commit
1f6b83e5e4d3 ("s390: avoid z13 cache aliasing") checks for the
machine type to optimize address space randomization and zero page
allocation to avoid cache aliases.
This check might fail under a hypervisor with migration support.
z/VMs "Single System Image and Live Guest Relocation" facility will
"fake" the machine type of the oldest system in the group. For example
in a group of zEC12 and Z13 the guest appears to run on a zEC12
(architecture fencing within the relocation domain)
Remove the machine type detection and always use cache aliasing
rules that are known to work for all machines. These are the z13
aliasing rules.
Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
} while (0)
#endif /* CONFIG_COMPAT */
} while (0)
#endif /* CONFIG_COMPAT */
-extern unsigned long mmap_rnd_mask;
-
-#define STACK_RND_MASK (test_thread_flag(TIF_31BIT) ? 0x7ff : mmap_rnd_mask)
+/*
+ * Cache aliasing on the latest machines calls for a mapping granularity
+ * of 512KB. For 64-bit processes use a 512KB alignment and a randomization
+ * of up to 1GB. For 31-bit processes the virtual address space is limited,
+ * use no alignment and limit the randomization to 8MB.
+ */
+#define BRK_RND_MASK (is_32bit_task() ? 0x7ffUL : 0x3ffffUL)
+#define MMAP_RND_MASK (is_32bit_task() ? 0x7ffUL : 0x3ff80UL)
+#define MMAP_ALIGN_MASK (is_32bit_task() ? 0 : 0x7fUL)
+#define STACK_RND_MASK MMAP_RND_MASK
#define ARCH_DLINFO \
do { \
#define ARCH_DLINFO \
do { \
static inline unsigned long brk_rnd(void)
{
static inline unsigned long brk_rnd(void)
{
- /* 8MB for 32bit, 1GB for 64bit */
- if (is_32bit_task())
- return (get_random_int() & 0x7ffUL) << PAGE_SHIFT;
- else
- return (get_random_int() & 0x3ffffUL) << PAGE_SHIFT;
+ return (get_random_int() & BRK_RND_MASK) << PAGE_SHIFT;
}
unsigned long arch_randomize_brk(struct mm_struct *mm)
}
unsigned long arch_randomize_brk(struct mm_struct *mm)
static void __init setup_zero_pages(void)
{
static void __init setup_zero_pages(void)
{
unsigned int order;
struct page *page;
int i;
unsigned int order;
struct page *page;
int i;
- get_cpu_id(&cpu_id);
- switch (cpu_id.machine) {
- case 0x9672: /* g5 */
- case 0x2064: /* z900 */
- case 0x2066: /* z900 */
- case 0x2084: /* z990 */
- case 0x2086: /* z990 */
- case 0x2094: /* z9-109 */
- case 0x2096: /* z9-109 */
- order = 0;
- break;
- case 0x2097: /* z10 */
- case 0x2098: /* z10 */
- case 0x2817: /* z196 */
- case 0x2818: /* z196 */
- order = 2;
- break;
- case 0x2827: /* zEC12 */
- case 0x2828: /* zEC12 */
- order = 5;
- break;
- case 0x2964: /* z13 */
- default:
- order = 7;
- break;
- }
+ /* Latest machines require a mapping granularity of 512KB */
+ order = 7;
+
/* Limit number of empty zero pages for small memory sizes */
while (order > 2 && (totalram_pages >> 10) < (1UL << order))
order--;
/* Limit number of empty zero pages for small memory sizes */
while (order > 2 && (totalram_pages >> 10) < (1UL << order))
order--;
#include <linux/security.h>
#include <asm/pgalloc.h>
#include <linux/security.h>
#include <asm/pgalloc.h>
-unsigned long mmap_rnd_mask;
-static unsigned long mmap_align_mask;
-
static unsigned long stack_maxrandom_size(void)
{
if (!(current->flags & PF_RANDOMIZE))
static unsigned long stack_maxrandom_size(void)
{
if (!(current->flags & PF_RANDOMIZE))
unsigned long arch_mmap_rnd(void)
{
unsigned long arch_mmap_rnd(void)
{
- if (is_32bit_task())
- return (get_random_int() & 0x7ff) << PAGE_SHIFT;
- else
- return (get_random_int() & mmap_rnd_mask) << PAGE_SHIFT;
+ return (get_random_int() & MMAP_RND_MASK) << PAGE_SHIFT;
}
static unsigned long mmap_base_legacy(unsigned long rnd)
}
static unsigned long mmap_base_legacy(unsigned long rnd)
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct vm_unmapped_area_info info;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
struct vm_unmapped_area_info info;
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
if (len > TASK_SIZE - mmap_min_addr)
return -ENOMEM;
- 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.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;
+ if (filp || (flags & MAP_SHARED))
+ info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
+ else
+ info.align_mask = 0;
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
}
info.align_offset = pgoff << PAGE_SHIFT;
return vm_unmapped_area(&info);
}
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info;
struct mm_struct *mm = current->mm;
unsigned long addr = addr0;
struct vm_unmapped_area_info info;
/* requested length too big for entire address space */
if (len > TASK_SIZE - mmap_min_addr)
/* requested length too big for entire address space */
if (len > TASK_SIZE - mmap_min_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.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;
+ if (filp || (flags & MAP_SHARED))
+ info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
+ else
+ info.align_mask = 0;
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
info.align_offset = pgoff << PAGE_SHIFT;
addr = vm_unmapped_area(&info);
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}
mm->get_unmapped_area = s390_get_unmapped_area_topdown;
}
}
-
-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);