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arm64: mte: Define the number of bytes for storing the tags in a page

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Rather than explicitly calculating the number of bytes for a compact tag
storage format corresponding to a page, just add a MTE_PAGE_TAG_STORAGE
macro. With the current MTE implementation of 4 bits per tag, we store
2 tags in a byte.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Luis Machado <luis.machado@linaro.org>
Link: https://lore.kernel.org/r/20220131165456.2160675-4-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Catalin Marinas 2022-01-31 16:54:54 +00:00 committed by Will Deacon
parent 761b9b366c
commit ab1e435ca7
3 changed files with 4 additions and 3 deletions
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1
arch/arm64/include/asm/mte-def.h
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@ -11,6 +11,7 @@
#define MTE_TAG_SHIFT 56
#define MTE_TAG_SIZE 4
#define MTE_TAG_MASK GENMASK((MTE_TAG_SHIFT + (MTE_TAG_SIZE - 1)), MTE_TAG_SHIFT)
#define MTE_PAGE_TAG_STORAGE (MTE_GRANULES_PER_PAGE * MTE_TAG_SIZE / 8)
#define __MTE_PREAMBLE ARM64_ASM_PREAMBLE ".arch_extension memtag\n"

4
arch/arm64/lib/mte.S
View file

@ -134,7 +134,7 @@ SYM_FUNC_END(mte_copy_tags_to_user)
/*
* Save the tags in a page
* x0 - page address
* x1 - tag storage
* x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
*/
SYM_FUNC_START(mte_save_page_tags)
multitag_transfer_size x7, x5
@ -158,7 +158,7 @@ SYM_FUNC_END(mte_save_page_tags)
/*
* Restore the tags in a page
* x0 - page address
* x1 - tag storage
* x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes
*/
SYM_FUNC_START(mte_restore_page_tags)
multitag_transfer_size x7, x5

2
arch/arm64/mm/mteswap.c
View file

@ -12,7 +12,7 @@ static DEFINE_XARRAY(mte_pages);
void *mte_allocate_tag_storage(void)
{
/* tags granule is 16 bytes, 2 tags stored per byte */
return kmalloc(PAGE_SIZE / 16 / 2, GFP_KERNEL);
return kmalloc(MTE_PAGE_TAG_STORAGE, GFP_KERNEL);
}
void mte_free_tag_storage(char *storage)