cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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vdso.c (1926B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * vDSO implementation for Hexagon
      4 *
      5 * Copyright (c) 2011, The Linux Foundation. All rights reserved.
      6 */
      7
      8#include <linux/err.h>
      9#include <linux/mm.h>
     10#include <linux/vmalloc.h>
     11#include <linux/binfmts.h>
     12
     13#include <asm/vdso.h>
     14
     15static struct page *vdso_page;
     16
     17/* Create a vDSO page holding the signal trampoline.
     18 * We want this for a non-executable stack.
     19 */
     20static int __init vdso_init(void)
     21{
     22	struct hexagon_vdso *vdso;
     23
     24	vdso_page = alloc_page(GFP_KERNEL);
     25	if (!vdso_page)
     26		panic("Cannot allocate vdso");
     27
     28	vdso = vmap(&vdso_page, 1, 0, PAGE_KERNEL);
     29	if (!vdso)
     30		panic("Cannot map vdso");
     31	clear_page(vdso);
     32
     33	/* Install the signal trampoline; currently looks like this:
     34	 *	r6 = #__NR_rt_sigreturn;
     35	 *	trap0(#1);
     36	 */
     37	vdso->rt_signal_trampoline[0] = __rt_sigtramp_template[0];
     38	vdso->rt_signal_trampoline[1] = __rt_sigtramp_template[1];
     39
     40	vunmap(vdso);
     41
     42	return 0;
     43}
     44arch_initcall(vdso_init);
     45
     46/*
     47 * Called from binfmt_elf.  Create a VMA for the vDSO page.
     48 */
     49int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
     50{
     51	int ret;
     52	unsigned long vdso_base;
     53	struct mm_struct *mm = current->mm;
     54
     55	if (mmap_write_lock_killable(mm))
     56		return -EINTR;
     57
     58	/* Try to get it loaded right near ld.so/glibc. */
     59	vdso_base = STACK_TOP;
     60
     61	vdso_base = get_unmapped_area(NULL, vdso_base, PAGE_SIZE, 0, 0);
     62	if (IS_ERR_VALUE(vdso_base)) {
     63		ret = vdso_base;
     64		goto up_fail;
     65	}
     66
     67	/* MAYWRITE to allow gdb to COW and set breakpoints. */
     68	ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
     69				      VM_READ|VM_EXEC|
     70				      VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
     71				      &vdso_page);
     72
     73	if (ret)
     74		goto up_fail;
     75
     76	mm->context.vdso = (void *)vdso_base;
     77
     78up_fail:
     79	mmap_write_unlock(mm);
     80	return ret;
     81}
     82
     83const char *arch_vma_name(struct vm_area_struct *vma)
     84{
     85	if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
     86		return "[vdso]";
     87	return NULL;
     88}