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93 lines
2.1 KiB
93 lines
2.1 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* arch/sh/kernel/vsyscall/vsyscall.c |
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* |
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* Copyright (C) 2006 Paul Mundt |
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* |
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* vDSO randomization |
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* Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar |
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*/ |
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#include <linux/mm.h> |
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#include <linux/kernel.h> |
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#include <linux/init.h> |
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#include <linux/gfp.h> |
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#include <linux/module.h> |
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#include <linux/elf.h> |
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#include <linux/sched.h> |
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#include <linux/err.h> |
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/* |
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* Should the kernel map a VDSO page into processes and pass its |
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* address down to glibc upon exec()? |
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*/ |
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unsigned int __read_mostly vdso_enabled = 1; |
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EXPORT_SYMBOL_GPL(vdso_enabled); |
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static int __init vdso_setup(char *s) |
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{ |
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vdso_enabled = simple_strtoul(s, NULL, 0); |
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return 1; |
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} |
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__setup("vdso=", vdso_setup); |
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/* |
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* These symbols are defined by vsyscall.o to mark the bounds |
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* of the ELF DSO images included therein. |
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*/ |
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extern const char vsyscall_trapa_start, vsyscall_trapa_end; |
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static struct page *syscall_pages[1]; |
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int __init vsyscall_init(void) |
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{ |
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void *syscall_page = (void *)get_zeroed_page(GFP_ATOMIC); |
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syscall_pages[0] = virt_to_page(syscall_page); |
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/* |
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* XXX: Map this page to a fixmap entry if we get around |
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* to adding the page to ELF core dumps |
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*/ |
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memcpy(syscall_page, |
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&vsyscall_trapa_start, |
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&vsyscall_trapa_end - &vsyscall_trapa_start); |
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return 0; |
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} |
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/* Setup a VMA at program startup for the vsyscall page */ |
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) |
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{ |
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struct mm_struct *mm = current->mm; |
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unsigned long addr; |
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int ret; |
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if (mmap_write_lock_killable(mm)) |
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return -EINTR; |
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addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); |
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if (IS_ERR_VALUE(addr)) { |
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ret = addr; |
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goto up_fail; |
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} |
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ret = install_special_mapping(mm, addr, PAGE_SIZE, |
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VM_READ | VM_EXEC | |
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VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC, |
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syscall_pages); |
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if (unlikely(ret)) |
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goto up_fail; |
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current->mm->context.vdso = (void *)addr; |
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up_fail: |
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mmap_write_unlock(mm); |
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return ret; |
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} |
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const char *arch_vma_name(struct vm_area_struct *vma) |
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{ |
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if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) |
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return "[vdso]"; |
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return NULL; |
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}
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