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
7bool early_memtest_done;
8phys_addr_t early_memtest_bad_size;
9
10static u64 patterns[] __initdata = {
11 /* The first entry has to be 0 to leave memtest with zeroed memory */
12 0,
13 0xffffffffffffffffULL,
14 0x5555555555555555ULL,
15 0xaaaaaaaaaaaaaaaaULL,
16 0x1111111111111111ULL,
17 0x2222222222222222ULL,
18 0x4444444444444444ULL,
19 0x8888888888888888ULL,
20 0x3333333333333333ULL,
21 0x6666666666666666ULL,
22 0x9999999999999999ULL,
23 0xccccccccccccccccULL,
24 0x7777777777777777ULL,
25 0xbbbbbbbbbbbbbbbbULL,
26 0xddddddddddddddddULL,
27 0xeeeeeeeeeeeeeeeeULL,
28 0x7a6c7258554e494cULL, /* yeah ;-) */
29};
30
31static void __init reserve_bad_mem(u64 pattern, phys_addr_t start_bad, phys_addr_t end_bad)
32{
33 pr_info(" %016llx bad mem addr %pa - %pa reserved\n",
34 cpu_to_be64(pattern), &start_bad, &end_bad);
35 memblock_reserve(base: start_bad, size: end_bad - start_bad);
36 early_memtest_bad_size += (end_bad - start_bad);
37}
38
39static void __init memtest(u64 pattern, phys_addr_t start_phys, phys_addr_t size)
40{
41 u64 *p, *start, *end;
42 phys_addr_t start_bad, last_bad;
43 phys_addr_t start_phys_aligned;
44 const size_t incr = sizeof(pattern);
45
46 start_phys_aligned = ALIGN(start_phys, incr);
47 start = __va(start_phys_aligned);
48 end = start + (size - (start_phys_aligned - start_phys)) / incr;
49 start_bad = 0;
50 last_bad = 0;
51
52 for (p = start; p < end; p++)
53 *p = pattern;
54
55 for (p = start; p < end; p++, start_phys_aligned += incr) {
56 if (*p == pattern)
57 continue;
58 if (start_phys_aligned == last_bad + incr) {
59 last_bad += incr;
60 continue;
61 }
62 if (start_bad)
63 reserve_bad_mem(pattern, start_bad, last_bad + incr);
64 start_bad = last_bad = start_phys_aligned;
65 }
66 if (start_bad)
67 reserve_bad_mem(pattern, start_bad, last_bad + incr);
68
69 early_memtest_done = true;
70}
71
72static void __init do_one_pass(u64 pattern, phys_addr_t start, phys_addr_t end)
73{
74 u64 i;
75 phys_addr_t this_start, this_end;
76
77 for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE, &this_start,
78 &this_end, NULL) {
79 this_start = clamp(this_start, start, end);
80 this_end = clamp(this_end, start, end);
81 if (this_start < this_end) {
82 pr_info(" %pa - %pa pattern %016llx\n",
83 &this_start, &this_end, cpu_to_be64(pattern));
84 memtest(pattern, this_start, this_end - this_start);
85 }
86 }
87}
88
89/* default is disabled */
90static unsigned int memtest_pattern __initdata;
91
92static int __init parse_memtest(char *arg)
93{
94 int ret = 0;
95
96 if (arg)
97 ret = kstrtouint(s: arg, base: 0, res: &memtest_pattern);
98 else
99 memtest_pattern = ARRAY_SIZE(patterns);
100
101 return ret;
102}
103
104early_param("memtest", parse_memtest);
105
106void __init early_memtest(phys_addr_t start, phys_addr_t end)
107{
108 unsigned int i;
109 unsigned int idx = 0;
110
111 if (!memtest_pattern)
112 return;
113
114 pr_info("early_memtest: # of tests: %u\n", memtest_pattern);
115 for (i = memtest_pattern-1; i < UINT_MAX; --i) {
116 idx = i % ARRAY_SIZE(patterns);
117 do_one_pass(patterns[idx], start, end);
118 }
119}
120

source code of linux/mm/memtest.c