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minix/drivers/memory/memory.c

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/* This file contains the device dependent part of the drivers for the
* following special files:
* /dev/ram - RAM disk
* /dev/mem - absolute memory
* /dev/kmem - kernel virtual memory
* /dev/null - null device (data sink)
* /dev/boot - boot device loaded from boot image
* /dev/random - random number generator
* /dev/zero - null byte stream generator
*
* Changes:
* Apr 29, 2005 added null byte generator (Jorrit N. Herder)
* Apr 27, 2005 added random device handling (Jorrit N. Herder)
* Apr 09, 2005 added support for boot device (Jorrit N. Herder)
* Jul 26, 2004 moved RAM driver to user-space (Jorrit N. Herder)
* Apr 20, 1992 device dependent/independent split (Kees J. Bot)
*/
#include "../drivers.h"
#include "../libdriver/driver.h"
#include <sys/ioc_memory.h>
#include "../../kernel/const.h"
#include "../../kernel/config.h"
#include "../../kernel/type.h"
#include "assert.h"
#include "random.h"
#define NR_DEVS 7 /* number of minor devices */
#define KRANDOM_PERIOD 1 /* ticks between krandom calls */
PRIVATE struct device m_geom[NR_DEVS]; /* base and size of each device */
PRIVATE int m_seg[NR_DEVS]; /* segment index of each device */
PRIVATE int m_device; /* current device */
PRIVATE struct kinfo kinfo; /* kernel information */
PRIVATE struct machine machine; /* machine information */
PRIVATE struct randomness krandom; /* randomness from the kernel */
extern int errno; /* error number for PM calls */
FORWARD _PROTOTYPE( char *m_name, (void) );
FORWARD _PROTOTYPE( struct device *m_prepare, (int device) );
FORWARD _PROTOTYPE( int m_transfer, (int proc_nr, int opcode, off_t position,
iovec_t *iov, unsigned nr_req) );
FORWARD _PROTOTYPE( int m_do_open, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( void m_init, (void) );
FORWARD _PROTOTYPE( int m_ioctl, (struct driver *dp, message *m_ptr) );
FORWARD _PROTOTYPE( void m_geometry, (struct partition *entry) );
FORWARD _PROTOTYPE( void m_random, (struct driver *dp, message *m_ptr) );
/* Entry points to this driver. */
PRIVATE struct driver m_dtab = {
m_name, /* current device's name */
m_do_open, /* open or mount */
do_nop, /* nothing on a close */
m_ioctl, /* specify ram disk geometry */
m_prepare, /* prepare for I/O on a given minor device */
m_transfer, /* do the I/O */
nop_cleanup, /* no need to clean up */
m_geometry, /* memory device "geometry" */
nop_signal, /* system signals */
m_random, /* get randomness from kernel (alarm) */
nop_cancel,
nop_select,
NULL
};
/* Buffer for the /dev/zero null byte feed. */
#define ZERO_BUF_SIZE 1024
PRIVATE char dev_zero[ZERO_BUF_SIZE];
/* Buffer for the /dev/random number generator. */
#define RANDOM_BUF_SIZE 1024
PRIVATE char random_buf[RANDOM_BUF_SIZE];
#define click_to_round_k(n) \
((unsigned) ((((unsigned long) (n) << CLICK_SHIFT) + 512) / 1024))
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC void main(void)
{
m_init(); /* initialize the memory driver */
driver_task(&m_dtab); /* start driver's main loop */
}
/*===========================================================================*
* m_name *
*===========================================================================*/
PRIVATE char *m_name()
{
/* Return a name for the current device. */
static char name[] = "memory";
return name;
}
/*===========================================================================*
* m_prepare *
*===========================================================================*/
PRIVATE struct device *m_prepare(device)
int device;
{
