diff options
| -rw-r--r-- | sysdeps/unix/sysv/linux/arm/ioperm.c | 63 |
1 files changed, 37 insertions, 26 deletions
diff --git a/sysdeps/unix/sysv/linux/arm/ioperm.c b/sysdeps/unix/sysv/linux/arm/ioperm.c index 260226d9f3..f4c9322823 100644 --- a/sysdeps/unix/sysv/linux/arm/ioperm.c +++ b/sysdeps/unix/sysv/linux/arm/ioperm.c @@ -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. + * + * 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>". * - * 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>". + * 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; } |