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arm64: clear_page() shouldn't use DC ZVA when DCZID_EL0.DZP == 1

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[ Upstream commit f0616abd4e67143b45b04b565839148458857347 ]

Currently, clear_page() uses DC ZVA instruction unconditionally.  But it
should make sure that DCZID_EL0.DZP, which indicates whether or not use
of DC ZVA instruction is prohibited, is zero when using the instruction.
Use STNP instead when DCZID_EL0.DZP == 1.

Fixes: f27bb139c3 ("arm64: Miscellaneous library functions")
Signed-off-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20211206004736.1520989-2-reijiw@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Reiji Watanabe 2021-12-05 16:47:35 -08:00 committed by Greg Kroah-Hartman
parent 88ed31aab4
commit f0cb43a2c6
1 changed files with 10 additions and 0 deletions
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10
arch/arm64/lib/clear_page.S
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@ -16,6 +16,7 @@
*/
SYM_FUNC_START_PI(clear_page)
mrs x1, dczid_el0
tbnz x1, #4, 2f /* Branch if DC ZVA is prohibited */
and w1, w1, #0xf
mov x2, #4
lsl x1, x2, x1
@ -25,5 +26,14 @@ SYM_FUNC_START_PI(clear_page)
tst x0, #(PAGE_SIZE - 1)
b.ne 1b
ret
2: stnp xzr, xzr, [x0]
stnp xzr, xzr, [x0, #16]
stnp xzr, xzr, [x0, #32]
stnp xzr, xzr, [x0, #48]
add x0, x0, #64
tst x0, #(PAGE_SIZE - 1)
b.ne 2b
ret
SYM_FUNC_END_PI(clear_page)
EXPORT_SYMBOL(clear_page)