/* This file contains code for initialization of protected mode, to initialize * code and data segment descriptors, and to initialize global descriptors * for local descriptors in the process table. */ #include "kernel.h" #include "proc.h" #include "protect.h" #if _WORD_SIZE == 4 #define INT_GATE_TYPE (INT_286_GATE | DESC_386_BIT) #define TSS_TYPE (AVL_286_TSS | DESC_386_BIT) #else #define INT_GATE_TYPE INT_286_GATE #define TSS_TYPE AVL_286_TSS #endif struct desctableptr_s { char limit[sizeof(u16_t)]; char base[sizeof(u32_t)]; /* really u24_t + pad for 286 */ }; struct gatedesc_s { u16_t offset_low; u16_t selector; u8_t pad; /* |000|XXXXX| ig & trpg, |XXXXXXXX| task g */ u8_t p_dpl_type; /* |P|DL|0|TYPE| */ #if _WORD_SIZE == 4 u16_t offset_high; #else u16_t reserved; #endif }; struct tss_s { reg_t backlink; reg_t sp0; /* stack pointer to use during interrupt */ reg_t ss0; /* " segment " " " " */ reg_t sp1; reg_t ss1; reg_t sp2; reg_t ss2; #if _WORD_SIZE == 4 reg_t cr3; #endif reg_t ip; reg_t flags; reg_t ax; reg_t cx; reg_t dx; reg_t bx; reg_t sp; reg_t bp; reg_t si; reg_t di; reg_t es; reg_t cs; reg_t ss; reg_t ds; #if _WORD_SIZE == 4 reg_t fs; reg_t gs; #endif reg_t ldt; #if _WORD_SIZE == 4 u16_t trap; u16_t iobase; /* u8_t iomap[0]; */ #endif }; PUBLIC struct segdesc_s gdt[GDT_SIZE]; PRIVATE struct gatedesc_s idt[IDT_SIZE]; /* zero-init so none present */ PUBLIC struct tss_s tss; /* zero init */ FORWARD _PROTOTYPE( void int_gate, (unsigned vec_nr, phys_bytes base, unsigned dpl_type) ); FORWARD _PROTOTYPE( void sdesc, (struct segdesc_s *segdp, phys_bytes base, phys_bytes size) ); /*=========================================================================* * prot_init * *=========================================================================*/ PUBLIC void prot_init() { /* Set up tables for protected mode. * All GDT slots are allocated at compile time. */ phys_bytes code_bytes; phys_bytes data_bytes; struct gate_table_s *gtp; struct desctableptr_s *dtp; unsigned ldt_selector; register struct proc *rp; static struct gate_table_s { _PROTOTYPE( void (*gate), (void) ); unsigned char vec_nr; unsigned char privilege; } gate_table[] = { divide_error, DIVIDE_VECTOR, INTR_PRIVILEGE, single_step_exception, DEBUG_VECTOR, INTR_PRIVILEGE, nmi, NMI_VECTOR, INTR_PRIVILEGE, breakpoint_exception, BREAKPOINT_VECTOR, USER_PRIVILEGE, overflow, OVERFLOW_VECTOR, USER_PRIVILEGE, bounds_check, BOUNDS_VECTOR, INTR_PRIVILEGE, inval_opcode, INVAL_OP_VECTOR, INTR_PRIVILEGE, copr_not_available, COPROC_NOT_VECTOR, INTR_PRIVILEGE, double_fault, DOUBLE_FAULT_VECTOR, INTR_PRIVILEGE, copr_seg_overrun, COPROC_SEG_VECTOR, INTR_PRIVILEGE, inval_tss, INVAL_TSS_VECTOR, INTR_PRIVILEGE, segment_not_present, SEG_NOT_VECTOR, INTR_PRIVILEGE, stack_exception, STACK_FAULT_VECTOR, INTR_PRIVILEGE, general_protection, PROTECTION_VECTOR, INTR_PRIVILEGE, #if _WORD_SIZE == 4 page_fault, PAGE_FAULT_VECTOR, INTR_PRIVILEGE, copr_error, COPROC_ERR_VECTOR, INTR_PRIVILEGE, #endif { hwint00, VECTOR( 0), INTR_PRIVILEGE }, { hwint01, VECTOR( 1), INTR_PRIVILEGE }, { hwint02, VECTOR( 2), INTR_PRIVILEGE }, { hwint03, VECTOR( 3), INTR_PRIVILEGE }, { hwint04, VECTOR( 4), INTR_PRIVILEGE }, { hwint05, VECTOR( 5), INTR_PRIVILEGE }, { hwint06, VECTOR( 6), INTR_PRIVILEGE }, { hwint07, VECTOR( 7), INTR_PRIVILEGE }, { hwint08, VECTOR( 8), INTR_PRIVILEGE }, { hwint09, VECTOR( 9), INTR_PRIVILEGE }, { hwint10, VECTOR(10), INTR_PRIVILEGE }, { hwint11, VECTOR(11), INTR_PRIVILEGE }, { hwint12, VECTOR(12), INTR_PRIVILEGE }, { hwint13, VECTOR(13), INTR_PRIVILEGE }, { hwint14, VECTOR(14), INTR_PRIVILEGE }, { hwint15, VECTOR(15), INTR_PRIVILEGE }, }; /* This is called early and can't use tables set up by main(). */ data_bytes = (phys_bytes) sizes[1] << CLICK_SHIFT; if (sizes[0] == 0) code_bytes = data_bytes; /* common I&D */ else code_bytes = (phys_bytes) sizes[0] << CLICK_SHIFT; /* Build gdt and idt pointers in GDT where the BIOS expects them. */ dtp= (struct desctableptr_s *) &gdt[GDT_INDEX]; * (u16_t *) dtp->limit = (sizeof gdt) - 1; * (u32_t *) dtp->base = vir2phys(gdt); dtp= (struct desctableptr_s *) &gdt[IDT_INDEX]; * (u16_t *) dtp->limit = (sizeof idt) - 1; * (u32_t *) dtp->base = vir2phys(idt); /* Build segment descriptors for tasks and interrupt handlers. */ init_codeseg(&gdt[CS_INDEX], code_base, code_bytes, INTR_PRIVILEGE); init_dataseg(&gdt[DS_INDEX], data_base, data_bytes, INTR_PRIVILEGE); init_dataseg(&gdt[ES_INDEX], 0L, 0L, TASK_PRIVILEGE); /* Build scratch descriptors for functions in klib88. */ init_dataseg(&gdt[DS_286_INDEX], (phys_bytes) 0, (phys_bytes) MAX_286_SEG_SIZE, TASK_PRIVILEGE); init_dataseg(&gdt[ES_286_INDEX], (phys_bytes) 0, (phys_bytes) MAX_286_SEG_SIZE, TASK_PRIVILEGE); /* Build local descriptors in GDT for LDT's in process table. * The LDT's are allocated at compile time in the process table, and * initialized whenever a process' map is initialized or changed. */ for (rp = BEG_PROC_ADDR, ldt_selector = FIRST_LDT_INDEX * DESC_SIZE; rp < END_PROC_ADDR; ++rp, ldt_selector += DESC_SIZE) { init_dataseg(&gdt[ldt_selector / DESC_SIZE], vir2phys(rp->p_ldt), (phys_bytes) sizeof rp->p_ldt, INTR_PRIVILEGE); gdt[ldt_selector / DESC_SIZE].access = PRESENT | LDT; rp->p_ldt_sel = ldt_selector; } /* Build main TSS. * This is used only to record the stack pointer to be used after an * interrupt. * The pointer is set up so that an interrupt automatically saves the * current process's registers ip:cs:f:sp:ss in the correct slots in the * process table. */ tss.ss0 = DS_SELECTOR; init_dataseg(&gdt[TSS_INDEX], vir2phys(&tss), (phys_bytes) sizeof tss, INTR_PRIVILEGE); gdt[TSS_INDEX].access = PRESENT | (INTR_PRIVILEGE << DPL_SHIFT) | TSS_TYPE; /* Build descriptors for interrupt gates in IDT. */ for (gtp = &gate_table[0]; gtp < &gate_table[sizeof gate_table / sizeof gate_table[0]]; ++gtp) { int_gate(gtp->vec_nr, (phys_bytes) (vir_bytes) gtp->gate, PRESENT | INT_GATE_TYPE | (gtp->privilege << DPL_SHIFT)); } int_gate(SYS_VECTOR, (phys_bytes) (vir_bytes) p_s_call, PRESENT | (USER_PRIVILEGE << DPL_SHIFT) | INT_GATE_TYPE); int_gate(LEVEL0_VECTOR, (phys_bytes) (vir_bytes) level0_call, PRESENT | (TASK_PRIVILEGE << DPL_SHIFT) | INT_GATE_TYPE); #if _WORD_SIZE == 4 /* Complete building of main TSS. */ tss.iobase = sizeof tss; /* empty i/o permissions map */ /* Complete building of interrupt gates. */ int_gate(SYS386_VECTOR, (phys_bytes) (vir_bytes) s_call, PRESENT | (USER_PRIVILEGE << DPL_SHIFT) | INT_GATE_TYPE); #endif } /*=========================================================================* * init_codeseg * *=========================================================================*/ PUBLIC void init_codeseg(segdp, base, size, privilege) register