327 lines
11 KiB
C
Executable file
327 lines
11 KiB
C
Executable file
/* This file contains code for initialization of protected mode, to initialize
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* code and data segment descriptors, and to initialize global descriptors
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* for local descriptors in the process table.
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*/
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#include "../../kernel.h"
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#include "../../proc.h"
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#include <archconst.h>
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#include "proto.h"
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#define INT_GATE_TYPE (INT_286_GATE | DESC_386_BIT)
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#define TSS_TYPE (AVL_286_TSS | DESC_386_BIT)
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struct desctableptr_s {
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char limit[sizeof(u16_t)];
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char base[sizeof(u32_t)]; /* really u24_t + pad for 286 */
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};
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struct gatedesc_s {
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u16_t offset_low;
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u16_t selector;
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u8_t pad; /* |000|XXXXX| ig & trpg, |XXXXXXXX| task g */
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u8_t p_dpl_type; /* |P|DL|0|TYPE| */
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u16_t offset_high;
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};
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struct tss_s {
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reg_t backlink;
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reg_t sp0; /* stack pointer to use during interrupt */
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reg_t ss0; /* " segment " " " " */
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reg_t sp1;
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reg_t ss1;
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reg_t sp2;
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reg_t ss2;
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reg_t cr3;
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reg_t ip;
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reg_t flags;
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reg_t ax;
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reg_t cx;
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reg_t dx;
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reg_t bx;
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reg_t sp;
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reg_t bp;
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reg_t si;
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reg_t di;
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reg_t es;
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reg_t cs;
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reg_t ss;
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reg_t ds;
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reg_t fs;
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reg_t gs;
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reg_t ldt;
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u16_t trap;
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u16_t iobase;
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/* u8_t iomap[0]; */
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};
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PUBLIC struct segdesc_s gdt[GDT_SIZE]; /* used in klib.s and mpx.s */
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PRIVATE struct gatedesc_s idt[IDT_SIZE]; /* zero-init so none present */
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PUBLIC struct tss_s tss; /* zero init */
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FORWARD _PROTOTYPE( void int_gate, (unsigned vec_nr, vir_bytes offset,
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unsigned dpl_type) );
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FORWARD _PROTOTYPE( void sdesc, (struct segdesc_s *segdp, phys_bytes base,
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vir_bytes size) );
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/*===========================================================================*
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* enable_iop *
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*===========================================================================*/
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PUBLIC void enable_iop(struct proc *pp)
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{
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/* Allow a user process to use I/O instructions. Change the I/O Permission
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* Level bits in the psw. These specify least-privileged Current Permission
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* Level allowed to execute I/O instructions. Users and servers have CPL 3.
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* You can't have less privilege than that. Kernel has CPL 0, tasks CPL 1.
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*/
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pp->p_reg.psw |= 0x3000;
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}
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/*===========================================================================*
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* seg2phys *
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*===========================================================================*/
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PUBLIC phys_bytes seg2phys(U16_t seg)
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{
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/* Return the base address of a segment, with seg being a
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* register, or a 286/386 segment selector.
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*/
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phys_bytes base;
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struct segdesc_s *segdp;
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segdp = &gdt[seg >> 3];
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base = ((u32_t) segdp->base_low << 0)
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| ((u32_t) segdp->base_middle << 16)
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| ((u32_t) segdp->base_high << 24);
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return base;
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}
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/*===========================================================================*
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* phys2seg *
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*===========================================================================*/
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PUBLIC void phys2seg(u16_t *seg, vir_bytes *off, phys_bytes phys)
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{
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/* Return a segment selector and offset that can be used to reach a physical
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* address, for use by a driver doing memory I/O in the A0000 - DFFFF range.
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*/
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*seg = FLAT_DS_SELECTOR;
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*off = phys;
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}
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/*===========================================================================*
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* init_dataseg *
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*===========================================================================*/
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PUBLIC void init_dataseg(register struct segdesc_s *segdp,
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phys_bytes base, vir_bytes size, int privilege)
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{
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/* Build descriptor for a data segment. */
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sdesc(segdp, base, size);
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segdp->access = (privilege << DPL_SHIFT) | (PRESENT | SEGMENT |
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WRITEABLE);
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/* EXECUTABLE = 0, EXPAND_DOWN = 0, ACCESSED = 0 */
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}
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/*===========================================================================*
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* init_codeseg *
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*===========================================================================*/
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PUBLIC void init_codeseg(register struct segdesc_s *segdp, phys_bytes base,
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vir_bytes size, int privilege)
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{
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/* Build descriptor for a code segment. */
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sdesc(segdp, base, size);
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segdp->access = (privilege << DPL_SHIFT)
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| (PRESENT | SEGMENT | EXECUTABLE | READABLE);
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/* CONFORMING = 0, ACCESSED = 0 */
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}
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/*===========================================================================*
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* prot_init *
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*===========================================================================*/
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PUBLIC void prot_init(void)
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{
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/* Set up tables for protected mode.
