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From: Vladimir Murzin <vladimir.murzin@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: kbuild-all@01.org
Subject: [PATCH] ARM: virt: Relax arch timer version check during early boot
Date: Wed, 15 Jan 2020 14:16:38 +0000	[thread overview]
Message-ID: <1579097798-106243-1-git-send-email-vladimir.murzin@arm.com> (raw)

Updates to the Generic Timer architecture allow ID_PFR1.GenTimer to
have values other than 0 or 1. At the moment, Linux is quite strict in
the way it handles this field at early boot and will not configure
arch timer if it doesn't find the value 1.

Since here use ubfx for arch timer version extraction (hyb-stub build
with -march=armv7-a, so it is safe)

To help backports (even though the code was correct at the time of writing)
Fixes: 8ec58be9f3ff ("ARM: virt: arch_timers: enable access to physical timers")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 arch/arm/kernel/hyp-stub.S | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S
index ae50203..6607fa8 100644
--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -146,10 +146,9 @@ ARM_BE8(orr	r7, r7, #(1 << 25))     @ HSCTLR.EE
 #if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
 	@ make CNTP_* and CNTPCT accessible from PL1
 	mrc	p15, 0, r7, c0, c1, 1	@ ID_PFR1
-	lsr	r7, #16
-	and	r7, #0xf
-	cmp	r7, #1
-	bne	1f
+	ubfx	r7, r7, #16, #4
+	teq	r7, #0
+	beq	1f
 	mrc	p15, 4, r7, c14, c1, 0	@ CNTHCTL
 	orr	r7, r7, #3		@ PL1PCEN | PL1PCTEN
 	mcr	p15, 4, r7, c14, c1, 0	@ CNTHCTL
-- 
2.7.4


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WARNING: multiple messages have this Message-ID (diff)
From: Vladimir Murzin <vladimir.murzin@arm.com>
To: kbuild-all@lists.01.org
Subject: [PATCH] ARM: virt: Relax arch timer version check during early boot
Date: Wed, 15 Jan 2020 14:16:38 +0000	[thread overview]
Message-ID: <1579097798-106243-1-git-send-email-vladimir.murzin@arm.com> (raw)

[-- Attachment #1: Type: text/plain, Size: 1298 bytes --]

Updates to the Generic Timer architecture allow ID_PFR1.GenTimer to
have values other than 0 or 1. At the moment, Linux is quite strict in
the way it handles this field at early boot and will not configure
arch timer if it doesn't find the value 1.

Since here use ubfx for arch timer version extraction (hyb-stub build
with -march=armv7-a, so it is safe)

To help backports (even though the code was correct at the time of writing)
Fixes: 8ec58be9f3ff ("ARM: virt: arch_timers: enable access to physical timers")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
---
 arch/arm/kernel/hyp-stub.S | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S
index ae50203..6607fa8 100644
--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -146,10 +146,9 @@ ARM_BE8(orr	r7, r7, #(1 << 25))     @ HSCTLR.EE
 #if !defined(ZIMAGE) && defined(CONFIG_ARM_ARCH_TIMER)
 	@ make CNTP_* and CNTPCT accessible from PL1
 	mrc	p15, 0, r7, c0, c1, 1	@ ID_PFR1
-	lsr	r7, #16
-	and	r7, #0xf
-	cmp	r7, #1
-	bne	1f
+	ubfx	r7, r7, #16, #4
+	teq	r7, #0
+	beq	1f
 	mrc	p15, 4, r7, c14, c1, 0	@ CNTHCTL
 	orr	r7, r7, #3		@ PL1PCEN | PL1PCTEN
 	mcr	p15, 4, r7, c14, c1, 0	@ CNTHCTL
-- 
2.7.4

             reply	other threads:[~2020-01-15 14:17 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-15 14:16 Vladimir Murzin [this message]
2020-01-15 14:16 ` [PATCH] ARM: virt: Relax arch timer version check during early boot Vladimir Murzin
2020-01-20 10:46 ` Vladimir Murzin
2020-01-20 10:46   ` Vladimir Murzin
2020-01-20 11:14   ` Marc Zyngier
2020-01-20 11:14     ` Marc Zyngier
2020-01-20 11:34     ` Vladimir Murzin
2020-01-20 11:34       ` Vladimir Murzin
2020-01-20 11:56       ` Marc Zyngier
2020-01-20 11:56         ` Marc Zyngier

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