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arm64: vdso: move data page before code pages

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Andy pointed out that binutils generates additional sections in the vdso
image (e.g. section string table) which, if our .text section gets big
enough, could cross a page boundary and end up screwing up the location
where the kernel expects to put the data page.

This patch solves the issue in the same manner as x86_32, by moving the
data page before the code pages.

Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2014-07-09 19:22:13 +01:00 committed by Catalin Marinas
parent 2fea7f6c98
commit 601255ae3c
2 changed files with 18 additions and 20 deletions
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34
arch/arm64/kernel/vdso.c
View File

@ -121,8 +121,8 @@ static int __init vdso_init(void)
}
vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
pr_info("vdso: %ld pages (%ld code, %ld data) at base %p\n",
vdso_pages + 1, vdso_pages, 1L, &vdso_start);
pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
/* Allocate the vDSO pagelist, plus a page for the data. */
vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
@ -130,22 +130,22 @@ static int __init vdso_init(void)
if (vdso_pagelist == NULL)
return -ENOMEM;
/* Grab the vDSO data page. */
vdso_pagelist[0] = virt_to_page(vdso_data);
/* Grab the vDSO code pages. */
for (i = 0; i < vdso_pages; i++)
vdso_pagelist[i] = virt_to_page(&vdso_start + i * PAGE_SIZE);
/* Grab the vDSO data page. */
vdso_pagelist[i] = virt_to_page(vdso_data);
vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE);
/* Populate the special mapping structures */
vdso_spec[0] = (struct vm_special_mapping) {
.name = "[vdso]",
.name = "[vvar]",
.pages = vdso_pagelist,
};
vdso_spec[1] = (struct vm_special_mapping) {
.name = "[vvar]",
.pages = vdso_pagelist + vdso_pages,
.name = "[vdso]",
.pages = &vdso_pagelist[1],
};
return 0;
@ -169,22 +169,22 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
ret = ERR_PTR(vdso_base);
goto up_fail;
}
mm->context.vdso = (void *)vdso_base;
ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_MAYREAD,
&vdso_spec[0]);
if (IS_ERR(ret))
goto up_fail;
vdso_base += vdso_text_len;
ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
VM_READ|VM_MAYREAD,
vdso_base += PAGE_SIZE;
mm->context.vdso = (void *)vdso_base;
ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
&vdso_spec[1]);
if (IS_ERR(ret))
goto up_fail;
up_write(&mm->mmap_sem);
return 0;

4
arch/arm64/kernel/vdso/vdso.lds.S
View File

@ -28,6 +28,7 @@ OUTPUT_ARCH(aarch64)
SECTIONS
{
PROVIDE(_vdso_data = . - PAGE_SIZE);
. = VDSO_LBASE + SIZEOF_HEADERS;
.hash : { *(.hash) } :text
@ -57,9 +58,6 @@ SECTIONS
_end = .;
PROVIDE(end = .);
. = ALIGN(PAGE_SIZE);
PROVIDE(_vdso_data = .);
/DISCARD/ : {
*(.note.GNU-stack)
*(.data .data.* .gnu.linkonce.d.* .sdata*)