struct segdesc_s *segdp; phys_bytes base; phys_bytes size; int privilege; { /* Build descriptor for a code segment. */ sdesc(segdp, base, size); segdp->access = (privilege << DPL_SHIFT) | (PRESENT | SEGMENT | EXECUTABLE | READABLE); /* CONFORMING = 0, ACCESSED = 0 */ } /*=========================================================================* * init_dataseg * *=========================================================================*/ PUBLIC void init_dataseg(segdp, base, size, privilege) register struct segdesc_s *segdp; phys_bytes base; phys_bytes size; int privilege; { /* Build descriptor for a data segment. */ sdesc(segdp, base, size); segdp->access = (privilege << DPL_SHIFT) | (PRESENT | SEGMENT | WRITEABLE); /* EXECUTABLE = 0, EXPAND_DOWN = 0, ACCESSED = 0 */ } /*=========================================================================* * sdesc * *=========================================================================*/ PRIVATE void sdesc(segdp, base, size) register struct segdesc_s *segdp; phys_bytes base; phys_bytes size; { /* Fill in the size fields (base, limit and granularity) of a descriptor. */ segdp->base_low = base; segdp->base_middle = base >> BASE_MIDDLE_SHIFT; #if _WORD_SIZE == 4 segdp->base_high = base >> BASE_HIGH_SHIFT; --size; /* convert to a limit, 0 size means 4G */ if (size > BYTE_GRAN_MAX) { segdp->limit_low = size >> PAGE_GRAN_SHIFT; segdp->granularity = GRANULAR | (size >> (PAGE_GRAN_SHIFT + GRANULARITY_SHIFT)); } else { segdp->limit_low = size; segdp->granularity = size >> GRANULARITY_SHIFT; } segdp->granularity |= DEFAULT; /* means BIG for data seg */ #else segdp->limit_low = size - 1; #endif } /*=========================================================================* * seg2phys * *=========================================================================*/ PUBLIC phys_bytes seg2phys(seg) U16_t seg; { /* Return the base address of a segment, with seg being either a 8086 segment * register, or a 286/386 segment selector. */ phys_bytes base; struct segdesc_s *segdp; if (!protected_mode) { base = hclick_to_physb(seg); } else { segdp = &gdt[seg >> 3]; base = segdp->base_low | ((u32_t) segdp->base_middle << 16); #if _WORD_SIZE == 4 base |= ((u32_t) segdp->base_high << 24); #endif } return base; } /*=========================================================================* * int_gate * *=========================================================================*/ PRIVATE void int_gate(vec_nr, base, dpl_type) unsigned vec_nr; phys_bytes base; unsigned dpl_type; { /* Build descriptor for an interrupt gate. */ register struct gatedesc_s *idp; idp = &idt[vec_nr]; idp->offset_low = base; idp->selector = CS_SELECTOR; idp->p_dpl_type = dpl_type; #if _WORD_SIZE == 4 idp->offset_high = base >> OFFSET_HIGH_SHIFT; #endif } /*=========================================================================* * enable_iop * *=========================================================================*/ PUBLIC void enable_iop(pp) struct proc *pp; { /* Allow a user process to use I/O instructions. Change the I/O Permission * Level bits in the psw. These specify least-privileged Current Permission * Level allowed to execute I/O instructions. Users and servers have CPL 3. * You can't have less privilege than that. Kernel has CPL 0, tasks CPL 1. */ pp->p_reg.psw |= 0x3000; }