From 1f6b83e5e4d3aed46eac1d219322fba9c7341cd8 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Wed, 14 Jan 2015 17:51:17 +0100 Subject: s390: avoid z13 cache aliasing Avoid cache aliasing on z13 by aligning shared objects to multiples of 512K. The virtual addresses of a page from a shared file needs to have identical bits in the range 2^12 to 2^18. Signed-off-by: Martin Schwidefsky --- arch/s390/mm/mmap.c | 142 +++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 140 insertions(+), 2 deletions(-) (limited to 'arch/s390/mm/mmap.c') diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c index 9b436c21195e..d008f638b2cd 100644 --- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -28,8 +28,12 @@ #include #include #include +#include #include +unsigned long mmap_rnd_mask; +unsigned long mmap_align_mask; + static unsigned long stack_maxrandom_size(void) { if (!(current->flags & PF_RANDOMIZE)) @@ -60,8 +64,10 @@ static unsigned long mmap_rnd(void) { if (!(current->flags & PF_RANDOMIZE)) return 0; - /* 8MB randomization for mmap_base */ - return (get_random_int() & 0x7ffUL) << PAGE_SHIFT; + if (is_32bit_task()) + return (get_random_int() & 0x7ff) << PAGE_SHIFT; + else + return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT; } static unsigned long mmap_base_legacy(void) @@ -81,6 +87,106 @@ static inline unsigned long mmap_base(void) return STACK_TOP - stack_maxrandom_size() - mmap_rnd() - gap; } +unsigned long +arch_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + struct vm_unmapped_area_info info; + int do_color_align; + + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vma->vm_start)) + return addr; + } + + do_color_align = 0; + if (filp || (flags & MAP_SHARED)) + do_color_align = !is_32bit_task(); + + info.flags = 0; + info.length = len; + info.low_limit = mm->mmap_base; + info.high_limit = TASK_SIZE; + info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0; + info.align_offset = pgoff << PAGE_SHIFT; + return vm_unmapped_area(&info); +} + +unsigned long +arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, + const unsigned long len, const unsigned long pgoff, + const unsigned long flags) +{ + struct vm_area_struct *vma; + struct mm_struct *mm = current->mm; + unsigned long addr = addr0; + struct vm_unmapped_area_info info; + int do_color_align; + + /* requested length too big for entire address space */ + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + /* requesting a specific address */ + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vma->vm_start)) + return addr; + } + + do_color_align = 0; + if (filp || (flags & MAP_SHARED)) + do_color_align = !is_32bit_task(); + + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.length = len; + info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.high_limit = mm->mmap_base; + info.align_mask = do_color_align ? (mmap_align_mask << PAGE_SHIFT) : 0; + info.align_offset = pgoff << PAGE_SHIFT; + addr = vm_unmapped_area(&info); + + /* + * A failed mmap() very likely causes application failure, + * so fall back to the bottom-up function here. This scenario + * can happen with large stack limits and large mmap() + * allocations. + */ + if (addr & ~PAGE_MASK) { + VM_BUG_ON(addr != -ENOMEM); + info.flags = 0; + info.low_limit = TASK_UNMAPPED_BASE; + info.high_limit = TASK_SIZE; + addr = vm_unmapped_area(&info); + } + + return addr; +} + +unsigned long randomize_et_dyn(void) +{ + unsigned long base; + + base = (STACK_TOP / 3 * 2) & (~mmap_align_mask << PAGE_SHIFT); + return base + mmap_rnd(); +} + #ifndef CONFIG_64BIT /* @@ -177,4 +283,36 @@ void arch_pick_mmap_layout(struct mm_struct *mm) } } +static int __init setup_mmap_rnd(void) +{ + struct cpuid cpu_id; + + get_cpu_id(&cpu_id); + switch (cpu_id.machine) { + case 0x9672: + case 0x2064: + case 0x2066: + case 0x2084: + case 0x2086: + case 0x2094: + case 0x2096: + case 0x2097: + case 0x2098: + case 0x2817: + case 0x2818: + case 0x2827: + case 0x2828: + mmap_rnd_mask = 0x7ffUL; + mmap_align_mask = 0UL; + break; + case 0x2964: /* z13 */ + default: + mmap_rnd_mask = 0x3ff80UL; + mmap_align_mask = 0x7fUL; + break; + } + return 0; +} +early_initcall(setup_mmap_rnd); + #endif -- cgit From 4ba2815d3bf38d6a959d2d11b08cf862550dcfcc Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 12 Feb 2015 14:17:52 +0100 Subject: s390/mm: align 64-bit PIE binaries to 4GB The base address (STACK_TOP / 3 * 2) for a 64-bit program is two thirds into the 4GB segment at 0x2aa00000000. The randomization added on z13 can eat another 1GB of the remaining 1.33GB to the next 4GB boundary. In the worst case 300MB are left for the executable + bss which may cross into the next 4GB segment. This is bad for branch prediction, therefore align the base address to 4GB to give the program more room before it crosses the 4GB boundary. Signed-off-by: Martin Schwidefsky --- arch/s390/mm/mmap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/s390/mm/mmap.c') diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c index d008f638b2cd..179a2c20b01f 100644 --- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -183,7 +183,10 @@ unsigned long randomize_et_dyn(void) { unsigned long base; - base = (STACK_TOP / 3 * 2) & (~mmap_align_mask << PAGE_SHIFT); + base = STACK_TOP / 3 * 2; + if (!is_32bit_task()) + /* Align to 4GB */ + base &= ~((1UL << 32) - 1); return base + mmap_rnd(); } -- cgit