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Commit 1f6b83e5 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent f8b2dcbd

arch/s390/include/asm/elf.h

+5 −3
Original line number Diff line number Diff line
@@ -163,8 +163,8 @@ extern unsigned int vdso_enabled; 
   the loader.  We need to make sure that it is out of the way of the program

   that it will "exec", and that there is sufficient room for the brk.  */



extern unsigned long randomize_et_dyn(unsigned long base);

#define ELF_ET_DYN_BASE		(randomize_et_dyn(STACK_TOP / 3 * 2))

extern unsigned long randomize_et_dyn(void);

#define ELF_ET_DYN_BASE		randomize_et_dyn()



/* This yields a mask that user programs can use to figure out what

   instruction set this CPU supports. */
@@ -209,7 +209,9 @@ do { \ 
} while (0)

#endif /* CONFIG_COMPAT */



#define STACK_RND_MASK	0x7ffUL

extern unsigned long mmap_rnd_mask;



#define STACK_RND_MASK	(mmap_rnd_mask)



#define ARCH_DLINFO							    \

do {									    \

arch/s390/include/asm/pgtable.h

+4 −0
Original line number Diff line number Diff line
@@ -1779,6 +1779,10 @@ extern int s390_enable_sie(void); 
extern int s390_enable_skey(void);

extern void s390_reset_cmma(struct mm_struct *mm);



/* s390 has a private copy of get unmapped area to deal with cache synonyms */

#define HAVE_ARCH_UNMAPPED_AREA

#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN



/*

 * No page table caches to initialise

 */

arch/s390/kernel/process.c

+0 −10
Original line number Diff line number Diff line
@@ -243,13 +243,3 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) 
	ret = PAGE_ALIGN(mm->brk + brk_rnd());

	return (ret > mm->brk) ? ret : mm->brk;

}
 


unsigned long randomize_et_dyn(unsigned long base)

{

	unsigned long ret;



	if (!(current->flags & PF_RANDOMIZE))

		return base;

	ret = PAGE_ALIGN(base + brk_rnd());

	return (ret > base) ? ret : base;

}

arch/s390/mm/init.c

+6 −3
Original line number Diff line number Diff line
@@ -71,13 +71,16 @@ static void __init setup_zero_pages(void) 
		break;

	case 0x2827:	/* zEC12 */

	case 0x2828:	/* zEC12 */

	default:

		order = 5;

		break;

	case 0x2964:	/* z13 */

	default:

		order = 7;

		break;

	}

	/* Limit number of empty zero pages for small memory sizes */

	if (order > 2 && totalram_pages <= 16384)

		order = 2;

	while (order > 2 && (totalram_pages >> 10) < (1UL << order))

		order--;



	empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);

	if (!empty_zero_page)

arch/s390/mm/mmap.c

+140 −2
Original line number Diff line number Diff line
@@ -28,8 +28,12 @@ 
#include <linux/module.h>

#include <linux/random.h>

#include <linux/compat.h>

#include <linux/security.h>

#include <asm/pgalloc.h>



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