67 lines
1.8 KiB
C
67 lines
1.8 KiB
C
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/* This file implements the methods of direct physical mapping.
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*
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* A direct physical mapping is done by accepting the physical
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* memory address and range from the caller and allowing direct
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* access to it. Most significantly, no physical memory is allocated
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* when it's mapped or freed when it's unmapped. E.g. device memory.
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*/
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#include "vm.h"
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#include "proto.h"
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/* These functions are static so as to not pollute the
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* global namespace, and are accessed through their function
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* pointers.
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*/
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static int phys_unreference(struct phys_region *pr);
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static int phys_writable(struct phys_region *pr);
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static int phys_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write, vfs_callback_t cb, void *state,
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int len, int *io);
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static int phys_copy(struct vir_region *vr, struct vir_region *newvr);
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struct mem_type mem_type_directphys = {
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.name = "physical memory mapping",
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.ev_copy = phys_copy,
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.ev_unreference = phys_unreference,
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.writable = phys_writable,
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.ev_pagefault = phys_pagefault
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};
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static int phys_unreference(struct phys_region *pr)
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{
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return OK;
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}
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static int phys_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write, vfs_callback_t cb, void *state,
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int len, int *io)
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{
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phys_bytes arg = region->param.phys, phmem;
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assert(arg != MAP_NONE);
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assert(ph->ph->phys == MAP_NONE);
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phmem = arg + ph->offset;
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assert(phmem != MAP_NONE);
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ph->ph->phys = phmem;
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return OK;
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}
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static int phys_writable(struct phys_region *pr)
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{
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assert(pr->ph->refcount > 0);
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return pr->ph->phys != MAP_NONE;
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}
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void phys_setphys(struct vir_region *vr, phys_bytes phys)
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{
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vr->param.phys = phys;
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}
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static int phys_copy(struct vir_region *vr, struct vir_region *newvr)
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{
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newvr->param.phys = vr->param.phys;
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return OK;
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}
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