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| author | Freya Murphy <freya@freyacat.org> | 2025-04-20 11:26:32 -0400 |
|---|---|---|
| committer | Freya Murphy <freya@freyacat.org> | 2025-04-20 11:26:32 -0400 |
| commit | 5e0e6240ab058c490304e0789552b45160f900be (patch) | |
| tree | 82e19097301d3914f80e356710438278df24fd36 /kernel/entry.S | |
| parent | fix code segment (retfq) on long mode edge case (kvm) (diff) | |
| download | comus-5e0e6240ab058c490304e0789552b45160f900be.tar.gz comus-5e0e6240ab058c490304e0789552b45160f900be.tar.bz2 comus-5e0e6240ab058c490304e0789552b45160f900be.zip | |
fix term/gpu memory OOB error, add dynamic kernel identity map with N_IDENT_PTS
Diffstat (limited to 'kernel/entry.S')
| -rw-r--r-- | kernel/entry.S | 67 |
1 files changed, 40 insertions, 27 deletions
diff --git a/kernel/entry.S b/kernel/entry.S index 85cb350..e1b4767 100644 --- a/kernel/entry.S +++ b/kernel/entry.S @@ -1,10 +1,12 @@ +#include <comus/limits.h> + .globl _start .globl kernel_pml4 .globl kernel_pdpt_0 .globl kernel_pd_0 - .globl kernel_pt_0 + .globl kernel_pd_0_ents + .globl kernel_pd_1 .globl paging_pt - .globl bootstrap_pt .extern main .extern GDT @@ -66,17 +68,17 @@ mb_end: # kernel page tables .align 4096 -kernel_pml4: # reserve memory for initial 512 pml4 entires - .skip 4096 -kernel_pdpt_0: # reserve memory for initial 512 pdpt entires +kernel_pml4: .skip 4096 -kernel_pd_0: # reserve memory for initial 512 pd entries +kernel_pdpt_0: .skip 4096 -kernel_pt_0: # reserve memory for initial 512 pt entries +kernel_pd_0: .skip 4096 -paging_pt: # reserve pages for pager mappings +kernel_pd_0_ents: + .skip (4096*N_IDENT_PTS) +kernel_pd_1: .skip 4096 -bootstrap_pt: # reserve pages to bootstrap pager +paging_pt: .skip 4096 # kernel stack @@ -171,31 +173,39 @@ _start: pushl $0 push %eax - # zero out kernel page table - movl $kernel_pml4, %edi + # setup kernel paging structures + movl $kernel_pml4, %edi # zero out pml4 movl %edi, %cr3 xorl %eax, %eax - movl $4096, %ecx # zero 4096 pages + movl $0x1000, %ecx rep stosl movl %cr3, %edi - # identity map kernel - movl $kernel_pdpt_0 + 3, (%edi) # Set the uint32_t at the desination index to 0x2003. - movl $kernel_pdpt_0, %edi # Add 0x1000 to the desination index. - movl $kernel_pd_0 + 3, (%edi) # Set the uint32_t at the desination index to 0x3003. - movl $kernel_pd_0, %edi # Add 0x1000 to the desination index. - movl $kernel_pt_0 + 3, (%edi) # Set the uint32_t at the desination index to 0x4003. - movl $kernel_pt_0, %edi # Add 0x1000 to the desination index. + movl $kernel_pdpt_0 + 3, (%edi) # map pdpt + movl $kernel_pdpt_0, %edi + + movl $kernel_pd_0 + 3, (%edi) # map pd 0 + + addl $8, %edi # map pd 1 + movl $kernel_pd_1 + 3, (%edi) - movl $0x03, %ebx # Entry value to set - movl $512, %ecx # Loop count + movl $kernel_pd_0, %edi # map pd 0 ents + movl $kernel_pd_0_ents + 3, %ebx + movl $N_IDENT_PTS, %ecx +_start.map_pd_0: + movl %ebx, (%edi) + addl $(8 * 512), %ebx + addl $8, %edi + loop _start.map_pd_0 -_start.SetEntry: - # set entires in mapping - movl %ebx, (%edi) # Set the uint32_t at the desination index to the B-register - addl $0x1000, %ebx # Add 0x1000 to the B-register - addl $8, %edi # Add eight to the desination index - loop _start.SetEntry + movl $kernel_pd_0_ents, %edi # identity map kernel + movl $0x03, %ebx + movl $(512 * N_IDENT_PTS), %ecx +_start.map_pd_0_ents: + movl %ebx, (%edi) + addl $0x1000, %ebx + addl $8, %edi + loop _start.map_pd_0_ents # enable page address extension movl %cr4, %eax @@ -240,6 +250,9 @@ code64: # set segment registers movw $GDT.Data, %dx movw %dx, %ds + movw %dx, %es + movw %dx, %fs + movw %dx, %gs movw %dx, %ss # set ebp to 0 so we know where to end stack traces |