On hyp stack overflow switch to 16-byte aligned secondary stack.
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 <[email protected]>
---
arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
arch/arm64/kvm/hyp/nvhe/host.S | 9 ++-------
arch/arm64/kvm/hyp/nvhe/stacktrace.c | 11 +++++++++++
3 files changed, 14 insertions(+), 8 deletions(-)
create mode 100644 arch/arm64/kvm/hyp/nvhe/stacktrace.c
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index f9fe4dc21b1f..524e7dad5739 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -14,7 +14,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o \
- cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o
+ cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o
obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
obj-$(CONFIG_DEBUG_LIST) += list_debug.o
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index ea6a397b64a6..b6c0188c4b35 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -177,13 +177,8 @@ 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 + OVERFLOW_STACK_SIZE, x0
b hyp_panic_bad_stack
ASM_BUG()
diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
new file mode 100644
index 000000000000..a3d5b34e1249
--- /dev/null
+++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM nVHE hypervisor stack tracing support.
+ *
+ * Copyright (C) 2022 Google LLC
+ */
+#include <asm/memory.h>
+#include <asm/percpu.h>
+
+DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
+ __aligned(16);
--
2.37.0.170.g444d1eabd0-goog
Hi Kalesh,
On Fri, Jul 15, 2022 at 7:11 AM Kalesh Singh <[email protected]> wrote:
>
> On hyp stack overflow switch to 16-byte aligned secondary stack.
> 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 <[email protected]>
Reviewed-by: Fuad Tabba <[email protected]>
Thanks,
/fuad
> ---
> arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
> arch/arm64/kvm/hyp/nvhe/host.S | 9 ++-------
> arch/arm64/kvm/hyp/nvhe/stacktrace.c | 11 +++++++++++
> 3 files changed, 14 insertions(+), 8 deletions(-)
> create mode 100644 arch/arm64/kvm/hyp/nvhe/stacktrace.c
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index f9fe4dc21b1f..524e7dad5739 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -14,7 +14,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs))
>
> obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
> hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o \
> - cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o
> + cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o
> obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
> ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o
> obj-$(CONFIG_DEBUG_LIST) += list_debug.o
> diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
> index ea6a397b64a6..b6c0188c4b35 100644
> --- a/arch/arm64/kvm/hyp/nvhe/host.S
> +++ b/arch/arm64/kvm/hyp/nvhe/host.S
> @@ -177,13 +177,8 @@ 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 + OVERFLOW_STACK_SIZE, x0
>
> b hyp_panic_bad_stack
> ASM_BUG()
> diff --git a/arch/arm64/kvm/hyp/nvhe/stacktrace.c b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
> new file mode 100644
> index 000000000000..a3d5b34e1249
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * KVM nVHE hypervisor stack tracing support.
> + *
> + * Copyright (C) 2022 Google LLC
> + */
> +#include <asm/memory.h>
> +#include <asm/percpu.h>
> +
> +DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
> + __aligned(16);
> --
> 2.37.0.170.g444d1eabd0-goog
>