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Clear out/initialize IDT and GDT using their virtual addresses after

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they have been mapped. The previous method relied on their physical
pages living in the identity mapped region, which they wouldn't, when
the boot loader allocated enough memory before.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21610 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2007-07-15 00:54:16 +00:00
parent 119c6cdd0b
commit 018cf36396
1 changed files with 30 additions and 20 deletions
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50
src/system/boot/platform/bios_ia32/mmu.cpp
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@ -428,15 +428,16 @@ mmu_init_for_kernel(void)
TRACE(("idt at %p\n", idt));
// clear it out
for (int32 i = 0; i < IDT_LIMIT / 4; i++) {
idt[i] = 0;
}
// map the idt into virtual space
gKernelArgs.arch_args.vir_idt = (uint32)get_next_virtual_page();
map_page(gKernelArgs.arch_args.vir_idt, (uint32)idt, kDefaultPageFlags);
// clear it out
uint32* virtualIDT = (uint32*)gKernelArgs.arch_args.vir_idt;
for (int32 i = 0; i < IDT_LIMIT / 4; i++) {
virtualIDT[i] = 0;
}
// load the idt
idtDescriptor.limit = IDT_LIMIT - 1;
idtDescriptor.base = (uint32 *)gKernelArgs.arch_args.vir_idt;
@ -458,25 +459,34 @@ mmu_init_for_kernel(void)
TRACE(("gdt at %p\n", gdt));
// put standard segment descriptors in it
clear_segment_descriptor(&gdt[0]);
set_segment_descriptor(&gdt[1], 0, 0xffffffff, DT_CODE_READABLE, DPL_KERNEL);
// seg 0x08 - kernel 4GB code
set_segment_descriptor(&gdt[2], 0, 0xffffffff, DT_DATA_WRITEABLE, DPL_KERNEL);
// seg 0x10 - kernel 4GB data
set_segment_descriptor(&gdt[3], 0, 0xffffffff, DT_CODE_READABLE, DPL_USER);
// seg 0x1b - ring 3 user 4GB code
set_segment_descriptor(&gdt[4], 0, 0xffffffff, DT_DATA_WRITEABLE, DPL_USER);
// seg 0x23 - ring 3 user 4GB data
// gdt[5] and above will be filled later by the kernel
// to contain the TSS descriptors, and for TLS (one for every CPU)
// map the gdt into virtual space
gKernelArgs.arch_args.vir_gdt = (uint32)get_next_virtual_page();
map_page(gKernelArgs.arch_args.vir_gdt, (uint32)gdt, kDefaultPageFlags);
// put standard segment descriptors in it
segment_descriptor* virtualGDT
= (segment_descriptor*)gKernelArgs.arch_args.vir_gdt;
clear_segment_descriptor(&virtualGDT[0]);
// seg 0x08 - kernel 4GB code
set_segment_descriptor(&virtualGDT[1], 0, 0xffffffff, DT_CODE_READABLE,
DPL_KERNEL);
// seg 0x10 - kernel 4GB data
set_segment_descriptor(&virtualGDT[2], 0, 0xffffffff, DT_DATA_WRITEABLE,
DPL_KERNEL);
// seg 0x1b - ring 3 user 4GB code
set_segment_descriptor(&virtualGDT[3], 0, 0xffffffff, DT_CODE_READABLE,
DPL_USER);
// seg 0x23 - ring 3 user 4GB data
set_segment_descriptor(&virtualGDT[4], 0, 0xffffffff, DT_DATA_WRITEABLE,
DPL_USER);
// virtualGDT[5] and above will be filled later by the kernel
// to contain the TSS descriptors, and for TLS (one for every CPU)
// load the GDT
gdtDescriptor.limit = GDT_LIMIT - 1;
gdtDescriptor.base = (uint32 *)gKernelArgs.arch_args.vir_gdt;