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author | Marc Zyngier <maz@kernel.org> | 2022-07-27 20:33:27 +0300 |
---|---|---|
committer | Marc Zyngier <maz@kernel.org> | 2022-07-27 20:33:27 +0300 |
commit | 0982c8d859f8f7022b9fd44d421c7ec721bb41f9 (patch) | |
tree | f6f9cb6622374da505eb728ab88e7a5f91c93583 /arch/arm64/kvm/hyp | |
parent | ae98a4a989935bb8e1431565e2eb86d7a19c2309 (diff) | |
parent | a4c750e2328a117dc9b19a2a61db0d4347902029 (diff) | |
download | linux-0982c8d859f8f7022b9fd44d421c7ec721bb41f9.tar.xz |
Merge branch kvm-arm64/nvhe-stacktrace into kvmarm-master/next
* kvm-arm64/nvhe-stacktrace: (27 commits)
: .
: Add an overflow stack to the nVHE EL2 code, allowing
: the implementation of an unwinder, courtesy of
: Kalesh Singh. From the cover letter (slightly edited):
:
: "nVHE has two modes of operation: protected (pKVM) and unprotected
: (conventional nVHE). Depending on the mode, a slightly different approach
: is used to dump the hypervisor stacktrace but the core unwinding logic
: remains the same.
:
: * Protected nVHE (pKVM) stacktraces:
:
: In protected nVHE mode, the host cannot directly access hypervisor memory.
:
: The hypervisor stack unwinding happens in EL2 and is made accessible to
: the host via a shared buffer. Symbolizing and printing the stacktrace
: addresses is delegated to the host and happens in EL1.
:
: * Non-protected (Conventional) nVHE stacktraces:
:
: In non-protected mode, the host is able to directly access the hypervisor
: stack pages.
:
: The hypervisor stack unwinding and dumping of the stacktrace is performed
: by the host in EL1, as this avoids the memory overhead of setting up
: shared buffers between the host and hypervisor."
:
: Additional patches from Oliver Upton and Marc Zyngier, tidying up
: the initial series.
: .
arm64: Update 'unwinder howto'
KVM: arm64: Don't open code ARRAY_SIZE()
KVM: arm64: Move nVHE-only helpers into kvm/stacktrace.c
KVM: arm64: Make unwind()/on_accessible_stack() per-unwinder functions
KVM: arm64: Move nVHE stacktrace unwinding into its own compilation unit
KVM: arm64: Move PROTECTED_NVHE_STACKTRACE around
KVM: arm64: Introduce pkvm_dump_backtrace()
KVM: arm64: Implement protected nVHE hyp stack unwinder
KVM: arm64: Save protected-nVHE (pKVM) hyp stacktrace
KVM: arm64: Stub implementation of pKVM HYP stack unwinder
KVM: arm64: Allocate shared pKVM hyp stacktrace buffers
KVM: arm64: Add PROTECTED_NVHE_STACKTRACE Kconfig
KVM: arm64: Introduce hyp_dump_backtrace()
KVM: arm64: Implement non-protected nVHE hyp stack unwinder
KVM: arm64: Prepare non-protected nVHE hypervisor stacktrace
KVM: arm64: Stub implementation of non-protected nVHE HYP stack unwinder
KVM: arm64: On stack overflow switch to hyp overflow_stack
arm64: stacktrace: Add description of stacktrace/common.h
arm64: stacktrace: Factor out common unwind()
arm64: stacktrace: Handle frame pointer from different address spaces
...
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'arch/arm64/kvm/hyp')
-rw-r--r-- | arch/arm64/kvm/hyp/nvhe/Makefile | 2 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/nvhe/host.S | 9 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/nvhe/stacktrace.c | 160 | ||||
-rw-r--r-- | arch/arm64/kvm/hyp/nvhe/switch.c | 6 |
4 files changed, 169 insertions, 8 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index a2b0d043dddf..ed5d222e2826 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -14,7 +14,7 @@ lib-objs := $(addprefix ../../../lib/, $(lib-objs)) hyp-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \ hyp-main.o hyp-smp.o psci-relay.o early_alloc.o page_alloc.o \ - cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o + cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \ ../fpsimd.o ../hyp-entry.o ../exception.o ../pgtable.o hyp-obj-$(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..58f645ad66bc --- /dev/null +++ b/arch/arm64/kvm/hyp/nvhe/stacktrace.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * KVM nVHE hypervisor stack tracing support. + * + * Copyright (C) 2022 Google LLC + */ +#include <asm/kvm_asm.h> +#include <asm/kvm_hyp.h> +#include <asm/memory.h> +#include <asm/percpu.h> + +DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack) + __aligned(16); + +DEFINE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info); + +/* + * hyp_prepare_backtrace - Prepare non-protected nVHE backtrace. + * + * @fp : frame pointer at which to start the unwinding. + * @pc : program counter at which to start the unwinding. + * + * Save the information needed by the host to unwind the non-protected + * nVHE hypervisor stack in EL1. + */ +static void