![James Hogan](/assets/img/avatar_default.png)
The page structures associated with the vDSO pages in the kernel image
are calculated using virt_to_page(), which uses __pa() under the hood to
find the pfn associated with the virtual address. The vDSO data pointers
however point to kernel symbols, so __pa_symbol() should really be used
instead.
Since there is no equivalent to virt_to_page() which uses __pa_symbol(),
fix init_vdso_image() to work directly with pfns, calculated with
__phys_to_pfn(__pa_symbol(...)).
This issue broke the Malta Enhanced Virtual Addressing (EVA)
configuration which has a non-default implementation of __pa_symbol().
This is because it uses a physical alias so that the kernel executes
from KSeg0 (VA 0x80000000 -> PA 0x00000000), while RAM is provided to
the kernel in the KUSeg range (VA 0x00000000 -> PA 0x80000000) which
uses the same underlying RAM.
Since there are no page structures associated with the low physical
address region, some arbitrary kernel memory would be interpreted as a
page structure for the vDSO pages and badness ensues.
Fixes: ebb5e78cc6
("MIPS: Initial implementation of a VDSO")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.4.x-
Patchwork: https://patchwork.linux-mips.org/patch/14229/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
187 lines
4.7 KiB
C
187 lines
4.7 KiB
C
/*
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* Copyright (C) 2015 Imagination Technologies
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* Author: Alex Smith <alex.smith@imgtec.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/binfmts.h>
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#include <linux/elf.h>
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/ioport.h>
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#include <linux/irqchip/mips-gic.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/timekeeper_internal.h>
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#include <asm/abi.h>
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#include <asm/vdso.h>
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/* Kernel-provided data used by the VDSO. */
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static union mips_vdso_data vdso_data __page_aligned_data;
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/*
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* Mapping for the VDSO data/GIC pages. The real pages are mapped manually, as
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* what we map and where within the area they are mapped is determined at
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* runtime.
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*/
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static struct page *no_pages[] = { NULL };
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static struct vm_special_mapping vdso_vvar_mapping = {
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.name = "[vvar]",
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.pages = no_pages,
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};
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static void __init init_vdso_image(struct mips_vdso_image *image)
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{
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unsigned long num_pages, i;
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unsigned long data_pfn;
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BUG_ON(!PAGE_ALIGNED(image->data));
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BUG_ON(!PAGE_ALIGNED(image->size));
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num_pages = image->size / PAGE_SIZE;
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data_pfn = __phys_to_pfn(__pa_symbol(image->data));
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for (i = 0; i < num_pages; i++)
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image->mapping.pages[i] = pfn_to_page(data_pfn + i);
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}
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static int __init init_vdso(void)
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{
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init_vdso_image(&vdso_image);
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#ifdef CONFIG_MIPS32_O32
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init_vdso_image(&vdso_image_o32);
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#endif
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#ifdef CONFIG_MIPS32_N32
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init_vdso_image(&vdso_image_n32);
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#endif
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return 0;
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}
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subsys_initcall(init_vdso);
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void update_vsyscall(struct timekeeper *tk)
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{
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vdso_data_write_begin(&vdso_data);
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vdso_data.xtime_sec = tk->xtime_sec;
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vdso_data.xtime_nsec = tk->tkr_mono.xtime_nsec;
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vdso_data.wall_to_mono_sec = tk->wall_to_monotonic.tv_sec;
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vdso_data.wall_to_mono_nsec = tk->wall_to_monotonic.tv_nsec;
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vdso_data.cs_shift = tk->tkr_mono.shift;
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vdso_data.clock_mode = tk->tkr_mono.clock->archdata.vdso_clock_mode;
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if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
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vdso_data.cs_mult = tk->tkr_mono.mult;
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vdso_data.cs_cycle_last = tk->tkr_mono.cycle_last;
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vdso_data.cs_mask = tk->tkr_mono.mask;
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}
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vdso_data_write_end(&vdso_data);
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}
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void update_vsyscall_tz(void)
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{
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if (vdso_data.clock_mode != VDSO_CLOCK_NONE) {
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vdso_data.tz_minuteswest = sys_tz.tz_minuteswest;
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vdso_data.tz_dsttime = sys_tz.tz_dsttime;
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}
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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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struct mips_vdso_image *image = current->thread.abi->vdso;
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struct mm_struct *mm = current->mm;
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unsigned long gic_size, vvar_size, size, base, data_addr, vdso_addr;
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struct vm_area_struct *vma;
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struct resource gic_res;
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int ret;
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if (down_write_killable(&mm->mmap_sem))
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return -EINTR;
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/* Map delay slot emulation page */
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base = mmap_region(NULL, STACK_TOP, PAGE_SIZE,
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VM_READ|VM_WRITE|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
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0);
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if (IS_ERR_VALUE(base)) {
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ret = base;
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goto out;
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}
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/*
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* Determine total area size. This includes the VDSO data itself, the
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* data page, and the GIC user page if present. Always create a mapping
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* for the GIC user area if the GIC is present regardless of whether it
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* is the current clocksource, in case it comes into use later on. We
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* only map a page even though the total area is 64K, as we only need
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* the counter registers at the start.
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*/
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gic_size = gic_present ? PAGE_SIZE : 0;
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vvar_size = gic_size + PAGE_SIZE;
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size = vvar_size + image->size;
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base = get_unmapped_area(NULL, 0, size, 0, 0);
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if (IS_ERR_VALUE(base)) {
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ret = base;
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goto out;
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}
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data_addr = base + gic_size;
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vdso_addr = data_addr + PAGE_SIZE;
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vma = _install_special_mapping(mm, base, vvar_size,
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VM_READ | VM_MAYREAD,
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&vdso_vvar_mapping);
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if (IS_ERR(vma)) {
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ret = PTR_ERR(vma);
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goto out;
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}
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/* Map GIC user page. */
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if (gic_size) {
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ret = gic_get_usm_range(&gic_res);
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if (ret)
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goto out;
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ret = io_remap_pfn_range(vma, base,
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gic_res.start >> PAGE_SHIFT,
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gic_size,
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pgprot_noncached(PAGE_READONLY));
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if (ret)
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goto out;
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}
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/* Map data page. */
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ret = remap_pfn_range(vma, data_addr,
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virt_to_phys(&vdso_data) >> PAGE_SHIFT,
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PAGE_SIZE, PAGE_READONLY);
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if (ret)
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goto out;
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/* Map VDSO image. */
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vma = _install_special_mapping(mm, vdso_addr, image->size,
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VM_READ | VM_EXEC |
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VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
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&image->mapping);
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if (IS_ERR(vma)) {
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ret = PTR_ERR(vma);
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goto out;
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}
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mm->context.vdso = (void *)vdso_addr;
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ret = 0;
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out:
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up_write(&mm->mmap_sem);
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return ret;
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}
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