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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Mark Salter <msalter@redhat.com>, Will Deacon <will@kernel.org>,
	James Morse <james.morse@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Steve Capper <steve.capper@arm.com>,
	Anshuman Khandual <anshuman.khandual@arm.com>
Subject: [PATCH 5/5] arm64: mm: switch to 52-bit ID map on 52-bit VA capable systems
Date: Wed, 10 Mar 2021 18:15:15 +0100	[thread overview]
Message-ID: <20210310171515.416643-6-ardb@kernel.org> (raw)
In-Reply-To: <20210310171515.416643-1-ardb@kernel.org>

Now that we cleaned up the code a bit, add back the code path to use a
52-bit VA ID map on hardware that is 52-bit VA capable. This removes
a TCR update from the cpuidle path.

At the same time, make the 52-bit VA handling mutually exclusive with
the extended ID map code: a 52-bit VA kernel running on 48-bit VA only
hardware never has a need for it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/kernel/head.S | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index da6e99fa4e08..06f1ddeef821 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -303,8 +303,10 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
 	str	x5, [x6]
 	dmb	sy
 	dc	ivac, x6		// Invalidate potentially stale cache line
-#endif
 
+	mov	x5, TCR_T0SZ(VA_BITS)
+	b.eq	1f			// skip VA range extension on !LVA hardware
+#else
 	/*
 	 * VA_BITS may be too small to allow for an ID mapping to be created
 	 * that covers system RAM if that is located sufficiently high in the
@@ -321,6 +323,7 @@ SYM_FUNC_START_LOCAL(__create_page_tables)
 	clz	x5, x5
 	cmp	x5, TCR_T0SZ(VA_BITS_MIN) // default T0SZ small enough?
 	b.ge	1f			// .. then skip VA range extension
+#endif
 
 	adr_l	x6, idmap_t0sz
 	str	x5, [x6]
-- 
2.30.1


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  parent reply	other threads:[~2021-03-10 17:17 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-10 17:15 [PATCH 0/5] arm64: some 52-bit cleanups Ard Biesheuvel
2021-03-10 17:15 ` [PATCH 1/5] arm64: mm: use a 48-bit ID map when possible on 52-bit VA builds Ard Biesheuvel
2021-03-11  9:46   ` Will Deacon
2021-03-11 11:58     ` Ard Biesheuvel
2021-03-10 17:15 ` [PATCH 2/5] arm64: mm: remove unused __cpu_uses_extended_idmap[_level()] Ard Biesheuvel
2021-03-10 17:15 ` [PATCH 3/5] arm64: mm: use a compile time constant for vabits_actual when possible Ard Biesheuvel
2021-03-11  9:49   ` Will Deacon
2021-03-11 17:23     ` Ard Biesheuvel
2021-03-11 18:44       ` Will Deacon
2021-03-11 18:52         ` Ard Biesheuvel
2021-03-10 17:15 ` [PATCH 4/5] arm64: mm: get rid of idmap_ptrs_per_pgd handling Ard Biesheuvel
2021-03-10 17:15 ` Ard Biesheuvel [this message]
2021-03-11 13:26 ` [PATCH 0/5] arm64: some 52-bit cleanups Will Deacon

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