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Use sysctl by preference to obtain port mapping information. Avoid use of

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mprotect.
This commit is contained in:
Ulrich Drepper 2000-01-04 23:54:35 +00:00
parent 51fa0bed76
commit aba7548814
1 changed files with 37 additions and 26 deletions
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63
sysdeps/unix/sysv/linux/arm/ioperm.c
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@ -27,6 +27,12 @@
registers tend to be memory mapped these days so this should be no big
problem. */
/* Once upon a time this file used mprotect to enable and disable
access to particular areas of I/O space. Unfortunately the
mprotect syscall also has the side effect of enabling caching for
the area affected (this is a kernel limitation). So we now just
enable all the ports all of the time. */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
@ -39,6 +45,7 @@
#include <sys/mman.h>
#include <asm/page.h>
#include <sys/sysctl.h>
#define PATH_ARM_SYSTYPE "/etc/arm_systype"
#define PATH_CPUINFO "/proc/cpuinfo"
@ -69,16 +76,22 @@ static struct platform {
#define IO_ADDR(port) (io.base + ((port) << io.shift))
/*
* Initialize I/O system. To determine what I/O system we're dealing
* with, we first try to read the value of symlink PATH_ARM_SYSTYPE,
* if that fails, we lookup the "system type" field in /proc/cpuinfo.
* If that fails as well, we give up. Other possible options might be
* to look at the ELF auxiliary vector or to add a special system call
* but there is probably no point.
* Initialize I/O system. There are several ways to get the information
* we need. Each is tried in turn until one succeeds.
*
* If the value received from PATH_ARM_SYSTYPE begins with a number,
* assume this is a previously unsupported system and the values encode,
* in order, "<io_base>,<port_shift>".
* 1. Sysctl (CTL_BUS, BUS_ISA, ISA_*). This is the preferred method
* but not all kernels support it.
*
* 2. Read the value (not the contents) of symlink PATH_ARM_SYSTYPE.
* - If it matches one of the entries in the table above, use the
* corresponding values.
* - If it begins with a number, assume this is a previously
* unsupported system and the values encode, in order,
* "<io_base>,<port_shift>".
*
* 3. Lookup the "system type" field in /proc/cpuinfo. Again, if it
* matches an entry in the platform[] table, use the corresponding
* values.
*/
static int
@ -86,6 +99,16 @@ init_iosys (void)
{
char systype[256];
int i, n;
static int iobase_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_BASE };
static int ioshift_name[] = { CTL_BUS, BUS_ISA, BUS_ISA_PORT_SHIFT };
size_t len = sizeof(io.base);
if (! sysctl (iobase_name, 3, &io.io_base, &len, NULL, 0)
&& ! sysctl (ioshift_name, 3, &io.shift, &len, NULL, 0))
{
io.initdone = 1;
return 0;
}
n = readlink (PATH_ARM_SYSTYPE, systype, sizeof (systype) - 1);
if (n > 0)
@ -106,7 +129,7 @@ init_iosys (void)
FILE * fp;
fp = fopen (PATH_CPUINFO, "r");
if (!fp)
if (! fp)
return -1;
while ((n = fscanf (fp, "Hardware\t: %256[^\n]\n", systype))
!= EOF)
@ -149,10 +172,7 @@ init_iosys (void)
int
_ioperm (unsigned long int from, unsigned long int num, int turn_on)
{
unsigned long int addr, len;
int prot;
if (!io.initdone && init_iosys () < 0)
if (! io.initdone && init_iosys () < 0)
return -1;
/* this test isn't as silly as it may look like; consider overflows! */
@ -173,25 +193,16 @@ _ioperm (unsigned long int from, unsigned long int num, int turn_on)
return -1;
io.base =
(unsigned long int) __mmap (0, MAX_PORT << io.shift, PROT_NONE,
(unsigned long int) __mmap (0, MAX_PORT << io.shift,
PROT_READ | PROT_WRITE,
MAP_SHARED, fd, io.io_base);
close (fd);
if ((long) io.base == -1)
return -1;
}
prot = PROT_READ | PROT_WRITE;
}
else
{
if (!io.base)
return 0; /* never was turned on... */
/* turnoff access to relevant pages: */
prot = PROT_NONE;
}
addr = (io.base + (from << io.shift)) & PAGE_MASK;
len = num << io.shift;
return mprotect ((void *) addr, len, prot);
return 0;
}