From 8715493852783358ef8656a0054a14bf822509cf Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 9 Jul 2014 19:22:11 +0100 Subject: [PATCH] arm64: vdso: put vdso datapage in a separate vma 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//maps. Cc: Andy Lutomirski Signed-off-by: Will Deacon Signed-off-by: Catalin Marinas --- 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; -- 2.11.0