1// SPDX-License-Identifier: GPL-2.0
2#include <linux/kernel.h>
3#include <linux/types.h>
4#include <linux/init.h>
5#include <linux/memblock.h>
6#include <linux/seq_file.h>
7
8static bool early_memtest_done;
9static phys_addr_t early_memtest_bad_size;
10
11static u64 patterns[] __initdata = {
12 /* The first entry has to be 0 to leave memtest with zeroed memory */
13 0,
14 0xffffffffffffffffULL,
15 0x5555555555555555ULL,
16 0xaaaaaaaaaaaaaaaaULL,
17 0x1111111111111111ULL,
18 0x2222222222222222ULL,
19 0x4444444444444444ULL,
20 0x8888888888888888ULL,
21 0x3333333333333333ULL,
22 0x6666666666666666ULL,
23 0x9999999999999999ULL,
24 0xccccccccccccccccULL,
25 0x7777777777777777ULL,
26 0xbbbbbbbbbbbbbbbbULL,
27 0xddddddddddddddddULL,
28 0xeeeeeeeeeeeeeeeeULL,
29 0x7a6c7258554e494cULL, /* yeah ;-) */
30};
31
32static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
33{
34 pr_info(" %016llx bad mem addr %pa - %pa reserved\n",
35 cpu_to_be64(pattern), &start_bad, &end_bad);
36 memblock_reserve(base: start_bad, size: end_bad - start_bad);
37 early_memtest_bad_size += (end_bad - start_bad);
38}
39
40static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
41{
42 u64 *p, *start, *end;
43 phys_addr_t start_bad, last_bad;
44 phys_addr_t start_phys_aligned;
45 const size_t incr = sizeof(pattern);
46
47 start_phys_aligned = ALIGN(start_phys, incr);
48 start = __va(start_phys_aligned);
49 end = start + (size - (start_phys_aligned - start_phys)) / incr;
50 start_bad = 0;
51 last_bad = 0;
52
53 for (p = start; p < end; p++)
54 WRITE_ONCE(*p, pattern);
55
56 for (p = start; p < end; p++, start_phys_aligned += incr) {
57 if (READ_ONCE(*p) == pattern)
58 continue;
59 if (start_phys_aligned == last_bad + incr) {
60 last_bad += incr;
61 continue;
62 }
63 if (start_bad)
64 reserve_bad_mem(pattern, start_bad, end_bad: last_bad + incr);
65 start_bad = last_bad = start_phys_aligned;
66 }
67 if (start_bad)
68 reserve_bad_mem(pattern, start_bad, end_bad: last_bad + incr);
69
70 early_memtest_done = true;
71}
72
73static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
74{
75 u64 i;
76 phys_addr_t this_start, this_end;
77
78 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
79 &this_end, NULL) {
80 this_start = clamp(this_start, start, end);
81 this_end = clamp(this_end, start, end);
82 if (this_start < this_end) {
83 pr_info(" %pa - %pa pattern %016llx\n",
84 &this_start, &this_end, cpu_to_be64(pattern));
85 memtest(pattern, start_phys: this_start, size: this_end - this_start);
86 }
87 }
88}
89
90/* default is disabled */
91static unsigned int memtest_pattern __initdata;
92
93static int __init parse_memtest(char *arg)
94{
95 int ret = 0;
96
97 if (arg)
98 ret = kstrtouint(s: arg, base: 0, res: &memtest_pattern);
99 else
100 memtest_pattern = ARRAY_SIZE(patterns);
101
102 return ret;
103}
104
105early_param("memtest", parse_memtest);
106
107void __init early_memtest(phys_addr_t start, phys_addr_t end)
108{
109 unsigned int i;
110 unsigned int idx = 0;
111
112 if (!memtest_pattern)
113 return;
114
115 pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
116 for (i = memtest_pattern-1; i < UINT_MAX; --i) {
117 idx = i % ARRAY_SIZE(patterns);
118 do_one_pass(pattern: patterns[idx], start, end);
119 }
120}
121
122void memtest_report_meminfo(struct seq_file *m)
123{
124 unsigned long early_memtest_bad_size_kb;
125
126 if (!IS_ENABLED(CONFIG_PROC_FS))
127 return;
128
129 if (!early_memtest_done)
130 return;
131
132 early_memtest_bad_size_kb = early_memtest_bad_size >> 10;
133 if (early_memtest_bad_size && !early_memtest_bad_size_kb)
134 early_memtest_bad_size_kb = 1;
135 /* When 0 is reported, it means there actually was a successful test */
136 seq_printf(m, fmt: "EarlyMemtestBad: %5lu kB\n", early_memtest_bad_size_kb);
137}
138

source code of linux/mm/memtest.c