From: Pingfan Liu <kernelfans@gmail.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH 1/2] arm64: uaccess: disable preempt during uaccess through ttbr0
Date: Tue, 21 Dec 2021 21:42:41 +0800 [thread overview]
Message-ID: <20211221134242.98877-1-kernelfans@gmail.com> (raw)
If using software PAN, the ttbr0 should keep unchanged, otherwise,
considering the following scenario:
task1
__uaccess_ttbr0_enable()
switch_mm(this,next,tsk), which resets ttbr0 to __pa_symbol(reserved_pg_dir)
switch_mm(prev,this,tsk), which can not re-install the user page table automatically
Tackle this issue by disabling preemption.
Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
---
arch/arm64/include/asm/uaccess.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 3a5ff5e20586..406888877bbd 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -121,6 +121,7 @@ static inline bool uaccess_ttbr0_disable(void)
if (!system_uses_ttbr0_pan())
return false;
__uaccess_ttbr0_disable();
+ preempt_enable();
return true;
}
@@ -128,6 +129,7 @@ static inline bool uaccess_ttbr0_enable(void)
{
if (!system_uses_ttbr0_pan())
return false;
+ preempt_disable();
__uaccess_ttbr0_enable();
return true;
}
--
2.31.1
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next reply other threads:[~2021-12-21 13:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-21 13:42 Pingfan Liu [this message]
2021-12-21 13:42 ` [PATCH 2/2] arm64: uaccess: disable preempt during uaccess PSTATE.{PAN, TCO} Pingfan Liu
2021-12-22 13:02 ` [PATCH 2/2] arm64: uaccess: disable preempt during uaccess PSTATE.{PAN,TCO} Catalin Marinas
2021-12-23 9:39 ` Pingfan Liu
2021-12-22 12:59 ` [PATCH 1/2] arm64: uaccess: disable preempt during uaccess through ttbr0 Catalin Marinas
2021-12-23 9:36 ` Pingfan Liu
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