arm uses a top-down layout by default that fits the generic functions. At the same time, this commit allows to fix the following problems: - one uncovered and not fixed for arm here: https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1429066.html - the use of TASK_SIZE instead of STACK_TOP in mmap_base which, when address space of a task is 26 bits, would assign mmap base way too high. Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx> --- arch/arm/include/asm/processor.h | 2 +- arch/arm/mm/mmap.c | 52 -------------------------------- 2 files changed, 1 insertion(+), 53 deletions(-) diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h index 57fe73ea0f72..03837d325a2f 100644 --- a/arch/arm/include/asm/processor.h +++ b/arch/arm/include/asm/processor.h @@ -143,7 +143,7 @@ static inline void prefetchw(const void *ptr) #endif #endif -#define HAVE_ARCH_PICK_MMAP_LAYOUT +#define ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT #endif diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c index f866870db749..b8d912ac9e61 100644 --- a/arch/arm/mm/mmap.c +++ b/arch/arm/mm/mmap.c @@ -17,33 +17,6 @@ ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \ (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) -/* gap between mmap and stack */ -#define MIN_GAP (128*1024*1024UL) -#define MAX_GAP ((TASK_SIZE)/6*5) - -static int mmap_is_legacy(struct rlimit *rlim_stack) -{ - if (current->personality & ADDR_COMPAT_LAYOUT) - return 1; - - if (rlim_stack->rlim_cur == RLIM_INFINITY) - return 1; - - return sysctl_legacy_va_layout; -} - -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) -{ - unsigned long gap = rlim_stack->rlim_cur; - - if (gap < MIN_GAP) - gap = MIN_GAP; - else if (gap > MAX_GAP) - gap = MAX_GAP; - - return PAGE_ALIGN(TASK_SIZE - gap - rnd); -} - /* * We need to ensure that shared mappings are correctly aligned to * avoid aliasing issues with VIPT caches. We need to ensure that @@ -171,31 +144,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, return addr; } -unsigned long arch_mmap_rnd(void) -{ - unsigned long rnd; - - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); - - return rnd << PAGE_SHIFT; -} - -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) -{ - unsigned long random_factor = 0UL; - - if (current->flags & PF_RANDOMIZE) - random_factor = arch_mmap_rnd(); - - if (mmap_is_legacy(rlim_stack)) { - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; - mm->get_unmapped_area = arch_get_unmapped_area; - } else { - mm->mmap_base = mmap_base(random_factor, rlim_stack); - mm->get_unmapped_area = arch_get_unmapped_area_topdown; - } -} - /* * You really shouldn't be using read() or write() on /dev/mem. This * might go away in the future. -- 2.20.1
