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From: Marc Zyngier <maz@kernel.org>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Cc: kernel-team@android.com,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Subject: [PATCH v2 3/4] KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr
Date: Wed, 10 Jun 2020 12:34:05 +0100	[thread overview]
Message-ID: <20200610113406.1493170-4-maz@kernel.org> (raw)
In-Reply-To: <20200610113406.1493170-1-maz@kernel.org>

Sparse complains that __hyp_this_cpu_ptr() returns something
that is flagged noderef and not in the correct address space
(both being the result of the __percpu annotation).

Pretend that __hyp_this_cpu_ptr() knows what it is doing by
forcefully casting the pointer with __kernel __force.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---

Notes:
    v2: Add __verify_pcpu_ptr() as suggested by Andrew Scull.

 arch/arm64/include/asm/kvm_asm.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 0c9b5fc4ba0a..d9b7da15dbca 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -81,12 +81,19 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
-/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+/*
+ * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
+ * provided that sym is really a *symbol* and not a pointer obtained from
+ * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
+ * sparse quiet.
+ */
 #define __hyp_this_cpu_ptr(sym)						\
 	({								\
-		void *__ptr = hyp_symbol_addr(sym);			\
+		void *__ptr;						\
+		__verify_pcpu_ptr(&sym);				\
+		__ptr = hyp_symbol_addr(sym);				\
 		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(&sym))__ptr;					\
+		(typeof(sym) __kernel __force *)__ptr;			\
 	 })
 
 #define __hyp_this_cpu_read(sym)					\
-- 
2.26.2

_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
	kernel-team@android.com,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	James Morse <james.morse@arm.com>,
	Andrew Scull <ascull@google.com>, Will Deacon <will@kernel.org>,
	Julien Thierry <julien.thierry.kdev@gmail.com>
Subject: [PATCH v2 3/4] KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr
Date: Wed, 10 Jun 2020 12:34:05 +0100	[thread overview]
Message-ID: <20200610113406.1493170-4-maz@kernel.org> (raw)
In-Reply-To: <20200610113406.1493170-1-maz@kernel.org>

Sparse complains that __hyp_this_cpu_ptr() returns something
that is flagged noderef and not in the correct address space
(both being the result of the __percpu annotation).

Pretend that __hyp_this_cpu_ptr() knows what it is doing by
forcefully casting the pointer with __kernel __force.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---

Notes:
    v2: Add __verify_pcpu_ptr() as suggested by Andrew Scull.

 arch/arm64/include/asm/kvm_asm.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 0c9b5fc4ba0a..d9b7da15dbca 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -81,12 +81,19 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
-/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+/*
+ * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
+ * provided that sym is really a *symbol* and not a pointer obtained from
+ * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
+ * sparse quiet.
+ */
 #define __hyp_this_cpu_ptr(sym)						\
 	({								\
-		void *__ptr = hyp_symbol_addr(sym);			\
+		void *__ptr;						\
+		__verify_pcpu_ptr(&sym);				\
+		__ptr = hyp_symbol_addr(sym);				\
 		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(&sym))__ptr;					\
+		(typeof(sym) __kernel __force *)__ptr;			\
 	 })
 
 #define __hyp_this_cpu_read(sym)					\
-- 
2.26.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Cc: James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Andrew Scull <ascull@google.com>,
	kernel-team@android.com
Subject: [PATCH v2 3/4] KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr
Date: Wed, 10 Jun 2020 12:34:05 +0100	[thread overview]
Message-ID: <20200610113406.1493170-4-maz@kernel.org> (raw)
In-Reply-To: <20200610113406.1493170-1-maz@kernel.org>

Sparse complains that __hyp_this_cpu_ptr() returns something
that is flagged noderef and not in the correct address space
(both being the result of the __percpu annotation).

Pretend that __hyp_this_cpu_ptr() knows what it is doing by
forcefully casting the pointer with __kernel __force.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---

Notes:
    v2: Add __verify_pcpu_ptr() as suggested by Andrew Scull.

 arch/arm64/include/asm/kvm_asm.h | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 0c9b5fc4ba0a..d9b7da15dbca 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -81,12 +81,19 @@ extern u32 __kvm_get_mdcr_el2(void);
 
 extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
 
-/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */
+/*
+ * Home-grown __this_cpu_{ptr,read} variants that always work at HYP,
+ * provided that sym is really a *symbol* and not a pointer obtained from
+ * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps
+ * sparse quiet.
+ */
 #define __hyp_this_cpu_ptr(sym)						\
 	({								\
-		void *__ptr = hyp_symbol_addr(sym);			\
+		void *__ptr;						\
+		__verify_pcpu_ptr(&sym);				\
+		__ptr = hyp_symbol_addr(sym);				\
 		__ptr += read_sysreg(tpidr_el2);			\
-		(typeof(&sym))__ptr;					\
+		(typeof(sym) __kernel __force *)__ptr;			\
 	 })
 
 #define __hyp_this_cpu_read(sym)					\
-- 
2.26.2


  parent reply	other threads:[~2020-06-10 11:34 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10 11:34 [PATCH v2 0/4] kvm: arm64: Pointer Authentication handling fixes Marc Zyngier
2020-06-10 11:34 ` Marc Zyngier
2020-06-10 11:34 ` Marc Zyngier
2020-06-10 11:34 ` [PATCH v2 1/4] KVM: arm64: Save the host's PtrAuth keys in non-preemptible context Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34 ` [PATCH v2 2/4] KVM: arm64: Handle PtrAuth traps early Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34 ` Marc Zyngier [this message]
2020-06-10 11:34   ` [PATCH v2 3/4] KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34 ` [PATCH v2 4/4] KVM: arm64: Remove host_cpu_context member from vcpu structure Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier
2020-06-10 11:34   ` Marc Zyngier

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