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phunix/kernel/arch/i386/protect.c
Ben Gras 6f77685609 Split of architecture-dependent and -independent functions for i386, 
mainly in the kernel and headers. This split based on work by
Ingmar Alting <iaalting@cs.vu.nl> done for his Minix PowerPC architecture
port.

 . kernel does not program the interrupt controller directly, do any
   other architecture-dependent operations, or contain assembly any more,
   but uses architecture-dependent functions in arch/$(ARCH)/.
 . architecture-dependent constants and types defined in arch/$(ARCH)/include.
 . <ibm/portio.h> moved to <minix/portio.h>, as they have become, for now,
   architecture-independent functions.
 . int86, sdevio, readbios, and iopenable are now i386-specific kernel calls
   and live in arch/i386/do_* now.
 . i386 arch now supports even less 86 code; e.g. mpx86.s and klib86.s have
   gone, and 'machine.protected' is gone (and always taken to be 1 in i386).
   If 86 support is to return, it should be a new architecture.
 . prototypes for the architecture-dependent functions defined in
   kernel/arch/$(ARCH)/*.c but used in kernel/ are in kernel/proto.h
 . /etc/make.conf included in makefiles and shell scripts that need to
   know the building architecture; it defines ARCH=<arch>, currently only
   i386.
 . some basic per-architecture build support outside of the kernel (lib)
 . in clock.c, only dequeue a process if it was ready
 . fixes for new include files

files deleted:
 . mpx/klib.s - only for choosing between mpx/klib86 and -386
 . klib86.s - only for 86

i386-specific files files moved (or arch-dependent stuff moved) to arch/i386/:
 . mpx386.s (entry point)
 . klib386.s
 . sconst.h
 . exception.c
 . protect.c
 . protect.h
 . i8269.c
2006-12-22 15:22:27 +00:00

