ref: c0cbe87b357a4464a7d10ab8f38a65c77ea3b629
dir: /os/pc/apbootstrap.s/
#include "mem.h" #define NOP BYTE $0x90 /* NOP */ #define LGDT(gdtptr) BYTE $0x0F; /* LGDT */ \ BYTE $0x01; BYTE $0x16; \ WORD $gdtptr #define FARJUMP16(s, o) BYTE $0xEA; /* far jump to ptr16:16 */ \ WORD $o; WORD $s; \ NOP; NOP; NOP #define FARJUMP32(s, o) BYTE $0x66; /* far jump to ptr32:16 */ \ BYTE $0xEA; LONG $o; WORD $s #define DELAY BYTE $0xEB; /* JMP .+2 */ \ BYTE $0x00 #define INVD BYTE $0x0F; BYTE $0x08 #define WBINVD BYTE $0x0F; BYTE $0x09 /* * Macros for calculating offsets within the page directory base * and page tables. Note that these are assembler-specific hence * the '<<2'. */ #define PDO(a) (((((a))>>22) & 0x03FF)<<2) #define PTO(a) (((((a))>>12) & 0x03FF)<<2) /* * Start an Application Processor. This must be placed on a 4KB boundary * somewhere in the 1st MB of conventional memory (APBOOTSTRAP). However, * due to some shortcuts below it's restricted further to within the 1st * 64KB. The AP starts in real-mode, with * CS selector set to the startup memory address/16; * CS base set to startup memory address; * CS limit set to 64KB; * CPL and IP set to 0. */ TEXT apbootstrap(SB), $0 FARJUMP16(0, _apbootstrap(SB)) TEXT _apvector(SB), $0 /* address APBOOTSTRAP+0x08 */ LONG $0 TEXT _appdb(SB), $0 /* address APBOOTSTRAP+0x0C */ LONG $0 TEXT _apapic(SB), $0 /* address APBOOTSTRAP+0x10 */ LONG $0 TEXT _apbootstrap(SB), $0 /* address APBOOTSTRAP+0x14 */ MOVW CS, AX MOVW AX, DS /* initialise DS */ LGDT(gdtptr(SB)) /* load a basic gdt */ MOVL CR0, AX ORL $1, AX MOVL AX, CR0 /* turn on protected mode */ DELAY /* JMP .+2 */ BYTE $0xB8; WORD $SELECTOR(1, SELGDT, 0)/* MOVW $SELECTOR(1, SELGDT, 0), AX */ MOVW AX, DS MOVW AX, ES MOVW AX, FS MOVW AX, GS MOVW AX, SS FARJUMP32(SELECTOR(2, SELGDT, 0), _ap32-KZERO(SB)) /* * For Pentiums and higher, the code that enables paging must come from * pages that are identity mapped. * To this end double map KZERO at virtual 0 and undo the mapping once virtual * nirvana has been obtained. */ TEXT _ap32(SB), $0 MOVL _appdb-KZERO(SB), CX /* physical address of PDB */ MOVL (PDO(KZERO))(CX), DX /* double-map KZERO at 0 */ MOVL DX, (PDO(0))(CX) MOVL CX, CR3 /* load and flush the mmu */ MOVL CR0, DX ORL $0x80010000, DX /* PG|WP */ ANDL $~0x6000000A, DX /* ~(CD|NW|TS|MP) */ MOVL $_appg(SB), AX MOVL DX, CR0 /* turn on paging */ JMP* AX TEXT _appg(SB), $0 MOVL CX, AX /* physical address of PDB */ ORL $KZERO, AX MOVL $0, (PDO(0))(AX) /* undo double-map of KZERO at 0 */ MOVL CX, CR3 /* load and flush the mmu */ MOVL $(MACHADDR+MACHSIZE-4), SP MOVL $0, AX PUSHL AX POPFL MOVL _apapic(SB), AX MOVL AX, (SP) MOVL _apvector(SB), AX CALL* AX _aphalt: HLT JMP _aphalt TEXT gdt(SB), $0 LONG $0x0000; LONG $0 LONG $0xFFFF; LONG $(SEGG|SEGB|(0xF<<16)|SEGP|SEGPL(0)|SEGDATA|SEGW) LONG $0xFFFF; LONG $(SEGG|SEGD|(0xF<<16)|SEGP|SEGPL(0)|SEGEXEC|SEGR) TEXT gdtptr(SB), $0 WORD $(3*8-1) LONG $gdt-KZERO(SB)