1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/init.h>
3 #include <linux/sched.h>
4 #include <linux/kthread.h>
5 #include <linux/workqueue.h>
6 #include <linux/memblock.h>
11 * Some BIOSes seem to corrupt the low 64k of memory during events
12 * like suspend/resume and unplugging an HDMI cable. Reserve all
13 * remaining free memory in that area and fill it with a distinct
16 #define MAX_SCAN_AREAS 8
18 static int __read_mostly memory_corruption_check
= -1;
20 static unsigned __read_mostly corruption_check_size
= 64*1024;
21 static unsigned __read_mostly corruption_check_period
= 60; /* seconds */
23 static struct scan_area
{
26 } scan_areas
[MAX_SCAN_AREAS
];
27 static int num_scan_areas
;
29 static __init
int set_corruption_check(char *arg
)
35 pr_err("memory_corruption_check config string not provided\n");
39 ret
= kstrtoul(arg
, 10, &val
);
43 memory_corruption_check
= val
;
46 early_param("memory_corruption_check", set_corruption_check
);
48 static __init
int set_corruption_check_period(char *arg
)
54 pr_err("memory_corruption_check_period config string not provided\n");
58 ret
= kstrtoul(arg
, 10, &val
);
62 corruption_check_period
= val
;
65 early_param("memory_corruption_check_period", set_corruption_check_period
);
67 static __init
int set_corruption_check_size(char *arg
)
73 pr_err("memory_corruption_check_size config string not provided\n");
77 size
= memparse(arg
, &end
);
80 corruption_check_size
= size
;
82 return (size
== corruption_check_size
) ? 0 : -EINVAL
;
84 early_param("memory_corruption_check_size", set_corruption_check_size
);
87 void __init
setup_bios_corruption_check(void)
89 phys_addr_t start
, end
;
92 if (memory_corruption_check
== -1) {
93 memory_corruption_check
=
94 #ifdef CONFIG_X86_BOOTPARAM_MEMORY_CORRUPTION_CHECK
102 if (corruption_check_size
== 0)
103 memory_corruption_check
= 0;
105 if (!memory_corruption_check
)
108 corruption_check_size
= round_up(corruption_check_size
, PAGE_SIZE
);
110 for_each_free_mem_range(i
, NUMA_NO_NODE
, MEMBLOCK_NONE
, &start
, &end
,
112 start
= clamp_t(phys_addr_t
, round_up(start
, PAGE_SIZE
),
113 PAGE_SIZE
, corruption_check_size
);
114 end
= clamp_t(phys_addr_t
, round_down(end
, PAGE_SIZE
),
115 PAGE_SIZE
, corruption_check_size
);
119 memblock_reserve(start
, end
- start
);
120 scan_areas
[num_scan_areas
].addr
= start
;
121 scan_areas
[num_scan_areas
].size
= end
- start
;
123 /* Assume we've already mapped this early memory */
124 memset(__va(start
), 0, end
- start
);
126 if (++num_scan_areas
>= MAX_SCAN_AREAS
)
131 printk(KERN_INFO
"Scanning %d areas for low memory corruption\n", num_scan_areas
);
135 void check_for_bios_corruption(void)
140 if (!memory_corruption_check
)
143 for (i
= 0; i
< num_scan_areas
; i
++) {
144 unsigned long *addr
= __va(scan_areas
[i
].addr
);
145 unsigned long size
= scan_areas
[i
].size
;
147 for (; size
; addr
++, size
-= sizeof(unsigned long)) {
150 printk(KERN_ERR
"Corrupted low memory at %p (%lx phys) = %08lx\n",
151 addr
, __pa(addr
), *addr
);
157 WARN_ONCE(corruption
, KERN_ERR
"Memory corruption detected in low memory\n");
160 static void check_corruption(struct work_struct
*dummy
);
161 static DECLARE_DELAYED_WORK(bios_check_work
, check_corruption
);
163 static void check_corruption(struct work_struct
*dummy
)
165 check_for_bios_corruption();
166 schedule_delayed_work(&bios_check_work
,
167 round_jiffies_relative(corruption_check_period
*HZ
));
170 static int start_periodic_check_for_corruption(void)
172 if (!num_scan_areas
|| !memory_corruption_check
|| corruption_check_period
== 0)
175 printk(KERN_INFO
"Scanning for low memory corruption every %d seconds\n",
176 corruption_check_period
);
178 /* First time we run the checks right away */
179 schedule_delayed_work(&bios_check_work
, 0);
182 device_initcall(start_periodic_check_for_corruption
);