hyp_prepare_backtrace(unsigned long fp, unsigned long pc) +{ + struct kvm_nvhe_stacktrace_info *stacktrace_info = this_cpu_ptr(&kvm_stacktrace_info); + struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params); + + stacktrace_info->stack_base = (unsigned long)(params->stack_hyp_va - PAGE_SIZE); + stacktrace_info->overflow_stack_base = (unsigned long)this_cpu_ptr(overflow_stack); + stacktrace_info->fp = fp; + stacktrace_info->pc = pc; +} + +#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE +#include <asm/stacktrace/nvhe.h> + +DEFINE_PER_CPU(unsigned long [NVHE_STACKTRACE_SIZE/sizeof(long)], pkvm_stacktrace); + +static bool on_overflow_stack(unsigned long sp, unsigned long size, + struct stack_info *info) +{ + unsigned long low = (unsigned long)this_cpu_ptr(overflow_stack); + unsigned long high = low + OVERFLOW_STACK_SIZE; + + return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info); +} + +static bool on_hyp_stack(unsigned long sp, unsigned long size, + struct stack_info *info) +{ + struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params); + unsigned long high = params->stack_hyp_va; + unsigned long low = high - PAGE_SIZE; + + return on_stack(sp, size, low, high, STACK_TYPE_HYP, info); +} + +static bool on_accessible_stack(const struct task_struct *tsk, + unsigned long sp, unsigned long size, + struct stack_info *info) +{ + if (info) + info->type = STACK_TYPE_UNKNOWN; + + return (on_overflow_stack(sp, size, info) || + on_hyp_stack(sp, size, info)); +} + +static int unwind_next(struct unwind_state *state) +{ + struct stack_info info; + + return unwind_next_common(state, &info, on_accessible_stack, NULL); +} + +static void notrace unwind(struct unwind_state *state, + stack_trace_consume_fn consume_entry, + void *cookie) +{ + while (1) { + int ret; + + if (!consume_entry(cookie, state->pc)) + break; + ret = unwind_next(state); + if (ret < 0) + break; + } +} + +/* + * pkvm_save_backtrace_entry - Saves a protected nVHE HYP stacktrace entry + * + * @arg : index of the entry in the stacktrace buffer + * @where : the program counter corresponding to the stack frame + * + * Save the return address of a stack frame to the shared stacktrace buffer. + * The host can access this shared buffer from EL1 to dump the backtrace. + */ +static bool pkvm_save_backtrace_entry(void *arg, unsigned long where) +{ + unsigned long *stacktrace = this_cpu_ptr(pkvm_stacktrace); + int *idx = (int *)arg; + + /* + * Need 2 free slots: 1 for current entry and 1 for the + * delimiter. + */ + if (*idx > ARRAY_SIZE(pkvm_stacktrace) - 2) + return false; + + stacktrace[*idx] = where; + stacktrace[++*idx] = 0UL; + + return true; +} + +/* + * pkvm_save_backtrace - Saves the protected nVHE HYP stacktrace + * + * @fp : frame pointer at which to start the unwinding. + * @pc : program counter at which to start the unwinding. + * + * Save the unwinded stack addresses to the shared stacktrace buffer. + * The host can access this shared buffer from EL1 to dump the backtrace. + */ +static void pkvm_save_backtrace(unsigned long fp, unsigned long pc) +{ + struct unwind_state state; + int idx = 0; + + kvm_nvhe_unwind_init(&state, fp, pc); + + unwind(&state, pkvm_save_backtrace_entry, &idx); +} +#else /* !CONFIG_PROTECTED_NVHE_STACKTRACE */ +static void pkvm_save_backtrace(unsigned long fp, unsigned long pc) +{ +} +#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */ + +/* + * kvm_nvhe_prepare_backtrace - prepare to dump the nVHE backtrace + * + * @fp : frame pointer at which to start the unwinding. + * @pc : program counter at which to start the unwinding. + * + * Saves the information needed by the host to dump the nVHE hypervisor + * backtrace. + */ +void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc) +{ + if (is_protected_kvm_enabled()) + pkvm_save_backtrace(fp, pc); + else + hyp_prepare_backtrace(fp, pc); +} diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c index ab0e19117dfe..9f6385702061 100644 --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -34,6 +34,8 @@ DEFINE_PER_CPU(struct kvm_host_data, kvm_host_data); DEFINE_PER_CPU(struct kvm_cpu_context, kvm_hyp_ctxt); DEFINE_PER_CPU(unsigned long, kvm_hyp_vector); +extern void kvm_nvhe_prepare_backtrace(unsigned long fp, unsigned long pc); + static void __activate_traps(struct kvm_vcpu *vcpu) { u64 val; @@ -375,6 +377,10 @@ asmlinkage void __noreturn hyp_panic(void) __sysreg_restore_state_nvhe(host_ctxt); } + /* Prepare to dump kvm nvhe hyp stacktrace */ + kvm_nvhe_prepare_backtrace((unsigned long)__builtin_frame_address(0), + _THIS_IP_); + __hyp_do_panic(host_ctxt, spsr, elr, par); unreachable(); } |