also used in mmap_find_vma.
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*/
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FILE *fp = fopen("/proc/sys/vm/mmap_min_addr", "r");
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if (fp) {
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unsigned long tmp;
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if (fscanf(fp, "%lu", &tmp) == 1 && tmp != 0) {
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min_addr = MAX(min_addr, tmp);
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}
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fclose(fp);
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}
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mmap_min_addr = min_addr;
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#elif defined(__FreeBSD__)
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int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_VM_LAYOUT, getpid() };
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struct kinfo_vm_layout info;
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size_t info_len = sizeof(info);
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mmap_min_addr =
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(sysctl(mib, ARRAY_SIZE(mib), &info, &info_len, NULL, 0) < 0
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? qemu_real_host_page_size()
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: info.kvm_min_user_addr);
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#else
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# error
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#endif
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}
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