kernel: Store LiveUpdate location, use 1/4 of memory, make soft-reset arch neutral

Author: fwsGonzo

api/kernel/os.hpp

@@ -259,6 +259,7 @@ class OS {
 
   // XXX: Only used by solo5
   static RTC::timestamp_t booted_at_;
+  static uintptr_t liveupdate_loc_;
   static std::string version_str_;
   static std::string arch_str_;
   static Plugin_vec plugins_;

src/kernel/os.cpp

@@ -52,6 +52,7 @@ extern uintptr_t _ELF_END_;
 bool  OS::power_   = true;
 bool  OS::boot_sequence_passed_ = false;
 MHz   OS::cpu_mhz_ {-1};
+uintptr_t OS::liveupdate_loc_   = 0;
 uintptr_t OS::low_memory_size_  = 0;
 uintptr_t OS::high_memory_size_ = 0;
 uintptr_t OS::memory_end_ = 0;
@@ -75,8 +76,7 @@ std::string OS::arch_str_ = ARCH;
 
 void* OS::liveupdate_storage_area() noexcept
 {
-  // Default: 32MB below heap_max
-  return (void*) (OS::heap_max() & 0xFFFFFFF0 - 0x2000000);
+  return (void*) OS::liveupdate_loc_;
 }
 
 const std::string& OS::cmdline_args() noexcept
@@ -102,6 +102,13 @@ void OS::shutdown()
 
 void OS::post_start()
 {
+  if (OS::liveupdate_loc_ == 0)
+  {
+    // default size is 1/4 of heap from the end of memory
+    auto size = OS::heap_max() / 4;
+    OS::liveupdate_loc_ = (OS::heap_max() - size) & 0xFFFFFFF0;
+  }
+
   MYINFO("Initializing RNG");
   PROFILE("RNG init");
   RNG::init();

src/platform/x86_pc/idt.cpp

@@ -67,6 +67,7 @@ static void set_intr_entry(
 #ifdef ARCH_x86_64
   idt_entry->ist       = ist;
 #else
+  (void) ist;
   idt_entry->zero      = 0;
 #endif
 }

src/platform/x86_pc/softreset.cpp

@@ -13,11 +13,12 @@ namespace x86 {
 struct softreset_t
 {
   uint32_t  checksum;
-  uintptr_t high_mem;
+  uint64_t  liveupdate_loc;
+  uint64_t  high_mem;
   MHz       cpu_freq;
   uint32_t  apic_ticks;
-  void*     extra;
-  size_t    extra_len;
+  uint64_t  extra;
+  uint32_t  extra_len;
 };
 
 bool OS::is_softreset_magic(uint32_t value)
@@ -44,14 +45,15 @@ void OS::resume_softreset(intptr_t addr)
   data->checksum = csum_copy;
 
   /// restore known values
-  OS::memory_end_ = data->high_mem;
+  OS::liveupdate_loc_  = data->liveupdate_loc;
+  OS::memory_end_      = data->high_mem;
   OS::low_memory_size_ = 0x100000;
   OS::high_memory_size_ = OS::memory_end_ - 0x100000;
   OS::cpu_mhz_    = data->cpu_freq;
   x86::apic_timer_set_ticks(data->apic_ticks);
 
   /// call service-specific softreset handler
-  softreset_service_handler(data->extra, data->extra_len);
+  softreset_service_handler((void*) data->extra, data->extra_len);
 }
 
 extern "C"
@@ -60,10 +62,11 @@ void* __os_store_soft_reset(void* extra, size_t extra_len)
   // store softreset data in low memory
   auto* data = (softreset_t*) SOFT_RESET_LOCATION;
   data->checksum    = 0;
+  data->liveupdate_loc = (uintptr_t) OS::liveupdate_storage_area();
   data->high_mem    = OS::memory_end();
   data->cpu_freq    = OS::cpu_freq();
   data->apic_ticks  = x86::apic_timer_get_ticks();
-  data->extra       = extra;
+  data->extra       = (uint64_t) extra;
   data->extra_len   = extra_len;
 
   uint32_t csum = crc32_fast(data, sizeof(softreset_t));