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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* KVM nVHE hypervisor stack tracing support.
*
* The unwinder implementation depends on the nVHE mode:
*
* 1) Non-protected nVHE mode - the host can directly access the
* HYP stack pages and unwind the HYP stack in EL1. This saves having
* to allocate shared buffers for the host to read the unwinded
* stacktrace.
*
* 2) pKVM (protected nVHE) mode - the host cannot directly access
* the HYP memory. The stack is unwinded in EL2 and dumped to a shared
* buffer where the host can read and print the stacktrace.
*
* Copyright (C) 2022 Google LLC
*/
#ifndef __ASM_STACKTRACE_NVHE_H
#define __ASM_STACKTRACE_NVHE_H
#include <asm/stacktrace/common.h>
/*
* kvm_nvhe_unwind_init - Start an unwind from the given nVHE HYP fp and pc
*
* @state : unwind_state to initialize
* @fp : frame pointer at which to start the unwinding.
* @pc : program counter at which to start the unwinding.
*/
static inline void kvm_nvhe_unwind_init(struct unwind_state *state,
unsigned long fp,
unsigned long pc)
{
unwind_init_common(state, NULL);
state->fp = fp;
state->pc = pc;
}
static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
struct stack_info *info);
static inline bool on_accessible_stack(const struct task_struct *tsk,
unsigned long sp, unsigned long size,
struct stack_info *info)
{
if (on_accessible_stack_common(tsk, sp, size, info))
return true;
if (on_hyp_stack(sp, size, info))
return true;
return false;
}
#ifdef __KVM_NVHE_HYPERVISOR__
/*
* Protected nVHE HYP stack unwinder
*
* In protected mode, the unwinding is done by the hypervisor in EL2.
*/
#ifdef CONFIG_PROTECTED_NVHE_STACKTRACE
static inline 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 inline 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 inline int notrace unwind_next(struct unwind_state *state)
{
struct stack_info info;
return unwind_next_common(state, &info, NULL);
}
NOKPROBE_SYMBOL(unwind_next);
#endif /* CONFIG_PROTECTED_NVHE_STACKTRACE */
#else /* !__KVM_NVHE_HYPERVISOR__ */
/*
* Conventional (non-protected) nVHE HYP stack unwinder
*
* In non-protected mode, the unwinding is done from kernel proper context
* (by the host in EL1).
*/
DECLARE_KVM_NVHE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
DECLARE_KVM_NVHE_PER_CPU(struct kvm_nvhe_stacktrace_info, kvm_stacktrace_info);
DECLARE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
/*
* kvm_nvhe_stack_kern_va - Convert KVM nVHE HYP stack addresses to a kernel VAs
*
* The nVHE hypervisor stack is mapped in the flexible 'private' VA range, to
* allow for guard pages below the stack. Consequently, the fixed offset address
* translation macros won't work here.
*
* The kernel VA is calculated as an offset from the kernel VA of the hypervisor
* stack base.
*
* Returns true on success and updates @addr to its corresponding kernel VA;
* otherwise returns false.
*/
static inline bool kvm_nvhe_stack_kern_va(unsigned long *addr,
enum stack_type type)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info;
unsigned long hyp_base, kern_base, hyp_offset;
stacktrace_info = this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
switch (type) {
case STACK_TYPE_HYP:
kern_base = (unsigned long)*this_cpu_ptr(&kvm_arm_hyp_stack_page);
hyp_base = (unsigned long)stacktrace_info->stack_base;
break;
case STACK_TYPE_OVERFLOW:
kern_base = (unsigned long)this_cpu_ptr_nvhe_sym(overflow_stack);
hyp_base = (unsigned long)stacktrace_info->overflow_stack_base;
break;
default:
return false;
}
hyp_offset = *addr - hyp_base;
*addr = kern_base + hyp_offset;
return true;
}
static inline bool on_overflow_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info
= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
unsigned long low = (unsigned long)stacktrace_info->overflow_stack_base;
unsigned long high = low + OVERFLOW_STACK_SIZE;
return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);
}
static inline bool on_hyp_stack(unsigned long sp, unsigned long size,
struct stack_info *info)
{
struct kvm_nvhe_stacktrace_info *stacktrace_info
= this_cpu_ptr_nvhe_sym(kvm_stacktrace_info);
unsigned long low = (unsigned long)stacktrace_info->stack_base;
unsigned long high = low + PAGE_SIZE;
return on_stack(sp, size, low, high, STACK_TYPE_HYP, info);
}
static inline int notrace unwind_next(struct unwind_state *state)
{
struct stack_info info;
return unwind_next_common(state, &info, kvm_nvhe_stack_kern_va);
}
NOKPROBE_SYMBOL(unwind_next);
void kvm_nvhe_dump_backtrace(unsigned long hyp_offset);
#endif /* __KVM_NVHE_HYPERVISOR__ */
#endif /* __ASM_STACKTRACE_NVHE_H */
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