/* Prepare for I/O on a device: check if the minor device number is ok. */
if (device < 0 || device >= NR_DEVS) return(NIL_DEV);
m_device = device;
return(&m_geom[device]);
}
/*===========================================================================*
* m_transfer *
*===========================================================================*/
PRIVATE int m_transfer(proc_nr, opcode, position, iov, nr_req)
int proc_nr; /* process doing the request */
int opcode; /* DEV_GATHER or DEV_SCATTER */
off_t position; /* offset on device to read or write */
iovec_t *iov; /* pointer to read or write request vector */
unsigned nr_req; /* length of request vector */
{
/* Read or write one the driver's minor devices. */
phys_bytes mem_phys, user_phys;
int seg;
unsigned count, left, chunk;
vir_bytes user_vir;
struct device *dv;
unsigned long dv_size;
int s;
/* Get minor device number and check for /dev/null. */
dv = &m_geom[m_device];
dv_size = cv64ul(dv->dv_size);
while (nr_req > 0) {
/* How much to transfer and where to / from. */
count = iov->iov_size;
user_vir = iov->iov_addr;
switch (m_device) {
/* No copying; ignore request. */
case NULL_DEV:
if (opcode == DEV_GATHER) return(OK); /* always at EOF */
break;
/* Virtual copying. For boot device. */
case RAM_DEV:
case KMEM_DEV:
case BOOT_DEV:
if (position >= dv_size) return(OK); /* check for EOF */
if (position + count > dv_size) count = dv_size - position;
seg = m_seg[m_device];
if (opcode == DEV_GATHER) { /* copy actual data */
sys_vircopy(SELF,seg,position, proc_nr,D,user_vir, count);
} else {
sys_vircopy(proc_nr,D,user_vir, SELF,seg,position, count);
}
break;
/* Physical copying. Only used to access entire memory. */
case MEM_DEV:
if (position >= dv_size) return(OK); /* check for EOF */
if (position + count > dv_size) count = dv_size - position;
mem_phys = cv64ul(dv->dv_base) + position;
if (opcode == DEV_GATHER) { /* copy data */
sys_physcopy(NONE, PHYS_SEG, mem_phys,
proc_nr, D, user_vir, count);
} else {
sys_physcopy(proc_nr, D, user_vir,
NONE, PHYS_SEG, mem_phys, count);
}
break;
/* Random number generator. Character instead of block device. */
case RANDOM_DEV:
if (opcode == DEV_GATHER && !random_isseeded())
return(EAGAIN);
left = count;
while (left > 0) {
chunk = (left > RANDOM_BUF_SIZE) ? RANDOM_BUF_SIZE : left;
if (opcode == DEV_GATHER) {
random_getbytes(random_buf, chunk);
sys_vircopy(SELF, D, (vir_bytes) random_buf,
proc_nr, D, user_vir, chunk);
} else if (opcode == DEV_SCATTER) {
sys_vircopy(proc_nr, D, user_vir,
SELF, D, (vir_bytes) random_buf, chunk);
random_putbytes(random_buf, chunk);
}
user_vir += chunk;
left -= chunk;
}
break;
/* Null byte stream generator. */
case ZERO_DEV:
if (opcode == DEV_GATHER) {
left = count;
while (left > 0) {
chunk = (left > ZERO_BUF_SIZE) ? ZERO_BUF_SIZE : left;
if (OK != (s=sys_vircopy(SELF, D, (vir_bytes) dev_zero,
proc_nr, D, user_vir, chunk)))
report("MEM","sys_vircopy failed", s);
left -= chunk;
user_vir += chunk;
}
}
break;
/* Unknown (illegal) minor device. */
default:
return(EINVAL);
}
/* Book the number of bytes transferred. */
position += count;
iov->iov_addr += count;
if ((iov->iov_size -= count) == 0) { iov++; nr_req--; }
}
return(OK);
}
/*============================================================================*
* m_do_open *
*============================================================================*/
PRIVATE int m_do_open(dp, m_ptr)
struct driver *dp;
message *m_ptr;
{
/* Check device number on open. (This used to give I/O privileges to a
* process opening /dev/mem or /dev/kmem. This may be needed in case of
* memory mapped I/O. With system calls to do I/O this is no longer needed.)
