| 1 | /* The kernel call implemented in this file:
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| 2 | * m_type: SYS_SEGCTL
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| 3 | *
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| 4 | * The parameters for this kernel call are:
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| 5 | * m4_l3: SEG_PHYS (physical base address)
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| 6 | * m4_l4: SEG_SIZE (size of segment)
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| 7 | * m4_l1: SEG_SELECT (return segment selector here)
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| 8 | * m4_l2: SEG_OFFSET (return offset within segment here)
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| 9 | * m4_l5: SEG_INDEX (return index into remote memory map here)
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| 10 | */
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| 11 | #include "../system.h"
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| 12 | #include "../protect.h"
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| 13 |
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| 14 | #if USE_SEGCTL
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| 15 |
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| 16 | /*===========================================================================*
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| 17 | * do_segctl *
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| 18 | *===========================================================================*/
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| 19 | PUBLIC int do_segctl(m_ptr)
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| 20 | register message *m_ptr; /* pointer to request message */
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| 21 | {
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| 22 | /* Return a segment selector and offset that can be used to reach a physical
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| 23 | * address, for use by a driver doing memory I/O in the A0000 - DFFFF range.
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| 24 | */
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| 25 | u16_t selector;
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| 26 | vir_bytes offset;
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| 27 | int i, index;
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| 28 | register struct proc *rp;
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| 29 | phys_bytes phys = (phys_bytes) m_ptr->SEG_PHYS;
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| 30 | vir_bytes size = (vir_bytes) m_ptr->SEG_SIZE;
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| 31 | int result;
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| 32 |
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| 33 | /* First check if there is a slot available for this segment. */
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| 34 | rp = proc_addr(m_ptr->m_source);
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| 35 | index = -1;
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| 36 | for (i=0; i < NR_REMOTE_SEGS; i++) {
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| 37 | if (! rp->p_priv->s_farmem[i].in_use) {
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| 38 | index = i;
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| 39 | rp->p_priv->s_farmem[i].in_use = TRUE;
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| 40 | rp->p_priv->s_farmem[i].mem_phys = phys;
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| 41 | rp->p_priv->s_farmem[i].mem_len = size;
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| 42 | break;
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| 43 | }
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| 44 | }
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| 45 | if (index < 0) return(ENOSPC);
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| 46 |
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| 47 | if (! machine.protected) {
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| 48 | selector = phys / HCLICK_SIZE;
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| 49 | offset = phys % HCLICK_SIZE;
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| 50 | result = OK;
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| 51 | } else {
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| 52 | /* Check if the segment size can be recorded in bytes, that is, check
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| 53 | * if descriptor's limit field can delimited the allowed memory region
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| 54 | * precisely. This works up to 1MB. If the size is larger, 4K pages
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| 55 | * instead of bytes are used.
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| 56 | */
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| 57 | if (size < BYTE_GRAN_MAX) {
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| 58 | init_dataseg(&rp->p_ldt[EXTRA_LDT_INDEX+i], phys, size,
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| 59 | USER_PRIVILEGE);
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| 60 | selector = ((EXTRA_LDT_INDEX+i)*0x08) | (1*0x04) | USER_PRIVILEGE;
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| 61 | offset = 0;
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| 62 | result = OK;
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| 63 | } else {
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| 64 | init_dataseg(&rp->p_ldt[EXTRA_LDT_INDEX+i], phys & ~0xFFFF, 0,
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| 65 | USER_PRIVILEGE);
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| 66 | selector = ((EXTRA_LDT_INDEX+i)*0x08) | (1*0x04) | USER_PRIVILEGE;
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| 67 | offset = phys & 0xFFFF;
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| 68 | result = OK;
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| 69 | }
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| 70 | }
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| 71 |
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| 72 | /* Request successfully done. Now return the result. */
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| 73 | m_ptr->SEG_INDEX = index | REMOTE_SEG;
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| 74 | m_ptr->SEG_SELECT = selector;
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| 75 | m_ptr->SEG_OFFSET = offset;
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| 76 | return(result);
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| 77 | }
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| 78 |
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| 79 | #endif /* USE_SEGCTL */
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| 80 |
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