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/* 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 <archconst.h>
#include "proto.h"
#define INT_GATE_TYPE (INT_286_GATE | DESC_386_BIT)
#define TSS_TYPE (AVL_286_TSS | DESC_386_BIT)
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| */
u16_t offset_high;
};
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;
reg_t cr3;
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;
reg_t fs;
reg_t gs;
reg_t ldt;
u16_t trap;
u16_t iobase;
/* u8_t iomap[0]; */
};
PUBLIC struct segdesc_s gdt[GDT_SIZE]; /* used in klib.s and mpx.s */
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, vir_bytes offset,
unsigned dpl_type) );
FORWARD _PROTOTYPE( void sdesc, (struct segdesc_s *segdp, phys_bytes base,
vir_bytes size) );
/*===========================================================================*
* enable_iop *
*===========================================================================*/
PUBLIC void enable_iop(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;
}
/*===========================================================================*
* seg2phys *
*===========================================================================*/
PUBLIC phys_bytes seg2phys(U16_t seg)
{
/* Return the base address of a segment, with seg being a
* register, or a 286/386 segment selector.
*/
phys_bytes base;
struct segdesc_s *segdp;
segdp = &gdt[seg >> 3];
base = ((u32_t) segdp->base_low << 0)
| ((u32_t) segdp->base_middle << 16)
| ((u32_t) segdp->base_high << 24);
return base;
}
/*===========================================================================*
* phys2seg *
*===========================================================================*/
PUBLIC void phys2seg(u16_t *seg, vir_bytes *off, phys_bytes phys)
{
/* Return a segment selector and offset that can be used to reach a physical
* address, for use by a driver doing memory I/O in the A0000 - DFFFF range.
*/
*seg = FLAT_DS_SELECTOR;
*off = phys;
}
/*===========================================================================*
* init_dataseg *
*===========================================================================*/
PUBLIC void init_dataseg(register struct segdesc_s *segdp,
phys_bytes base, vir_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 */
}
/*===========================================================================*
* init_codeseg *
*===========================================================================*/
PUBLIC void init_codeseg(register struct segdesc_s *segdp, phys_bytes base,
vir_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 */
}
/*===========================================================================*
* prot_init *
*===========================================================================*/
PUBLIC void prot_init(void)
{
/* Set up tables for protected mode.
* All GDT slots are allocated at compile time.
*/
struct gate_table_s *gtp;
struct desctableptr_s *dtp;
unsigned ldt_index;
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 },
{ page_fault, PAGE_FAULT_VECTOR, INTR_PRIVILEGE },
{ copr_error, COPROC_ERR_VECTOR, INTR_PRIVILEGE },
{ 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 },
{ s_call, SYS386_VECTOR, USER_PRIVILEGE }, /* 386 system call */
{ level0_call, LEVEL0_VECTOR, TASK_PRIVILEGE },
};
/* 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],
kinfo.code_base, kinfo.code_size, INTR_PRIVILEGE);
init_dataseg(&gdt[DS_INDEX],
kinfo.data_base, kinfo.data_size, INTR_PRIVILEGE);
init_dataseg(&gdt[ES_INDEX], 0L, 0, TASK_PRIVILEGE);
/* Build scratch descriptors for functions in klib88. */
init_dataseg(&gdt[DS_286_INDEX], 0L, 0, TASK_PRIVILEGE);
init_dataseg(&gdt[ES_286_INDEX], 0L, 0, 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_index = FIRST_LDT_INDEX;
rp < END_PROC_ADDR; ++rp, ldt_index++) {
init_dataseg(&gdt[ldt_index], vir2phys(rp->p_seg.p_ldt),
sizeof(rp->p_seg.p_ldt), INTR_PRIVILEGE);
gdt[ldt_index].access = PRESENT | LDT;
rp->p_seg.p_ldt_sel = ldt_index * DESC_SIZE;
}
/* 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), 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, (vir_bytes) gtp->gate,
PRESENT | INT_GATE_TYPE | (gtp->privilege << DPL_SHIFT));
}
/* Complete building of main TSS. */
tss.iobase = sizeof tss; /* empty i/o permissions map */
}
/*===========================================================================*
* sdesc *
*===========================================================================*/
PRIVATE void sdesc(segdp, base, size)
register struct segdesc_s *segdp;
phys_bytes base;
vir_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;
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 */
}
/*===========================================================================*
* int_gate *
*===========================================================================*/
PRIVATE void int_gate(vec_nr, offset, dpl_type)
unsigned vec_nr;
vir_bytes offset;
unsigned dpl_type;
{
/* Build descriptor for an interrupt gate. */
register struct gatedesc_s *idp;
idp = &idt[vec_nr];
idp->offset_low = offset;
idp->selector = CS_SELECTOR;
idp->p_dpl_type = dpl_type;
idp->offset_high = offset >> OFFSET_HIGH_SHIFT;
}
/*===========================================================================*
* alloc_segments *
*===========================================================================*/
PUBLIC void alloc_segments(register struct proc *rp)
{
/* This is called at system initialization from main() and by do_newmap().
* The code has a separate function because of all hardware-dependencies.
* Note that IDLE is part of the kernel and gets TASK_PRIVILEGE here.
*/
phys_bytes code_bytes;
phys_bytes data_bytes;
int privilege;
data_bytes = (phys_bytes) (rp->p_memmap[S].mem_vir +
rp->p_memmap[S].mem_len) << CLICK_SHIFT;
if (rp->p_memmap[T].mem_len == 0)
code_bytes = data_bytes; /* common I&D, poor protect */
else
code_bytes = (phys_bytes) rp->p_memmap[T].mem_len << CLICK_SHIFT;
privilege = (iskernelp(rp)) ? TASK_PRIVILEGE : USER_PRIVILEGE;
init_codeseg(&rp->p_seg.p_ldt[CS_LDT_INDEX],
(phys_bytes) rp->p_memmap[T].mem_phys << CLICK_SHIFT,
code_bytes, privilege);
init_dataseg(&rp->p_seg.p_ldt[DS_LDT_INDEX],
(phys_bytes) rp->p_memmap[D].mem_phys << CLICK_SHIFT,
data_bytes, privilege);
rp->p_reg.cs = (CS_LDT_INDEX * DESC_SIZE) | TI | privilege;
rp->p_reg.gs =
rp->p_reg.fs =
rp->p_reg.ss =
rp->p_reg.es =
rp->p_reg.ds = (DS_LDT_INDEX*DESC_SIZE) | TI | privilege;
}
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