From 9e37a2e8546f9e48ea76c839116fa5174d14e033 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Wed, 6 Apr 2022 08:44:49 +0200 Subject: [PATCH] s390/vdso: map vdso above stack In the current code vdso is mapped below the stack. This is problematic when programs mapped to the top of the address space are allocating a lot of memory, because the heap will clash with the vdso. To avoid this map the vdso above the stack and move STACK_TOP so that it all fits into three level paging. Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens --- arch/s390/include/asm/processor.h | 7 ++++--- arch/s390/kernel/vdso.c | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index a3ab8cbcc5e4..add764a2be8c 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -95,9 +95,10 @@ unsigned long vdso_size(void); (_REGION3_SIZE >> 1) : (_REGION2_SIZE >> 1)) #define TASK_SIZE_MAX (-PAGE_SIZE) -#define STACK_TOP (test_thread_flag(TIF_31BIT) ? \ - _REGION3_SIZE : _REGION2_SIZE) -#define STACK_TOP_MAX _REGION2_SIZE +#define VDSO_BASE (STACK_TOP + PAGE_SIZE) +#define VDSO_LIMIT (test_thread_flag(TIF_31BIT) ? _REGION3_SIZE : _REGION2_SIZE) +#define STACK_TOP (VDSO_LIMIT - vdso_size() - PAGE_SIZE) +#define STACK_TOP_MAX (_REGION2_SIZE - vdso_size() - PAGE_SIZE) #define HAVE_ARCH_PICK_MMAP_LAYOUT diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index 22cb727d5821..7ba84a88ea2a 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -221,7 +221,7 @@ unsigned long vdso_size(void) int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) { - return map_vdso(0, vdso_size()); + return map_vdso(VDSO_BASE, vdso_size()); } static struct page ** __init vdso_setup_pages(void *start, void *end)