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/* Project:     OSLib
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 * Description: The OS Construction Kit
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 * Date:                1.6.2000
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 * Idea by:             Luca Abeni & Gerardo Lamastra
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 *
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 * OSLib is an SO project aimed at developing a common, easy-to-use
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 * low-level infrastructure for developing OS kernels and Embedded
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 * Applications; it partially derives from the HARTIK project but it
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 * currently is independently developed.
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 *
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 * OSLib is distributed under GPL License, and some of its code has
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 * been derived from the Linux kernel source; also some important
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 * ideas come from studying the DJGPP go32 extender.
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 *
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 * We acknowledge the Linux Community, Free Software Foundation,
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 * D.J. Delorie and all the other developers who believe in the
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 * freedom of software and ideas.
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 *
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 * For legalese, check out the included GPL license.
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 */
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/*      Routines that implements threads (creation, end, dump, and AS
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        assignment      */
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#include <ll/i386/stdio.h>
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#include <ll/i386/mem.h>
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#include <ll/i386/cons.h>
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#include <ll/i386/error.h>
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#include <ll/i386/tss-ctx.h>
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#include <ll/sys/ll/ll-instr.h>                 /* Only for HW instr... */
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#include <ll/sys/ll/ll-func.h>
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FILE(KL-Context-Switch);
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extern TSS  TSS_table[TSSMax];
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extern WORD TSS_control[TSSMax];
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extern BYTE ll_FPU_stdctx[FPU_CONTEXT_SIZE];
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#ifdef __VIRCSW__
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extern unsigned short int currCtx;
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extern int activeInt;
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#endif
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extern DWORD entrypoint;
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/* Just a debugging function; it dumps the status of the TSS */
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void dump_TSS(WORD sel)
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{
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    BYTE acc,gran;
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    DWORD base,lim;
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    message("TR %x\n", sel);
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    sel = TSSsel2index(sel);
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    message("SS:SP %x:%lx\n", TSS_table[sel].ss, TSS_table[sel].esp);
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    message("Stack0 : %x:%lx\n", TSS_table[sel].ss0, TSS_table[sel].esp0);
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    message("Stack1 : %x:%lx\n", TSS_table[sel].ss1, TSS_table[sel].esp1);
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    message("Stack2 : %x:%lx\n", TSS_table[sel].ss2, TSS_table[sel].esp2);
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    message("CS : %x DS : %x\n", TSS_table[sel].cs, TSS_table[sel].ds);
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    sel = TSSindex2sel(sel);
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    message("Descriptor [%x] Info",sel);
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    base = GDT_read(sel,&lim,&acc,&gran);
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    message("Base : %lx Lim : %lx Acc : %x Gran %x\n", base, lim, (unsigned)(acc),(unsigned)(gran));
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}
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void ll_context_setspace(CONTEXT c, WORD as)
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{
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        int index = TSSsel2index(c);
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    TSS_table[index].ss0 = as;
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    TSS_table[index].cs = as + 8;
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    TSS_table[index].es = as;
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    TSS_table[index].ds = as;
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    TSS_table[index].ss = as;
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}
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/* Initialize context -> TSS in 32 bit */
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CONTEXT ll_context_create(void (*task)(void *p),BYTE *stack,
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                                void *parm,void (*killer)(void),WORD control)
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{
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    CONTEXT index = 0;
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    DWORD *stack_ptr = (DWORD *)stack;
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    /* Push onto stack the input parameter              */
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    /* And the entry point to the task killer procedure */
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    stack_ptr--;
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    *stack_ptr = (DWORD)(parm);
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    stack_ptr--;
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    *stack_ptr = (DWORD)(killer);
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    /* Find a free TSS */
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    while ((TSS_control[index] & TSS_USED) && (index < TSSMain)) index++;
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    /* This exception would signal an error */
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    if (index >= TSSMain) {
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        message("No more Descriptors...\n");
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        return 0;
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    }
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    TSS_control[index] |= (TSS_USED | control);
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    /* Fill the TSS structure */
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    /* No explicit protection; use only one stack */
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    TSS_table[index].esp0 = (DWORD)(stack_ptr);
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    TSS_table[index].esp1 = 0;
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    TSS_table[index].esp2 = 0;
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    TSS_table[index].ss0 = get_DS();
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    TSS_table[index].ss1 = 0;
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    TSS_table[index].ss2 = 0;
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    /* No paging activated */
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    TSS_table[index].cr3 = 0;
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    /* Task entry point */
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    TSS_table[index].eip = (DWORD)(task);
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    /* Need only to unmask interrupts */
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    TSS_table[index].eflags = 0x00000200;
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    TSS_table[index].eax = 0;
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    TSS_table[index].ebx = 0;
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    TSS_table[index].ecx = 0;
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    TSS_table[index].edx = 0;
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    TSS_table[index].esi = 0;
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    TSS_table[index].edi = 0;
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    TSS_table[index].esp = (DWORD)(stack_ptr);
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    TSS_table[index].ebp = (DWORD)(stack_ptr);
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    TSS_table[index].cs = get_CS();
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    TSS_table[index].es = get_DS();
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    TSS_table[index].ds = get_DS();
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    TSS_table[index].ss = get_DS();
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    TSS_table[index].gs = X_FLATDATA_SEL;
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    TSS_table[index].fs = X_FLATDATA_SEL;
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    /* Use only the GDT */
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    TSS_table[index].ldt = 0;
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    TSS_table[index].trap = 0;
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    TSS_table[index].io_base = 0;
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    /* Fill in the coprocessor status */
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    memcpy(TSS_table[index].ctx_FPU,ll_FPU_stdctx,FPU_CONTEXT_SIZE);
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    /* Convert the index into a valid selector  */
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    /* Which really represent CONTEXT           */
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    return(TSSindex2sel(index));
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}
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/* Release the used TSS */
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void ll_context_delete(CONTEXT c)
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{
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    int index = TSSsel2index(c);
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    TSS_control[index] = 0;
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}
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#if 0           /* It does not work... Fix it!!! */
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DWORD ll_push_func(void (*func)(void))
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{
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        DWORD *p;
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        DWORD old;
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        p = (DWORD *)entrypoint;
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        old = *p;
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        *p = (DWORD)func;
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        return old;
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}
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#endif
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/* Well this is used for debug purposes mainly; as the context is an       */
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/* abstract type, we must provide some function to convert in into a       */
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/* printable form; anyway this depend from the architecture as the context */
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char *ll_context_sprintf(char *str, CONTEXT c)
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{
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    ksprintf(str, "%x (Hex)", c);
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    return(str);
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}