102 lines
2.5 KiB
C
Executable file
102 lines
2.5 KiB
C
Executable file
/*
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* vDSO implementation for Hexagon
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*
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* Copyright (c) 2011, The Linux Foundation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include <linux/err.h>
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#include <linux/mm.h>
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#include <linux/vmalloc.h>
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#include <linux/binfmts.h>
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#include <asm/vdso.h>
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static struct page *vdso_page;
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/* Create a vDSO page holding the signal trampoline.
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* We want this for a non-executable stack.
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*/
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static int __init vdso_init(void)
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{
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struct hexagon_vdso *vdso;
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vdso_page = alloc_page(GFP_KERNEL);
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if (!vdso_page)
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panic("Cannot allocate vdso");
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vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
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if (!vdso)
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panic("Cannot map vdso");
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clear_page(vdso);
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/* Install the signal trampoline; currently looks like this:
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* r6 = #__NR_rt_sigreturn;
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* trap0(#1);
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*/
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vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
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vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];
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vunmap(vdso);
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return 0;
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}
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arch_initcall(vdso_init);
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/*
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* Called from binfmt_elf. Create a VMA for the vDSO page.
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*/
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int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
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{
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int ret;
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unsigned long vdso_base;
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struct mm_struct *mm = current->mm;
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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/* Try to get it loaded right near ld.so/glibc. */
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vdso_base = STACK_TOP;
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vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
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if (IS_ERR_VALUE(vdso_base)) {
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ret = vdso_base;
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goto up_fail;
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}
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/* MAYWRITE to allow gdb to COW and set breakpoints. */
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ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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&vdso_page);
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if (ret)
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goto up_fail;
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mm->context.vdso = (void *)vdso_base;
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up_fail:
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up_write(&mm->mmap_sem);
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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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