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* All GDT slots are allocated at compile time.
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*/
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struct gate_table_s *gtp;
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struct desctableptr_s *dtp;
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unsigned ldt_index;
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register struct proc *rp;
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static struct gate_table_s {
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_PROTOTYPE( void (*gate), (void) );
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unsigned char vec_nr;
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unsigned char privilege;
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}
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gate_table[] = {
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{ divide_error, DIVIDE_VECTOR, INTR_PRIVILEGE },
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{ single_step_exception, DEBUG_VECTOR, INTR_PRIVILEGE },
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{ nmi, NMI_VECTOR, INTR_PRIVILEGE },
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{ breakpoint_exception, BREAKPOINT_VECTOR, USER_PRIVILEGE },
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{ overflow, OVERFLOW_VECTOR, USER_PRIVILEGE },
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{ bounds_check, BOUNDS_VECTOR, INTR_PRIVILEGE },
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{ inval_opcode, INVAL_OP_VECTOR, INTR_PRIVILEGE },
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{ copr_not_available, COPROC_NOT_VECTOR, INTR_PRIVILEGE },
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{ double_fault, DOUBLE_FAULT_VECTOR, INTR_PRIVILEGE },
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{ copr_seg_overrun, COPROC_SEG_VECTOR, INTR_PRIVILEGE },
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{ inval_tss, INVAL_TSS_VECTOR, INTR_PRIVILEGE },
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{ segment_not_present, SEG_NOT_VECTOR, INTR_PRIVILEGE },
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{ stack_exception, STACK_FAULT_VECTOR, INTR_PRIVILEGE },
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{ general_protection, PROTECTION_VECTOR, INTR_PRIVILEGE },
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{ page_fault, PAGE_FAULT_VECTOR, INTR_PRIVILEGE },
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{ copr_error, COPROC_ERR_VECTOR, INTR_PRIVILEGE },
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{ hwint00, VECTOR( 0), INTR_PRIVILEGE },
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{ hwint01, VECTOR( 1), INTR_PRIVILEGE },
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{ hwint02, VECTOR( 2), INTR_PRIVILEGE },
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{ hwint03, VECTOR( 3), INTR_PRIVILEGE },
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{ hwint04, VECTOR( 4), INTR_PRIVILEGE },
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{ hwint05, VECTOR( 5), INTR_PRIVILEGE },
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{ hwint06, VECTOR( 6), INTR_PRIVILEGE },
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{ hwint07, VECTOR( 7), INTR_PRIVILEGE },
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{ hwint08, VECTOR( 8), INTR_PRIVILEGE },
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{ hwint09, VECTOR( 9), INTR_PRIVILEGE },
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{ hwint10, VECTOR(10), INTR_PRIVILEGE },
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{ hwint11, VECTOR(11), INTR_PRIVILEGE },
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{ hwint12, VECTOR(12), INTR_PRIVILEGE },
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{ hwint13, VECTOR(13), INTR_PRIVILEGE },
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{ hwint14, VECTOR(14), INTR_PRIVILEGE },
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{ hwint15, VECTOR(15), INTR_PRIVILEGE },
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{ s_call, SYS386_VECTOR, USER_PRIVILEGE }, /* 386 system call */
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{ level0_call, LEVEL0_VECTOR, TASK_PRIVILEGE },
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};
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/* Build gdt and idt pointers in GDT where the BIOS expects them. */
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dtp= (struct desctableptr_s *) &gdt[GDT_INDEX];
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* (u16_t *) dtp->limit = (sizeof gdt) - 1;
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* (u32_t *) dtp->base = vir2phys(gdt);
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dtp= (struct desctableptr_s *) &gdt[IDT_INDEX];
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* (u16_t *) dtp->limit = (sizeof idt) - 1;
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* (u32_t *) dtp->base = vir2phys(idt);
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/* Build segment descriptors for tasks and interrupt handlers. */
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init_codeseg(&gdt[CS_INDEX],
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kinfo.code_base, kinfo.code_size, INTR_PRIVILEGE);
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init_dataseg(&gdt[DS_INDEX],
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kinfo.data_base, kinfo.data_size, INTR_PRIVILEGE);
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init_dataseg(&gdt[ES_INDEX], 0L, 0, TASK_PRIVILEGE);
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/* Build scratch descriptors for functions in klib88. */
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init_dataseg(&gdt[DS_286_INDEX], 0L, 0, TASK_PRIVILEGE);
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init_dataseg(&gdt[ES_286_INDEX], 0L, 0, TASK_PRIVILEGE);
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/* Build local descriptors in GDT for LDT's in process table.
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* The LDT's are allocated at compile time in the process table, and
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* initialized whenever a process' map is initialized or changed.
