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s390/kasan: move memory needs estimation into a function

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Also correct rounding downs in estimation calculations.

Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2020-10-05 13:53:36 +02:00 committed by Heiko Carstens
parent e385b550fa
commit 0c4ec024a4
2 changed files with 34 additions and 22 deletions
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30
arch/s390/boot/kaslr.c
View File

@ -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;

26
arch/s390/include/asm/kasan.h
View File

@ -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