zircon/kernel/phys/stack.cc

// Copyright 2020 The Fuchsia Authors
//
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file or at
// https://opensource.org/licenses/MIT

#include <phys/stack.h>

BootStack boot_stack, phys_exception_stack;
BootUnsafeStack boot_unsafe_stack, phys_exception_unsafe_stack;
BootShadowCallStack boot_shadow_call_stack, phys_exception_shadow_call_stack;

// This considers the limit to be "on".
bool BootStack::IsOnStack(uintptr_t sp) const {
  const uintptr_t base = reinterpret_cast<uintptr_t>(stack);
  return base <= sp && sp - base <= sizeof(stack);
}

#if __has_feature(shadow_call_stack)

bool BootShadowCallStack::IsOnStack(uintptr_t sp) const {
  const uintptr_t base = reinterpret_cast<uintptr_t>(shadow_call_stack);
  return base <= sp && sp - base <= sizeof(shadow_call_stack);
}

ShadowCallStackBacktrace BootShadowCallStack::BackTrace(uintptr_t scsp) const {
  if (scsp % sizeof(uintptr_t) == 0 && IsOnStack(scsp)) {
    const cpp20::span whole_stack(shadow_call_stack);
    const uintptr_t base = reinterpret_cast<uintptr_t>(shadow_call_stack);
    const size_t frames = (scsp - base) / sizeof(uintptr_t);
    return ShadowCallStackBacktrace(whole_stack.subspan(0, frames));
  }
  return {};
}

#endif  // __has_feature(shadow_call_stack)

bool IsOnStack(uintptr_t sp) {
  return boot_stack.IsOnStack(sp) || phys_exception_stack.IsOnStack(sp);
}