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From: Kees Cook <keescook@chromium.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/2] arm64: cpufeature: Relocate PAN emulation report
Date: Wed, 21 Feb 2018 10:18:21 -0800	[thread overview]
Message-ID: <1519237102-46854-2-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1519237102-46854-1-git-send-email-keescook@chromium.org>

The PAN emulation notification was only happening for non-boot CPUs
if CPU capabilities had already been configured. This seems to be the
wrong place, as it's system-wide and isn't attached to capabilities,
so its reporting didn't normally happen. Instead, report it once from
the boot CPU.

Before (missing PAN emulation report):

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU: All CPU(s) started at EL2

After:

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU features: emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching
 CPU: All CPU(s) started at EL2

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/kernel/cpufeature.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 29b1f873e337..61aff55245ea 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1333,9 +1333,6 @@ static void verify_local_cpu_capabilities(void)
 
 	if (system_supports_sve())
 		verify_sve_features();
-
-	if (system_uses_ttbr0_pan())
-		pr_info("Emulating Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
 }
 
 void check_local_cpu_capabilities(void)
@@ -1394,6 +1391,9 @@ void __init setup_cpu_features(void)
 	if (system_supports_32bit_el0())
 		setup_elf_hwcaps(compat_elf_hwcaps);
 
+	if (system_uses_ttbr0_pan())
+		pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
+
 	sve_setup();
 
 	/* Advertise that we have computed the system capabilities */
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)
From: keescook@chromium.org (Kees Cook)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 1/2] arm64: cpufeature: Relocate PAN emulation report
Date: Wed, 21 Feb 2018 10:18:21 -0800	[thread overview]
Message-ID: <1519237102-46854-2-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1519237102-46854-1-git-send-email-keescook@chromium.org>

The PAN emulation notification was only happening for non-boot CPUs
if CPU capabilities had already been configured. This seems to be the
wrong place, as it's system-wide and isn't attached to capabilities,
so its reporting didn't normally happen. Instead, report it once from
the boot CPU.

Before (missing PAN emulation report):

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU: All CPU(s) started at EL2

After:

 SMP: Total of 4 processors activated.
 CPU features: detected feature: 32-bit EL0 Support
 CPU features: detected feature: Kernel page table isolation (KPTI)
 CPU features: emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching
 CPU: All CPU(s) started at EL2

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/kernel/cpufeature.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 29b1f873e337..61aff55245ea 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1333,9 +1333,6 @@ static void verify_local_cpu_capabilities(void)
 
 	if (system_supports_sve())
 		verify_sve_features();
-
-	if (system_uses_ttbr0_pan())
-		pr_info("Emulating Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
 }
 
 void check_local_cpu_capabilities(void)
@@ -1394,6 +1391,9 @@ void __init setup_cpu_features(void)
 	if (system_supports_32bit_el0())
 		setup_elf_hwcaps(compat_elf_hwcaps);
 
+	if (system_uses_ttbr0_pan())
+		pr_info("emulated: Privileged Access Never (PAN) using TTBR0_EL1 switching\n");
+
 	sve_setup();
 
 	/* Advertise that we have computed the system capabilities */
-- 
2.7.4

  reply	other threads:[~2018-02-21 18:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-21 18:18 [PATCH v2 0/2] arm64: cpufeature: Relocate PAN emulation report Kees Cook
2018-02-21 18:18 ` Kees Cook
2018-02-21 18:18 ` Kees Cook [this message]
2018-02-21 18:18   ` [PATCH v2 1/2] " Kees Cook
2018-02-21 18:18 ` [PATCH v2 2/2] arm64: cpufeature: Remove redundant "feature" in reports Kees Cook
2018-02-21 18:18   ` Kees Cook

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