cca24d06d8
kernel (sys task). The main reason is that these would have to become cpu local variables on SMP. Once the system task is not a task but a genuine part of the kernel there is even less reason to have these extra variables as proc_ptr will already contain all neccessary information. In addition converting who_e to the process pointer and back again all the time will be avoided. Although proc_ptr will contain all important information, accessing it as a cpu local variable will be fairly expensive, hence the value would be assigned to some on stack local variable. Therefore it is better to add the 'caller' argument to the syscall handlers to pass the value on stack anyway. It also clearly denotes on who's behalf is the syscall being executed. This patch also ANSIfies the syscall function headers. Last but not least, it also fixes a potential bug in virtual_copy_f() in case the check is disabled. So far the function in case of a failure could possible reuse an old who_p in case this function had not been called from the system task. virtual_copy_f() takes the caller as a parameter too. In case the checking is disabled, the caller must be NULL and non NULL if it is enabled as we must be able to suspend the caller.
55 lines
1.7 KiB
C
55 lines
1.7 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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#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(struct proc * caller, message * m_ptr)
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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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u32_t selector;
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vir_bytes offset;
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int i, index;
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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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index = -1;
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for (i=0; i < NR_REMOTE_SEGS; i++) {
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if (! caller->p_priv->s_farmem[i].in_use) {
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index = i;
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caller->p_priv->s_farmem[i].in_use = TRUE;
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caller->p_priv->s_farmem[i].mem_phys = phys;
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caller->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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offset = alloc_remote_segment(&selector, &caller->p_seg,
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i, phys, size, USER_PRIVILEGE);
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result = OK;
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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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