ref: 8cb33f2f18d8383fd78368110b3a78c7732da6f9
parent: e8111e517d0129f33594c4718691e41ced0b2018
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Tue Nov 17 18:18:08 EST 2020
pc/l.s: load virtual gdt pointer after mmu switch before removing the double map at 0, load our initial gdt pointer with its new KZERO based virtual address. this is prerequisite for handling traps early during bootup before mmuinit() loads the final gdt.
--- a/sys/src/9/pc/l.s
+++ b/sys/src/9/pc/l.s
@@ -71,8 +71,7 @@
STD
REP; MOVSB
MOVL BX, multibootptr-KZERO(SB)
- MOVL $_startPADDR(SB), AX
- ANDL $~KZERO, AX
+ MOVL $_startPADDR-KZERO(SB), AX
JMP* AX
/* multiboot structure pointer (physical address) */
@@ -98,8 +97,7 @@
CLI /* make sure interrupts are off */
/* set up the gdt so we have sane plan 9 style gdts. */
- MOVL $tgdtptr(SB), AX
- ANDL $~KZERO, AX
+ MOVL $tgdtptr-KZERO(SB), AX
MOVL (AX), GDTR
MOVW $1, AX
MOVW AX, MSW
@@ -158,9 +156,11 @@
WORD $(256*8-1)
LONG $IDTADDR
-TEXT mode32bit(SB), $0
- /* At this point, the GDT setup is done. */
+TEXT vtgdtptr(SB), $0
+ WORD $(3*8)
+ LONG $tgdt(SB)
+TEXT mode32bit(SB), $0
MOVL $((CPU0END-CPU0PDB)>>2), CX
MOVL $PADDR(CPU0PDB), DI
XORL AX, AX
@@ -231,6 +231,9 @@
* be initialised here.
*/
TEXT _startpg(SB), $0
+ MOVL $vtgdtptr(SB), AX
+ MOVL (AX), GDTR
+
MOVL $0, (PDO(0))(CX) /* undo double-map of KZERO at 0 */
MOVL CX, CR3 /* load and flush the mmu */
--
⑨