x86: protect against sigaltstack wraparound
[linux-2.6] / arch / x86 / kernel / io_delay.c
1 /*
2  * I/O delay strategies for inb_p/outb_p
3  *
4  * Allow for a DMI based override of port 0x80, needed for certain HP laptops
5  * and possibly other systems. Also allow for the gradual elimination of
6  * outb_p/inb_p API uses.
7  */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/init.h>
11 #include <linux/delay.h>
12 #include <linux/dmi.h>
13 #include <asm/io.h>
14
15 int io_delay_type __read_mostly = CONFIG_DEFAULT_IO_DELAY_TYPE;
16 EXPORT_SYMBOL_GPL(io_delay_type);
17
18 static int __initdata io_delay_override;
19
20 /*
21  * Paravirt wants native_io_delay to be a constant.
22  */
23 void native_io_delay(void)
24 {
25         switch (io_delay_type) {
26         default:
27         case CONFIG_IO_DELAY_TYPE_0X80:
28                 asm volatile ("outb %al, $0x80");
29                 break;
30         case CONFIG_IO_DELAY_TYPE_0XED:
31                 asm volatile ("outb %al, $0xed");
32                 break;
33         case CONFIG_IO_DELAY_TYPE_UDELAY:
34                 /*
35                  * 2 usecs is an upper-bound for the outb delay but
36                  * note that udelay doesn't have the bus-level
37                  * side-effects that outb does, nor does udelay() have
38                  * precise timings during very early bootup (the delays
39                  * are shorter until calibrated):
40                  */
41                 udelay(2);
42         case CONFIG_IO_DELAY_TYPE_NONE:
43                 break;
44         }
45 }
46 EXPORT_SYMBOL(native_io_delay);
47
48 static int __init dmi_io_delay_0xed_port(const struct dmi_system_id *id)
49 {
50         if (io_delay_type == CONFIG_IO_DELAY_TYPE_0X80) {
51                 printk(KERN_NOTICE "%s: using 0xed I/O delay port\n",
52                         id->ident);
53                 io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
54         }
55
56         return 0;
57 }
58
59 /*
60  * Quirk table for systems that misbehave (lock up, etc.) if port
61  * 0x80 is used:
62  */
63 static struct dmi_system_id __initdata io_delay_0xed_port_dmi_table[] = {
64         {
65                 .callback       = dmi_io_delay_0xed_port,
66                 .ident          = "Compaq Presario V6000",
67                 .matches        = {
68                         DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
69                         DMI_MATCH(DMI_BOARD_NAME, "30B7")
70                 }
71         },
72         {
73                 .callback       = dmi_io_delay_0xed_port,
74                 .ident          = "HP Pavilion dv9000z",
75                 .matches        = {
76                         DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
77                         DMI_MATCH(DMI_BOARD_NAME, "30B9")
78                 }
79         },
80         {
81                 .callback       = dmi_io_delay_0xed_port,
82                 .ident          = "HP Pavilion tx1000",
83                 .matches        = {
84                         DMI_MATCH(DMI_BOARD_VENDOR, "Quanta"),
85                         DMI_MATCH(DMI_BOARD_NAME, "30BF")
86                 }
87         },
88         { }
89 };
90
91 void __init io_delay_init(void)
92 {
93         if (!io_delay_override)
94                 dmi_check_system(io_delay_0xed_port_dmi_table);
95 }
96
97 static int __init io_delay_param(char *s)
98 {
99         if (!strcmp(s, "0x80"))
100                 io_delay_type = CONFIG_IO_DELAY_TYPE_0X80;
101         else if (!strcmp(s, "0xed"))
102                 io_delay_type = CONFIG_IO_DELAY_TYPE_0XED;
103         else if (!strcmp(s, "udelay"))
104                 io_delay_type = CONFIG_IO_DELAY_TYPE_UDELAY;
105         else if (!strcmp(s, "none"))
106                 io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
107         else
108                 return -EINVAL;
109
110         io_delay_override = 1;
111         return 0;
112 }
113
114 early_param("io_delay", io_delay_param);