Commit 0c4ec024 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Heiko Carstens
Browse files

s390/kasan: move memory needs estimation into a function 



Also correct rounding downs in estimation calculations.

Reviewed-by: default avatarAlexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent e385b550

arch/s390/boot/kaslr.c

+8 −22
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <asm/cpacf.h>

#include <asm/timex.h>

#include <asm/sclp.h>

#include <asm/kasan.h>

#include "compressed/decompressor.h"

#include "boot.h"
@@ -179,34 +180,19 @@ unsigned long get_random_base(unsigned long safe_addr) 
	if (memory_end_set)

		memory_limit = min(memory_limit, memory_end);



	/*

	 * Avoid putting kernel in the end of physical memory

	 * which kasan will use for shadow memory and early pgtable

	 * mapping allocations.

	 */

	memory_limit -= kasan_estimate_memory_needs(memory_limit);



	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && INITRD_START && INITRD_SIZE) {

		if (safe_addr < INITRD_START + INITRD_SIZE)

			safe_addr = INITRD_START + INITRD_SIZE;

	}

	safe_addr = ALIGN(safe_addr, THREAD_SIZE);



	if ((IS_ENABLED(CONFIG_KASAN))) {

		/*

		 * Estimate kasan memory requirements, which it will reserve

		 * at the very end of available physical memory. To estimate

		 * that, we take into account that kasan would require

		 * 1/8 of available physical memory (for shadow memory) +

		 * creating page tables for the whole memory + shadow memory

		 * region (1 + 1/8). To keep page tables estimates simple take

		 * the double of combined ptes size.

		 */

		memory_limit = get_mem_detect_end();

		if (memory_end_set && memory_limit > memory_end)

			memory_limit = memory_end;



		/* for shadow memory */

		kasan_needs = memory_limit / 8;

		/* for paging structures */

		kasan_needs += (memory_limit + kasan_needs) / PAGE_SIZE /

			       _PAGE_ENTRIES * _PAGE_TABLE_SIZE * 2;

		memory_limit -= kasan_needs;

	}



	kernel_size = vmlinux.image_size + vmlinux.bss_size;

	if (safe_addr + kernel_size > memory_limit)

		return 0;

arch/s390/include/asm/kasan.h

+26 −0
Original line number Diff line number Diff line
@@ -17,10 +17,36 @@ extern void kasan_early_init(void); 
extern void kasan_copy_shadow_mapping(void);

extern void kasan_free_early_identity(void);

extern unsigned long kasan_vmax;



/*

 * Estimate kasan memory requirements, which it will reserve

 * at the very end of available physical memory. To estimate

 * that, we take into account that kasan would require

 * 1/8 of available physical memory (for shadow memory) +

 * creating page tables for the whole memory + shadow memory

 * region (1 + 1/8). To keep page tables estimates simple take

 * the double of combined ptes size.

 *

 * physmem parameter has to be already adjusted if not entire physical memory

 * would be used (e.g. due to effect of "mem=" option).

 */

static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem)

{

	unsigned long kasan_needs;

	unsigned long pages;

	/* for shadow memory */

	kasan_needs = round_up(physmem / 8, PAGE_SIZE);

	/* for paging structures */

	pages = DIV_ROUND_UP(physmem + kasan_needs, PAGE_SIZE);

	kasan_needs += DIV_ROUND_UP(pages, _PAGE_ENTRIES) * _PAGE_TABLE_SIZE * 2;



	return kasan_needs;

}

#else

static inline void kasan_early_init(void) { }

static inline void kasan_copy_shadow_mapping(void) { }

static inline void kasan_free_early_identity(void) { }

static inline unsigned long kasan_estimate_memory_needs(unsigned long physmem) { return 0; }

#endif



#endif