mm/memtest.c

   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
   8 static bool early_memtest_done;
   9 static phys_addr_t early_memtest_bad_size;
  10
  11 static 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
  32 static 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(start_bad, end_bad - start_bad);
  37         early_memtest_bad_size += (end_bad - start_bad);
  38 }
  39
  40 static 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, last_bad + incr);
  65                 start_bad = last_bad = start_phys_aligned;
  66         }
  67         if (start_bad)
  68                 reserve_bad_mem(pattern, start_bad, last_bad + incr);
  69
  70         early_memtest_done = true;
  71 }
  72
  73 static 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, this_start, this_end - this_start);
  86                 }
  87         }
  88 }
  89
  90 /* default is disabled */
  91 static unsigned int memtest_pattern __initdata;
  92
  93 static int __init parse_memtest(char *arg)
  94 {
  95         int ret = 0;
  96
  97         if (arg)
  98                 ret = kstrtouint(arg, 0, &memtest_pattern);
  99         else
 100                 memtest_pattern = ARRAY_SIZE(patterns);
 101
 102         return ret;
 103 }
 104
 105 early_param("memtest", parse_memtest);
 106
 107 void __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(patterns[idx], start, end);
 119         }
 120 }
 121
 122 void 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, "EarlyMemtestBad:   %5lu kB\n", early_memtest_bad_size_kb);
 137 }