From 67dece7d4c5841e84a3c795e79bf0dcd5be54f55 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Thu, 27 Oct 2016 17:15:16 +0300 Subject: [PATCH] x86/vdso: Set vDSO pointer only after success Those pointers were initialized before call to _install_special_mapping() after the commit: f7b6eb3fa072 ("x86: Set context.vdso before installing the mapping") This is not required anymore as special mappings have their vma name and don't use arch_vma_name() after commit: a62c34bd2a8a ("x86, mm: Improve _install_special_mapping and fix x86 vdso naming") So, this way to init looks less entangled. I even belive that we can remove NULL initializers: - on failure load_elf_binary() will not start a new thread; - arch_prctl will have the same pointers as before syscall. Signed-off-by: Dmitry Safonov Acked-by: Andy Lutomirski Cc: 0x7f454c46@gmail.com Cc: Borislav Petkov Cc: Brian Gerst Cc: Cyrill Gorcunov Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Cc: oleg@redhat.com Link: http://lkml.kernel.org/r/20161027141516.28447-3-dsafonov@virtuozzo.com Signed-off-by: Ingo Molnar --- arch/x86/entry/vdso/vma.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 23c881caabd1..e739002427ed 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -161,8 +161,6 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr) } text_start = addr - image->sym_vvar_start; - current->mm->context.vdso = (void __user *)text_start; - current->mm->context.vdso_image = image; /* * MAYWRITE to allow gdb to COW and set breakpoints @@ -189,14 +187,12 @@ static int map_vdso(const struct vdso_image *image, unsigned long addr) if (IS_ERR(vma)) { ret = PTR_ERR(vma); do_munmap(mm, text_start, image->size); + } else { + current->mm->context.vdso = (void __user *)text_start; + current->mm->context.vdso_image = image; } up_fail: - if (ret) { - current->mm->context.vdso = NULL; - current->mm->context.vdso_image = NULL; - } - up_write(&mm->mmap_sem); return ret; } -- 2.30.2