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*/
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for (rp = BEG_PROC_ADDR, ldt_index = FIRST_LDT_INDEX;
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rp < END_PROC_ADDR; ++rp, ldt_index++) {
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init_dataseg(&gdt[ldt_index], vir2phys(rp->p_seg.p_ldt),
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sizeof(rp->p_seg.p_ldt), INTR_PRIVILEGE);
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gdt[ldt_index].access = PRESENT | LDT;
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rp->p_seg.p_ldt_sel = ldt_index * DESC_SIZE;
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}
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/* Build main TSS.
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* This is used only to record the stack pointer to be used after an
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* interrupt.
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* The pointer is set up so that an interrupt automatically saves the
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* current process's registers ip:cs:f:sp:ss in the correct slots in the
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* process table.
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*/
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tss.ss0 = DS_SELECTOR;
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init_dataseg(&gdt[TSS_INDEX], vir2phys(&tss), sizeof(tss), INTR_PRIVILEGE);
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gdt[TSS_INDEX].access = PRESENT | (INTR_PRIVILEGE << DPL_SHIFT) | TSS_TYPE;
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/* Build descriptors for interrupt gates in IDT. */
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for (gtp = &gate_table[0];
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gtp < &gate_table[sizeof gate_table / sizeof gate_table[0]]; ++gtp) {
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int_gate(gtp->vec_nr, (vir_bytes) gtp->gate,
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PRESENT | INT_GATE_TYPE | (gtp->privilege << DPL_SHIFT));
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}
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/* Complete building of main TSS. */
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tss.iobase = sizeof tss; /* empty i/o permissions map */
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}
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/*===========================================================================*
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* sdesc *
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*===========================================================================*/
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PRIVATE void sdesc(segdp, base, size)
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register struct segdesc_s *segdp;
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phys_bytes base;
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vir_bytes size;
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{
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/* Fill in the size fields (base, limit and granularity) of a descriptor. */
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segdp->base_low = base;
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segdp->base_middle = base >> BASE_MIDDLE_SHIFT;
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segdp->base_high = base >> BASE_HIGH_SHIFT;
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--size; /* convert to a limit, 0 size means 4G */
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if (size > BYTE_GRAN_MAX) {
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segdp->limit_low = size >> PAGE_GRAN_SHIFT;
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segdp->granularity = GRANULAR | (size >>
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(PAGE_GRAN_SHIFT + GRANULARITY_SHIFT));
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} else {
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segdp->limit_low = size;
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segdp->granularity = size >> GRANULARITY_SHIFT;
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}
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segdp->granularity |= DEFAULT; /* means BIG for data seg */
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}
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/*===========================================================================*
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* int_gate *
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*===========================================================================*/
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PRIVATE void int_gate(vec_nr, offset, dpl_type)
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unsigned vec_nr;
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vir_bytes offset;
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unsigned dpl_type;
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{
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/* Build descriptor for an interrupt gate. */
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register struct gatedesc_s *idp;
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idp = &idt[vec_nr];
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idp->offset_low = offset;
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idp->selector = CS_SELECTOR;
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idp->p_dpl_type = dpl_type;
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idp->offset_high = offset >> OFFSET_HIGH_SHIFT;
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}
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/*===========================================================================*
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* alloc_segments *
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*===========================================================================*/
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PUBLIC void alloc_segments(register struct proc *rp)
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{
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/* This is called at system initialization from main() and by do_newmap().
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* The code has a separate function because of all hardware-dependencies.
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* Note that IDLE is part of the kernel and gets TASK_PRIVILEGE here.
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*/
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phys_bytes code_bytes;
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phys_bytes data_bytes;
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int privilege;
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data_bytes = (phys_bytes) (rp->p_memmap[S].mem_vir +
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rp->p_memmap[S].mem_len) << CLICK_SHIFT;
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if (rp->p_memmap[T].mem_len == 0)
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code_bytes = data_bytes; /* common I&D, poor protect */
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else
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code_bytes = (phys_bytes) rp->p_memmap[T].mem_len << CLICK_SHIFT;
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if( (iskernelp(rp)))
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privilege = TASK_PRIVILEGE;
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else
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privilege = USER_PRIVILEGE;
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init_codeseg(&rp->p_seg.p_ldt[CS_LDT_INDEX],
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(phys_bytes) rp->p_memmap[T].mem_phys << CLICK_SHIFT,
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code_bytes, privilege);
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init_dataseg(&rp->p_seg.p_ldt[DS_LDT_INDEX],
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(phys_bytes) rp->p_memmap[D].mem_phys << CLICK_SHIFT,
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data_bytes, privilege);
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rp->p_reg.cs = (CS_LDT_INDEX * DESC_SIZE) | TI | privilege;
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rp->p_reg.gs =
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rp->p_reg.fs =
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rp->p_reg.ss =
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rp->p_reg.es =
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rp->p_reg.ds = (DS_LDT_INDEX*DESC_SIZE) | TI | privilege;
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}
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