minix/lib/syslib/alloc_util.c

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#include "syslib.h"
#include <stdlib.h>
#include <errno.h>
#include <sys/mman.h>
#include <minix/sysutil.h>
int sys_umap_data_fb(endpoint_t ep, vir_bytes buf, vir_bytes len, phys_bytes *phys)
{
int r;
if((r=sys_umap(ep, VM_D, buf, len, phys)) != OK) {
if(r != EINVAL)
return r;
r = sys_umap(ep, D, buf, len, phys);
}
return r;
}
void *alloc_contig(size_t len, int flags, phys_bytes *phys)
{
int r;
vir_bytes buf;
int mmapflags = MAP_PREALLOC|MAP_CONTIG|MAP_ANON;
if(flags & AC_LOWER16M)
mmapflags |= MAP_LOWER16M;
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if(flags & AC_LOWER1M)
mmapflags |= MAP_LOWER1M;
if(flags & AC_ALIGN64K)
mmapflags |= MAP_ALIGN64K;
/* First try to get memory with mmap. This is gauranteed
* to be page-aligned, and we can tell VM it has to be
* pre-allocated and contiguous.
*/
errno = 0;
buf = (vir_bytes) mmap(0, len, PROT_READ|PROT_WRITE, mmapflags, -1, 0);
/* If that failed, maybe we're not running in paged mode.
* If that's the case, ENXIO will be returned.
* Memory returned with malloc() will be preallocated and
* contiguous, so fallback on that, and ask for a little extra
* so we can page align it ourselves.
*/
if(buf == (vir_bytes) MAP_FAILED) {
u32_t align = 0;
if(errno != (_SIGN ENXIO)) {
return NULL;
}
if(flags & AC_ALIGN4K)
align = 4*1024;
if(flags & AC_ALIGN64K)
align = 64*1024;
if(len + align < len)
return NULL;
len += align;
if(!(buf = (vir_bytes) malloc(len))) {
return NULL;
}
if(align)
buf += align - (buf % align);
}
/* Get physical address, if requested. */
if(phys != NULL && sys_umap_data_fb(SELF, buf, len, phys) != OK)
panic("alloc_contig.c", "sys_umap_data_fb failed", NO_NUM);
return (void *) buf;
}