81 lines
2.6 KiB
C
81 lines
2.6 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_SEGCTL
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*
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* The parameters for this kernel call are:
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* m4_l3: SEG_PHYS (physical base address)
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* m4_l4: SEG_SIZE (size of segment)
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* m4_l1: SEG_SELECT (return segment selector here)
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* m4_l2: SEG_OFFSET (return offset within segment here)
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* m4_l5: SEG_INDEX (return index into remote memory map here)
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*/
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#include "../system.h"
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#include "../protect.h"
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#if USE_SEGCTL
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/*===========================================================================*
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* do_segctl *
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*===========================================================================*/
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PUBLIC int do_segctl(m_ptr)
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register message *m_ptr; /* pointer to request message */
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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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u16_t selector;
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vir_bytes offset;
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int i, index;
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register struct proc *rp;
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phys_bytes phys = (phys_bytes) m_ptr->SEG_PHYS;
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vir_bytes size = (vir_bytes) m_ptr->SEG_SIZE;
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int result;
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/* First check if there is a slot available for this segment. */
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rp = proc_addr(m_ptr->m_source);
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index = -1;
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for (i=0; i < NR_REMOTE_SEGS; i++) {
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if (! rp->p_priv->s_farmem[i].in_use) {
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index = i;
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rp->p_priv->s_farmem[i].in_use = TRUE;
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rp->p_priv->s_farmem[i].mem_phys = phys;
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rp->p_priv->s_farmem[i].mem_len = size;
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break;
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}
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}
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if (index < 0) return(ENOSPC);
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if (! machine.protected) {
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selector = phys / HCLICK_SIZE;
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offset = phys % HCLICK_SIZE;
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result = OK;
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} else {
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/* Check if the segment size can be recorded in bytes, that is, check
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* if descriptor's limit field can delimited the allowed memory region
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* precisely. This works up to 1MB. If the size is larger, 4K pages
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* instead of bytes are used.
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*/
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if (size < BYTE_GRAN_MAX) {
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init_dataseg(&rp->p_ldt[EXTRA_LDT_INDEX+i], phys, size,
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USER_PRIVILEGE);
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selector = ((EXTRA_LDT_INDEX+i)*0x08) | (1*0x04) | USER_PRIVILEGE;
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offset = 0;
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result = OK;
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} else {
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init_dataseg(&rp->p_ldt[EXTRA_LDT_INDEX+i], phys & ~0xFFFF, 0,
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USER_PRIVILEGE);
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selector = ((EXTRA_LDT_INDEX+i)*0x08) | (1*0x04) | USER_PRIVILEGE;
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offset = phys & 0xFFFF;
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result = OK;
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}
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}
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/* Request successfully done. Now return the result. */
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m_ptr->SEG_INDEX = index | REMOTE_SEG;
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m_ptr->SEG_SELECT = selector;
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m_ptr->SEG_OFFSET = offset;
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return(result);
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}
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#endif /* USE_SEGCTL */
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