From: Kalesh Singh <kaleshsingh@google.com>
To: unlisted-recipients:; (no To-header on input)
Cc: will@kernel.org, maz@kernel.org, qperret@google.com,
tabba@google.com, surenb@google.com, kernel-team@android.com,
Kalesh Singh <kaleshsingh@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Joey Gouly <joey.gouly@arm.com>,
Peter Collingbourne <pcc@google.com>,
Andrew Scull <ascull@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: [PATCH v2 5/9] arm64: asm: Introduce test_sp_overflow macro
Date: Tue, 22 Feb 2022 08:51:06 -0800 [thread overview]
Message-ID: <20220222165212.2005066-6-kaleshsingh@google.com> (raw)
In-Reply-To: <20220222165212.2005066-1-kaleshsingh@google.com>
From: Quentin Perret <qperret@google.com>
The asm entry code in the kernel uses a trick to check if VMAP'd stacks
have overflowed by aligning them at THREAD_SHIFT * 2 granularity and
checking the SP's THREAD_SHIFT bit.
Protected KVM will soon make use of a similar trick to detect stack
overflows, so factor out the asm code in a re-usable macro.
Signed-off-by: Quentin Perret <qperret@google.com>
[Kalesh - Resolve minor conflicts]
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
arch/arm64/include/asm/assembler.h | 11 +++++++++++
arch/arm64/kernel/entry.S | 7 +------
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index e8bd0af0141c..ad40eb0eee83 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -850,4 +850,15 @@ alternative_endif
#endif /* GNU_PROPERTY_AARCH64_FEATURE_1_DEFAULT */
+/*
+ * Test whether the SP has overflowed, without corrupting a GPR.
+ */
+.macro test_sp_overflow shift, label
+ add sp, sp, x0 // sp' = sp + x0
+ sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp
+ tbnz x0, #\shift, \label
+ sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
+ sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
+.endm
+
#endif /* __ASM_ASSEMBLER_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 772ec2ecf488..ce99ee30c77e 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -53,15 +53,10 @@ alternative_else_nop_endif
sub sp, sp, #PT_REGS_SIZE
#ifdef CONFIG_VMAP_STACK
/*
- * Test whether the SP has overflowed, without corrupting a GPR.
* Task and IRQ stacks are aligned so that SP & (1 << THREAD_SHIFT)
* should always be zero.
*/
- add sp, sp, x0 // sp' = sp + x0
- sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp
- tbnz x0, #THREAD_SHIFT, 0f
- sub x0, sp, x0 // x0'' = sp' - x0' = (sp + x0) - sp = x0
- sub sp, sp, x0 // sp'' = sp' - x0 = (sp + x0) - x0 = sp
+ test_sp_overflow THREAD_SHIFT, 0f
b el\el\ht\()_\regsize\()_\label
0:
--
2.35.1.473.g83b2b277ed-goog
next prev parent reply other threads:[~2022-02-22 16:58 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-22 16:51 [PATCH v2 0/9] KVM: arm64: Hypervisor stack enhancements Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 1/9] KVM: arm64: Introduce hyp_alloc_private_va_range() Kalesh Singh
2022-02-22 18:53 ` Mark Rutland
2022-02-22 16:51 ` [PATCH v2 2/9] KVM: arm64: Introduce pkvm_alloc_private_va_range() Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 3/9] KVM: arm64: Add guard pages for KVM nVHE hypervisor stack Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 4/9] KVM: arm64: Add guard pages for pKVM (protected nVHE) " Kalesh Singh
2022-02-22 18:55 ` Mark Rutland
2022-02-22 20:30 ` Kalesh Singh
2022-02-22 16:51 ` Kalesh Singh [this message]
2022-02-22 18:32 ` [PATCH v2 5/9] arm64: asm: Introduce test_sp_overflow macro Mark Rutland
2022-02-22 20:20 ` Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 6/9] KVM: arm64: Detect and handle hypervisor stack overflows Kalesh Singh
2022-02-23 2:04 ` kernel test robot
2022-02-23 9:05 ` kernel test robot
2022-02-23 9:16 ` Marc Zyngier
2022-02-23 12:34 ` [kbuild-all] " Philip Li
2022-02-23 12:54 ` Marc Zyngier
2022-02-23 12:56 ` Ard Biesheuvel
2022-02-24 10:39 ` Marc Zyngier
2022-02-25 2:12 ` Chen, Rong A
2022-02-25 3:11 ` Kalesh Singh
2022-02-25 15:31 ` Marc Zyngier
2022-02-25 15:38 ` Ard Biesheuvel
2022-02-22 16:51 ` [PATCH v2 7/9] KVM: arm64: Add hypervisor overflow stack Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 8/9] KVM: arm64: Unwind and dump nVHE HYP stacktrace Kalesh Singh
2022-02-22 16:51 ` [PATCH v2 9/9] KVM: arm64: Symbolize the nVHE HYP backtrace Kalesh Singh
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