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From: Kalesh Singh <kaleshsingh@google.com>
Cc: mark.rutland@arm.com, broonie@kernel.org, will@kernel.org,
	maz@kernel.org,  qperret@google.com, tabba@google.com,
	surenb@google.com,  kernel-team@android.com,
	Kalesh Singh <kaleshsingh@google.com>,
	 James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Masami Hiramatsu <mhiramat@kernel.org>,
	Peter Collingbourne <pcc@google.com>,
	 Alexei Starovoitov <ast@kernel.org>,
	"Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>,
	 Andrew Jones <drjones@redhat.com>,
	Marco Elver <elver@google.com>,
	 Kefeng Wang <wangkefeng.wang@huawei.com>,
	Keir Fraser <keirf@google.com>,
	 Zenghui Yu <yuzenghui@huawei.com>,
	linux-arm-kernel@lists.infradead.org,
	 kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org
Subject: [PATCH v2 3/5] KVM: arm64: Add hypervisor overflow stack
Date: Mon,  2 May 2022 12:12:03 -0700	[thread overview]
Message-ID: <20220502191222.4192768-4-kaleshsingh@google.com> (raw)
In-Reply-To: <20220502191222.4192768-1-kaleshsingh@google.com>

Allocate and switch to 16-byte aligned secondary stack on overflow. This
provides us stack space to better handle overflows; and is used in
a subsequent patch to dump the hypervisor stacktrace.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 arch/arm64/kernel/stacktrace.c | 3 +++
 arch/arm64/kvm/hyp/nvhe/host.S | 9 ++-------
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index a84e38d41d38..f346b4c66f1c 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -242,4 +242,7 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
 
 	unwind(task, &state, consume_entry, cookie);
 }
+#else /* __KVM_NVHE_HYPERVISOR__ */
+DEFINE_PER_CPU(unsigned long [PAGE_SIZE/sizeof(long)], overflow_stack)
+	__aligned(16);
 #endif /* !__KVM_NVHE_HYPERVISOR__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 09b5254fb497..1cd2de4f039e 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -179,13 +179,8 @@ SYM_FUNC_END(__host_hvc)
 	b	hyp_panic
 
 .L__hyp_sp_overflow\@:
-	/*
-	 * Reset SP to the top of the stack, to allow handling the hyp_panic.
-	 * This corrupts the stack but is ok, since we won't be attempting
-	 * any unwinding here.
-	 */
-	ldr_this_cpu	x0, kvm_init_params + NVHE_INIT_STACK_HYP_VA, x1
-	mov	sp, x0
+	/* Switch to the overflow stack */
+	adr_this_cpu sp, overflow_stack + PAGE_SIZE, x0
 
 	b	hyp_panic_bad_stack
 	ASM_BUG()
-- 
2.36.0.464.gb9c8b46e94-goog


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  parent reply	other threads:[~2022-05-02 19:14 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-02 19:12 [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 1/5] KVM: arm64: Factor out common stack unwinding logic Kalesh Singh
2022-05-04 13:41   ` Mark Brown
2022-05-02 19:12 ` [PATCH v2 2/5] KVM: arm64: Compile stacktrace.nvhe.o Kalesh Singh
2022-05-04 14:16   ` Mark Brown
2022-05-04 16:02     ` Kalesh Singh
2022-05-02 19:12 ` Kalesh Singh [this message]
2022-05-02 19:12 ` [PATCH v2 4/5] KVM: arm64: Allocate shared stacktrace pages Kalesh Singh
2022-05-02 19:12 ` [PATCH v2 5/5] KVM: arm64: Unwind and dump nVHE hypervisor stacktrace Kalesh Singh

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