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arm64: mte: DC {GVA,GZVA} shouldn't be used when DCZID_EL0.DZP == 1

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Currently, mte_set_mem_tag_range() and mte_zero_clear_page_tags() use
DC {GVA,GZVA} unconditionally.  But, they should make sure that
DCZID_EL0.DZP, which indicates whether or not use of those instructions
is prohibited, is zero when using those instructions.
Use ST{G,ZG,Z2G} instead when DCZID_EL0.DZP == 1.

Fixes: 013bb59dbb ("arm64: mte: handle tags zeroing at page allocation time")
Fixes: 3d0cca0b02 ("kasan: speed up mte_set_mem_tag_range")
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Link: https://lore.kernel.org/r/20211206004736.1520989-3-reijiw@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Reiji Watanabe 2021-12-05 16:47:36 -08:00 committed by Catalin Marinas
parent f0616abd4e
commit 685e2564da
2 changed files with 12 additions and 4 deletions
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8
arch/arm64/include/asm/mte-kasan.h
View file

@ -84,10 +84,12 @@ static inline void __dc_gzva(u64 p)
static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag,
bool init)
{
u64 curr, mask, dczid_bs, end1, end2, end3;
u64 curr, mask, dczid, dczid_bs, dczid_dzp, end1, end2, end3;
/* Read DC G(Z)VA block size from the system register. */
dczid_bs = 4ul << (read_cpuid(DCZID_EL0) & 0xf);
dczid = read_cpuid(DCZID_EL0);
dczid_bs = 4ul << (dczid & 0xf);
dczid_dzp = (dczid >> 4) & 1;
curr = (u64)__tag_set(addr, tag);
mask = dczid_bs - 1;
@ -106,7 +108,7 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag,
*/
#define SET_MEMTAG_RANGE(stg_post, dc_gva) \
do { \
if (size >= 2 * dczid_bs) { \
if (!dczid_dzp && size >= 2 * dczid_bs) {\
do { \
curr = stg_post(curr); \
} while (curr < end1); \

8
arch/arm64/lib/mte.S
View file

@ -43,17 +43,23 @@ SYM_FUNC_END(mte_clear_page_tags)
* x0 - address to the beginning of the page
*/
SYM_FUNC_START(mte_zero_clear_page_tags)
and x0, x0, #(1 << MTE_TAG_SHIFT) - 1 // clear the tag
mrs x1, dczid_el0
tbnz x1, #4, 2f // Branch if DC GZVA is prohibited
and w1, w1, #0xf
mov x2, #4
lsl x1, x2, x1
and x0, x0, #(1 << MTE_TAG_SHIFT) - 1 // clear the tag
1: dc gzva, x0
add x0, x0, x1
tst x0, #(PAGE_SIZE - 1)
b.ne 1b
ret
2: stz2g x0, [x0], #(MTE_GRANULE_SIZE * 2)
tst x0, #(PAGE_SIZE - 1)
b.ne 2b
ret
SYM_FUNC_END(mte_zero_clear_page_tags)
/*