49eb1f4806
Primary purpose of change: to support the mmap implementation, VM must know both (a) about some block metadata for FS cache blocks, i.e. inode numbers and inode offsets where applicable; and (b) know about *all* cache blocks, i.e. also of the FS primary caches and not just the blocks that spill into the secondary one. This changes the interface and VM data structures. This change is only for the interface (libminixfs) and VM data structures; the filesystem code is unmodified, so although the secondary cache will be used as normal, blocks will not be annotated with inode information until the FS is modified to provide this information. Until it is modified, mmap of files will fail gracefully on such filesystems. This is indicated to VFS/VM by returning ENOSYS for REQ_PEEK. Change-Id: I1d2df6c485e6c5e89eb28d9055076cc02629594e
139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
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/* This file implements the methods of anonymous memory.
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*
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* Anonymous memory is memory that is for private use to a process
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* and can not be related to a file (hence anonymous).
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*/
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#include <assert.h>
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#include "proto.h"
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#include "vm.h"
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#include "region.h"
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#include "glo.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 void anon_split(struct vmproc *vmp, struct vir_region *vr,
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struct vir_region *r1, struct vir_region *r2);
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static int anon_lowshrink(struct vir_region *vr, vir_bytes len);
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static int anon_unreference(struct phys_region *pr);
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static int anon_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write, vfs_callback_t cb, void *, int);
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static int anon_sanitycheck(struct phys_region *pr, char *file, int line);
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static int anon_writable(struct phys_region *pr);
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static int anon_resize(struct vmproc *vmp, struct vir_region *vr, vir_bytes l);
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static u32_t anon_regionid(struct vir_region *region);
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static int anon_refcount(struct vir_region *vr);
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struct mem_type mem_type_anon = {
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.name = "anonymous memory",
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.ev_unreference = anon_unreference,
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.ev_pagefault = anon_pagefault,
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.ev_resize = anon_resize,
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.ev_sanitycheck = anon_sanitycheck,
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.ev_lowshrink = anon_lowshrink,
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.ev_split = anon_split,
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.regionid = anon_regionid,
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.writable = anon_writable,
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.refcount = anon_refcount
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};
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static int anon_unreference(struct phys_region *pr)
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{
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assert(pr->ph->refcount == 0);
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if(pr->ph->phys != MAP_NONE)
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free_mem(ABS2CLICK(pr->ph->phys), 1);
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return OK;
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}
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static int anon_pagefault(struct vmproc *vmp, struct vir_region *region,
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struct phys_region *ph, int write, vfs_callback_t cb, void *st, int l)
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{
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phys_bytes new_page, new_page_cl;
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u32_t allocflags;
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allocflags = vrallocflags(region->flags);
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assert(ph->ph->refcount > 0);
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if((new_page_cl = alloc_mem(1, allocflags)) == NO_MEM)
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return ENOMEM;
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new_page = CLICK2ABS(new_page_cl);
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/* Totally new block? Create it. */
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if(ph->ph->phys == MAP_NONE) {
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ph->ph->phys = new_page;
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assert(ph->ph->phys != MAP_NONE);
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return OK;
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}
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if(ph->ph->refcount < 2 || !write) {
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printf("anon_pagefault: %d refcount, %d write - not handling pagefault\n",
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ph->ph->refcount, write);
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return OK;
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}
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assert(region->flags & VR_WRITABLE);
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return mem_cow(region, ph, new_page_cl, new_page);
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}
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static int anon_sanitycheck(struct phys_region *pr, char *file, int line)
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{
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MYASSERT(usedpages_add(pr->ph->phys, VM_PAGE_SIZE) == OK);
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return OK;
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}
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static int anon_writable(struct phys_region *pr)
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{
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assert(pr->ph->refcount > 0);
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if(pr->ph->phys == MAP_NONE)
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return 0;
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if(pr->parent->remaps > 0)
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return 1;
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return pr->ph->refcount == 1;
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}
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static int anon_resize(struct vmproc *vmp, struct vir_region *vr, vir_bytes l)
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{
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/* Shrinking not implemented; silently ignored.
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* (Which is ok for brk().)
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*/
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if(l <= vr->length)
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return OK;
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assert(vr);
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assert(vr->flags & VR_ANON);
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assert(!(l % VM_PAGE_SIZE));
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USE(vr, vr->length = l;);
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return OK;
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}
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static u32_t anon_regionid(struct vir_region *region)
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{
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return region->id;
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}
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static int anon_lowshrink(struct vir_region *vr, vir_bytes len)
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{
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return OK;
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}
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static int anon_refcount(struct vir_region *vr)
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{
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return 1 + vr->remaps;
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}
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static void anon_split(struct vmproc *vmp, struct vir_region *vr,
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struct vir_region *r1, struct vir_region *r2)
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{
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return;
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}
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