x86_64/cpu: improve stack overflow detection

2 files changed, 29 insertions, 2 deletions

diff --git a/arch/x86_64/arch/cpu/interrupts.cpp b/arch/x86_64/arch/cpu/interrupts.cpp
index 94806621..f27c3a2e 100644
--- a/arch/x86_64/arch/cpu/interrupts.cpp
+++ b/arch/x86_64/arch/cpu/interrupts.cpp
@@ -9,7 +9,9 @@
 #include <kapi/system.hpp>
 
 #include <kstd/print.hpp>
+#include <kstd/units.hpp>
 
+#include <cstddef>
 #include <cstdint>
 
 namespace arch::cpu
@@ -17,6 +19,9 @@ namespace arch::cpu
 
   namespace
   {
+    extern "C" std::byte __kernel_stack_bottom[];  // NOLINT(readability-identifier-naming)
+    extern "C" std::byte __ist1_stack_bottom[];    // NOLINT(readability-identifier-naming)
+
     enum struct exception
     {
       divide_error,
@@ -128,8 +133,28 @@ namespace arch::cpu
 
     auto handle_double_fault(interrupt_frame * frame) -> void
     {
-      kapi::system::panic("[ARCH:CPU] Double fault! Possible kernel stack corruption! rsp was {}",
-                          frame->cpu_saved.rsp);
+      auto const rsp = frame->cpu_saved.rsp;
+      auto const rip = frame->cpu_saved.rip;
+      auto const kernel_stack_bottom = kapi::memory::linear_address{__kernel_stack_bottom};
+      auto const ist1_stack_bottom = kapi::memory::linear_address{__ist1_stack_bottom};
+
+      auto const overflowed_kernel = rsp < kernel_stack_bottom && rsp >= kernel_stack_bottom - kapi::memory::page::size;
+      auto const overflowed_ist1 = rsp < ist1_stack_bottom && rsp >= ist1_stack_bottom - kapi::memory::page::size;
+
+      if (overflowed_kernel || overflowed_ist1)
+      {
+        auto const overflowed_what = overflowed_kernel ? "kernel" : "ist1";
+        auto const overflowed_by =
+            kstd::bytes{static_cast<std::size_t>((overflowed_kernel ? kernel_stack_bottom : ist1_stack_bottom) - rsp)};
+
+        kapi::system::panic("[ARCH:CPU] Suspected {} stack overflow: \n"  //
+                            "\toverflowed by: {:#}\n"                     //
+                            "\trsp: {}\n"                                 //
+                            "\trip: {}\n",                                //
+                            overflowed_what, overflowed_by, rsp, rip);
+      }
+
+      kapi::system::panic("[ARCH:CPU] Double fault at {}", rip);
     }
   }  // namespace
 
diff --git a/arch/x86_64/scripts/kernel.ld b/arch/x86_64/scripts/kernel.ld
index 8cd6c1c3..f96152d7 100644
--- a/arch/x86_64/scripts/kernel.ld
+++ b/arch/x86_64/scripts/kernel.ld
@@ -100,6 +100,7 @@ SECTIONS
 
   .kernel_stack ALIGN(4K) : AT (ADDR (.kernel_stack) - TEACHOS_VMA)
   {
+    PROVIDE_HIDDEN(__kernel_stack_bottom = .);
     *(.stack)
   } :kernel_data
 
@@ -107,6 +108,7 @@ SECTIONS
 
   .kernel_ist1_stack ALIGN(4K) : AT (ADDR (.kernel_ist1_stack) - TEACHOS_VMA)
   {
+    PROVIDE_HIDDEN(__ist1_stack_bottom = .);
     *(.ist1_stack)
   } :kernel_data