*/
if (m_prepare(m_ptr->DEVICE) == NIL_DEV) return(ENXIO);
return(OK);
}
/*===========================================================================*
* m_init *
*===========================================================================*/
PRIVATE void m_init()
{
/* Initialize this task. All minor devices are initialized one by one. */
int i, s;
if (OK != (s=sys_getkinfo(&kinfo))) {
panic("MEM","Couldn't get kernel information.",s);
}
/* Install remote segment for /dev/kmem memory. */
m_geom[KMEM_DEV].dv_base = cvul64(kinfo.kmem_base);
m_geom[KMEM_DEV].dv_size = cvul64(kinfo.kmem_size);
if (OK != (s=sys_segctl(&m_seg[KMEM_DEV], (u16_t *) &s, (vir_bytes *) &s,
kinfo.kmem_base, kinfo.kmem_size))) {
panic("MEM","Couldn't install remote segment.",s);
}
/* Install remote segment for /dev/boot memory, if enabled. */
m_geom[BOOT_DEV].dv_base = cvul64(kinfo.bootdev_base);
m_geom[BOOT_DEV].dv_size = cvul64(kinfo.bootdev_size);
if (kinfo.bootdev_base > 0) {
if (OK != (s=sys_segctl(&m_seg[BOOT_DEV], (u16_t *) &s, (vir_bytes *) &s,
kinfo.bootdev_base, kinfo.bootdev_size))) {
panic("MEM","Couldn't install remote segment.",s);
}
}
/* Initialize /dev/zero. Simply write zeros into the buffer. */
for (i=0; i<ZERO_BUF_SIZE; i++) {
dev_zero[i] = '\0';
}
random_init();
m_random(NULL, NULL); /* also set periodic timer */
/* Set up memory ranges for /dev/mem. */
#if (CHIP == INTEL)
if (OK != (s=sys_getmachine(&machine))) {
panic("MEM","Couldn't get machine information.",s);
}
if (! machine.protected) {
m_geom[MEM_DEV].dv_size = cvul64(0x100000); /* 1M for 8086 systems */
} else {
#if _WORD_SIZE == 2
m_geom[MEM_DEV].dv_size = cvul64(0x1000000); /* 16M for 286 systems */
#else
m_geom[MEM_DEV].dv_size = cvul64(0xFFFFFFFF); /* 4G-1 for 386 systems */
#endif
}
#else /* !(CHIP == INTEL) */
#if (CHIP == M68000)
m_geom[MEM_DEV].dv_size = cvul64(MEM_BYTES);
#else /* !(CHIP == M68000) */
#error /* memory limit not set up */
#endif /* !(CHIP == M68000) */
#endif /* !(CHIP == INTEL) */
/* Initialization succeeded. Print welcome message. */
report("MEM","user-space memory driver has been initialized.", NO_NUM);
}
/*===========================================================================*
* m_ioctl *
*===========================================================================*/
PRIVATE int m_ioctl(dp, m_ptr)
struct driver *dp; /* pointer to driver structure */
message *m_ptr; /* pointer to control message */
{
/* I/O controls for the memory driver. Currently there is one I/O control:
* - MIOCRAMSIZE: to set the size of the RAM disk.
*/
struct device *dv;
if ((dv = m_prepare(m_ptr->DEVICE)) == NIL_DEV) return(ENXIO);
switch (m_ptr->REQUEST) {
case MIOCRAMSIZE: {
/* FS wants to create a new RAM disk with the given size. */
phys_bytes ramdev_size;
phys_bytes ramdev_base;
message m;
int s;
if (m_ptr->PROC_NR != FS_PROC_NR) {
report("MEM", "warning, MIOCRAMSIZE called by", m_ptr->PROC_NR);
return(EPERM);
}
/* Try to allocate a piece of memory for the RAM disk. */
ramdev_size = m_ptr->POSITION;
if (allocmem(ramdev_size, &ramdev_base) < 0) {
report("MEM", "warning, allocmem failed", errno);
return(ENOMEM);
}
dv->dv_base = cvul64(ramdev_base);
dv->dv_size = cvul64(ramdev_size);
if (OK != (s=sys_segctl(&m_seg[RAM_DEV], (u16_t *) &s, (vir_bytes *) &s,
ramdev_base, ramdev_size))) {
panic("MEM","Couldn't install remote segment.",s);
}
break;
}
default:
return(do_diocntl(&m_dtab, m_ptr));
}
return(OK);
}
/*============================================================================*
* m_random *
*============================================================================*/
PRIVATE void m_random(dp, m_ptr)
struct driver *dp; /* pointer to driver structure */
message *m_ptr; /* pointer to alarm message */
{
/* Fetch random information from the kernel to update /dev/random. */
int i, s, r_next, r_size, r_high;
struct randomness krandom;
if (OK != (s=sys_getrandomness(&krandom)))
report("MEM", "sys_getrandomness failed", s);
for (i= 0; i<RANDOM_SOURCES; i++)
{
r_next= krandom.bin[i].r_next;
r_size= krandom.bin[i].r_size;
r_high= r_next+r_size;
if (r_high <= RANDOM_ELEMENTS)
{
random_update(i, &krandom.bin[i].r_buf[r_next], r_size);
}
else
{
assert(r_next < RANDOM_ELEMENTS);
random_update(i, &krandom.bin[i].r_buf[r_next],
RANDOM_ELEMENTS-r_next);
random_update(i, &krandom.bin[i].r_buf[0],
r_high-RANDOM_ELEMENTS);
}
}
/* Schedule new alarm for next m_random call. */
if (OK != (s=sys_setalarm(KRANDOM_PERIOD, 0)))
report("MEM", "sys_setalarm failed", s);
}
/*============================================================================*
* m_geometry *
*============================================================================*/
PRIVATE void m_geometry(entry)
struct partition *entry;
{
/* Memory devices don't have a geometry, but the outside world insists. */
entry->cylinders = div64u(m_geom[m_device].dv_size, SECTOR_SIZE) / (64 * 32);
entry->heads = 64;
entry->sectors = 32;
}
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