Eliminate unnecessary stack copying. Add fake memmap entry.

src/vesper/x86/kickstart/kickstart.cpp

@@ -62,48 +62,6 @@ interrupt_descriptor_table_t interrupts_table;
 extern "C" void kickstart(multiboot_t::header_t* mbh);
 extern "C" address_t placement_address;
 extern "C" address_t KICKSTART_BASE;
-extern "C" address_t initial_esp; // in loader.s
-
-
-//! Remap stack for paging mode.
-/*!
-* Allocate enough pages to fit existing stack frame, copy data from old stack
-* and switch over to a new stack.
-* @todo Allocated stack pages are 1-1 mapped currently, but probably should be mapped
-* to some reserved stack area?
-* Changes the original stack given by the bootloader to one at
-* a virtual memory location defined at compile time.
-*/
-static void remap_stack()
-{
- address_t old_stack_pointer = read_stack_pointer();
- address_t old_base_pointer = read_base_pointer();
-
- size_t stack_size = initial_esp - old_stack_pointer;
- size_t stack_npages = page_align_up<address_t>(stack_size) / PAGE_SIZE;
- address_t stack_page = init_memmgr.alloc_next_page();
- init_memmgr.mapping_enter(stack_page, stack_page);
- for (size_t i = 1; i < stack_npages; i++)
- {
- address_t p = init_memmgr.alloc_next_page();
- init_memmgr.mapping_enter(p, p);
- }
-
- ia32_mmu_t::flush_page_directory();
-
- int offset = stack_page + stack_npages * PAGE_SIZE - initial_esp;
- address_t new_stack_pointer = old_stack_pointer + offset;
- address_t new_base_pointer = old_base_pointer + offset;
-
- kconsole.print("Copying stack from %p-%p to %p-%p (%d bytes)..", old_stack_pointer, initial_esp, new_stack_pointer, new_stack_pointer + stack_size, stack_size);
-
- memutils::copy_memory((void*)new_stack_pointer, (const void*)old_stack_pointer, stack_size);
-
- write_stack_pointer(new_stack_pointer);
- write_base_pointer(new_base_pointer);
-
- kconsole << "done. Activated new stack." << endl;
-}
 
 //! Prepare and boot system.
 /*!
@@ -139,16 +97,14 @@ void kickstart(multiboot_t::header_t* mbh)
  << "bootcp module at " << bootcp->mod_start << ", end " << bootcp->mod_end << endl
  << "Alloctn start at " << init_memmgr.get_alloced_start() << endl;
 
- // fake_mmap_entry->start = init_memmgr.get_alloced_start();
+ uint32_t fake_mmap_entry_start = init_memmgr.get_alloced_start();
 
  init_memmgr.setup_pagetables();
 
  address_t bootinfo_page = init_memmgr.alloc_next_page();
  init_memmgr.mapping_enter(bootinfo_page, bootinfo_page);
  mb.copy(bootinfo_page);
  bootinfo_t bootinfo(bootinfo_page);
- debugger_t::dump_memory(bootinfo_page, bootinfo.size());
-
  mb.set_header(bootinfo.multiboot_header());
 
  uint32_t k;
@@ -185,15 +141,23 @@ void kickstart(multiboot_t::header_t* mbh)
  interrupts_table.set_isr_handler(14, &page_fault_handler);
  interrupts_table.install();
 
- remap_stack();
+ // Map stack page
+ address_t old_stack_pointer = read_stack_pointer();
+ init_memmgr.mapping_enter(old_stack_pointer, old_stack_pointer);
 
  // Get kernel entry before enabling paging, as this area won't be mapped.
  typedef void (*kernel_entry)(bootinfo_t bi_page);
  kernel_entry init_nucleus = (kernel_entry)elf.get_entry_point();
 
- // TODO: We've allocated memory from a contiguous region, mark it and modify
+ // We've allocated memory from a contiguous region, mark it and modify
  // boot info page to exclude this region as occupied.
 
+ uint32_t fake_mmap_entry_end = init_memmgr.get_alloced_start();
+ multiboot_t::mmap_entry_t fake_mmap_entry;
+
+ fake_mmap_entry.set_region(fake_mmap_entry_start, fake_mmap_entry_end - fake_mmap_entry_start, multiboot_t::mmap_entry_t::bootinfo);
+ bootinfo.append_mmap_entry(&fake_mmap_entry);
+
  init_memmgr.start_paging();
 
  /// here we have paging enabled and can call kernel functions

src/vesper/x86/kickstart/loader.s

@@ -8,7 +8,6 @@
 ; jump to kickstart() in kickstart.cpp to do all the dirty job.
 ;
 global loader ; making entry point visible to linker
-global initial_esp
 extern kickstart
 extern KICKSTART_BASE
 extern data_end
@@ -25,6 +24,7 @@ CHECKSUM equ -(MAGIC + FLAGS) ; checksum required
 bits 32 ; 32 bit PM
 
 section .bss
+align 0x1000
 resb 0x1000
 initial_stack: ; reserve one page for startup stack
 
@@ -40,13 +40,10 @@ multiboot_header:
  dd bss_end
  dd loader
 
-initial_esp: dd 0 ; referencing initial_stack from C doesn't work :(
-
 section .text
 loader:
  cli
  mov esp, initial_stack
- mov [initial_esp], esp
  push ebx ; pass Multiboot info structure
 
  mov ebp, 0 ; make base pointer NULL here so we know

src/vesper/x86/lib/bootinfo.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "multiboot.h"
+#include "memory.h"
 
 /*!
 * Provide access to boot info page structures.
@@ -16,19 +17,44 @@ class bootinfo_t
 public:
  bootinfo_t(address_t bootinfo_page) : boot_info(bootinfo_page) {}
  size_t size();
+ void increase_size(size_t addend);
  multiboot_t::header_t* multiboot_header();
+ bool append_mmap_entry(multiboot_t::mmap_entry_t* entry);
 private:
  address_t boot_info;
 };
 
 inline size_t bootinfo_t::size()
 {
- return *reinterpret_cast<uint32_t*>(boot_info);
+ return *reinterpret_cast<size_t*>(boot_info);
+}
+
+inline void bootinfo_t::increase_size(size_t addend)
+{
+ (*reinterpret_cast<size_t*>(boot_info)) += addend;
 }
 
 inline multiboot_t::header_t* bootinfo_t::multiboot_header()
 {
- return reinterpret_cast<multiboot_t::header_t*>(boot_info + 4);
+ return reinterpret_cast<multiboot_t::header_t*>(boot_info + sizeof(size_t));
+}
+
+//TODO: move to bootinfo.cpp
+inline bool bootinfo_t::append_mmap_entry(multiboot_t::mmap_entry_t* entry)
+{
+ if (size() + sizeof(multiboot_t::mmap_entry_t) > PAGE_SIZE)
+ return false;
+
+ multiboot_t::header_t* header = multiboot_header();
+ uint32_t end = boot_info + size();
+ size_t entry_size = sizeof(multiboot_t::mmap_entry_t);
+
+ memutils::copy_memory(reinterpret_cast<void*>(end), entry, entry_size);
+ reinterpret_cast<multiboot_t::mmap_entry_t*>(end)->set_entry_size(entry_size); // ignore any extra fields
+ header->mmap.set_size(header->mmap.size() + entry_size);
+ increase_size(entry_size);
+
+ return true;
 }
 
 // kate: indent-width 4; replace-tabs on;