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Prekernel: Load multiboot values before loading kernel

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This makes sure we don't clobber multiboot structure before we need it
This commit is contained in:
Vladimir Serbinenko 2023-07-20 08:38:28 +02:00 committed by Andrew Kaster
parent d13609a607
commit 19cede9b3b
Notes: sideshowbarker 2024-07-17 11:29:41 +09:00 
Author: https://github.com/phcoder
Commit: https://github.com/SerenityOS/serenity/commit/19cede9b3b
Pull-request: https://github.com/SerenityOS/serenity/pull/20150
Reviewed-by: https://github.com/gmta
Reviewed-by: https://github.com/supercomputer7
1 changed files with 25 additions and 21 deletions
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46
Kernel/Prekernel/init.cpp
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@ -168,6 +168,31 @@ extern "C" [[noreturn]] void init()
boot_pd_kernel[511] = (FlatPtr)boot_pd_kernel_pt1023 | 0x3;
// Fill-in multiboot-related info before loading kernel as to avoid accidentally
// overwriting mbi end as to avoid to check whether it's mapped after reloading page tables.
BootInfo info {};
multiboot_info_ptr->mods_count--;
multiboot_info_ptr->mods_addr += sizeof(multiboot_module_entry_t);
auto adjust_by_mapping_base = [kernel_mapping_base](auto ptr) {
return (decltype(ptr))((FlatPtr)ptr + kernel_mapping_base);
};
info.multiboot_flags = multiboot_info_ptr->flags;
info.multiboot_memory_map = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mmap_addr);
info.multiboot_memory_map_count = multiboot_info_ptr->mmap_length / sizeof(multiboot_memory_map_t);
info.multiboot_modules = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mods_addr);
info.multiboot_modules_count = multiboot_info_ptr->mods_count;
if ((multiboot_info_ptr->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) != 0) {
info.multiboot_framebuffer_addr = multiboot_info_ptr->framebuffer_addr;
info.multiboot_framebuffer_pitch = multiboot_info_ptr->framebuffer_pitch;
info.multiboot_framebuffer_width = multiboot_info_ptr->framebuffer_width;
info.multiboot_framebuffer_height = multiboot_info_ptr->framebuffer_height;
info.multiboot_framebuffer_bpp = multiboot_info_ptr->framebuffer_bpp;
info.multiboot_framebuffer_type = multiboot_info_ptr->framebuffer_type;
}
reload_cr3();
int backwards = kernel_physical_base >= (FlatPtr)kernel_image;
@ -188,14 +213,6 @@ extern "C" [[noreturn]] void init()
__builtin_memset((u8*)kernel_load_base + kernel_program_header.p_vaddr + kernel_program_header.p_filesz, 0, kernel_program_header.p_memsz - kernel_program_header.p_filesz);
}
multiboot_info_ptr->mods_count--;
multiboot_info_ptr->mods_addr += sizeof(multiboot_module_entry_t);
auto adjust_by_mapping_base = [kernel_mapping_base](auto ptr) {
return (decltype(ptr))((FlatPtr)ptr + kernel_mapping_base);
};
BootInfo info {};
info.start_of_prekernel_image = (PhysicalPtr)start_of_prekernel_image;
info.end_of_prekernel_image = (PhysicalPtr)end_of_prekernel_image;
info.physical_to_virtual_offset = kernel_load_base - kernel_physical_base;
@ -211,19 +228,6 @@ extern "C" [[noreturn]] void init()
info.boot_pd_kernel = (PhysicalPtr)boot_pd_kernel;
info.boot_pd_kernel_pt1023 = (FlatPtr)adjust_by_mapping_base(boot_pd_kernel_pt1023);
info.kernel_cmdline = (FlatPtr)adjust_by_mapping_base(kernel_cmdline);
info.multiboot_flags = multiboot_info_ptr->flags;
info.multiboot_memory_map = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mmap_addr);
info.multiboot_memory_map_count = multiboot_info_ptr->mmap_length / sizeof(multiboot_memory_map_t);
info.multiboot_modules = adjust_by_mapping_base((FlatPtr)multiboot_info_ptr->mods_addr);
info.multiboot_modules_count = multiboot_info_ptr->mods_count;
if ((multiboot_info_ptr->flags & MULTIBOOT_INFO_FRAMEBUFFER_INFO) != 0) {
info.multiboot_framebuffer_addr = multiboot_info_ptr->framebuffer_addr;
info.multiboot_framebuffer_pitch = multiboot_info_ptr->framebuffer_pitch;
info.multiboot_framebuffer_width = multiboot_info_ptr->framebuffer_width;
info.multiboot_framebuffer_height = multiboot_info_ptr->framebuffer_height;
info.multiboot_framebuffer_bpp = multiboot_info_ptr->framebuffer_bpp;
info.multiboot_framebuffer_type = multiboot_info_ptr->framebuffer_type;
}
asm(
"mov %0, %%rax\n"