Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 140/563] arm64: clear_page() shouldnt use DC ZVA when DCZID_EL0.DZP == 1 | Date | Mon, 24 Jan 2022 19:38:25 +0100 |
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From: Reiji Watanabe <reijiw@google.com>
[ 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: f27bb139c387 ("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> --- arch/arm64/lib/clear_page.S | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/arm64/lib/clear_page.S b/arch/arm64/lib/clear_page.S index b84b179edba3a..1fd5d790ab800 100644 --- a/arch/arm64/lib/clear_page.S +++ b/arch/arm64/lib/clear_page.S @@ -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) -- 2.34.1
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