From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/3] arm64: vdso: put vdso datapage in a separate vma
Date: Wed, 9 Jul 2014 19:22:11 +0100 [thread overview]
Message-ID: <1404930133-30324-2-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1404930133-30324-1-git-send-email-will.deacon@arm.com>
The VDSO datapage doesn't need to be executable (no code there) or
CoW-able (the kernel writes the page, so a private copy is totally
useless).
This patch moves the datapage into its own VMA, identified as "[vvar]"
in /proc/<pid>/maps.
Cc: Andy Lutomirski <luto@amacapital•net>
Signed-off-by: Will Deacon <will.deacon@arm•com>
---
arch/arm64/kernel/vdso.c | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 50384fec56c4..84cafbc3eb54 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -138,11 +138,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
- unsigned long vdso_base, vdso_mapping_len;
+ unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
int ret;
+ vdso_text_len = vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
- vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;
+ vdso_mapping_len = vdso_text_len + PAGE_SIZE;
down_write(&mm->mmap_sem);
vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
@@ -152,35 +153,52 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
}
mm->context.vdso = (void *)vdso_base;
- ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,
+ ret = install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pagelist);
- if (ret) {
- mm->context.vdso = NULL;
+ if (ret)
+ goto up_fail;
+
+ vdso_base += vdso_text_len;
+ ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ VM_READ|VM_MAYREAD,
+ vdso_pagelist + vdso_pages);
+ if (ret)
goto up_fail;
- }
-up_fail:
up_write(&mm->mmap_sem);
+ return 0;
+up_fail:
+ mm->context.vdso = NULL;
+ up_write(&mm->mmap_sem);
return ret;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
+ unsigned long vdso_text;
+
+ if (!vma->vm_mm)
+ return NULL;
+
+ vdso_text = (unsigned long)vma->vm_mm->context.vdso;
+
/*
* We can re-use the vdso pointer in mm_context_t for identifying
* the vectors page for compat applications. The vDSO will always
* sit above TASK_UNMAPPED_BASE and so we don't need to worry about
* it conflicting with the vectors base.
*/
- if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) {
+ if (vma->vm_start == vdso_text) {
#ifdef CONFIG_COMPAT
if (vma->vm_start == AARCH32_VECTORS_BASE)
return "[vectors]";
#endif
return "[vdso]";
+ } else if (vma->vm_start == (vdso_text + (vdso_pages << PAGE_SHIFT))) {
+ return "[vvar]";
}
return NULL;
--
2.0.0
next prev parent reply other threads:[~2014-07-09 18:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 18:22 [PATCH 0/3] Bunch of vdso cleanups following feedback from x86 Will Deacon
2014-07-09 18:22 ` Will Deacon [this message]
2014-07-09 19:44 ` [PATCH 1/3] arm64: vdso: put vdso datapage in a separate vma Nathan Lynch
2014-07-09 19:48 ` Andy Lutomirski
2014-07-09 18:22 ` [PATCH 2/3] arm64: vdso: move to _install_special_mapping and remove arch_vma_name Will Deacon
2014-07-09 18:22 ` [PATCH 3/3] arm64: vdso: move data page before code pages Will Deacon
2014-07-24 18:20 ` [PATCH 0/3] Bunch of vdso cleanups following feedback from x86 Christopher Covington
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