2 * Page Deallocation Table (PDT) support
4 * The Page Deallocation Table (PDT) holds a table with pointers to bad
5 * memory (broken RAM modules) which is maintained by firmware.
7 * Copyright 2017 by Helge Deller <deller@gmx.de>
10 * - check regularily for new bad memory
11 * - add userspace interface with procfs or sysfs
12 * - increase number of PDT entries dynamically
15 #include <linux/memblock.h>
16 #include <linux/seq_file.h>
19 #include <asm/pdcpat.h>
20 #include <asm/sections.h>
21 #include <asm/pgtable.h>
23 enum pdt_access_type {
30 static enum pdt_access_type pdt_type;
32 /* global PDT status information */
33 static struct pdc_mem_retinfo pdt_status;
35 #define MAX_PDT_TABLE_SIZE PAGE_SIZE
36 #define MAX_PDT_ENTRIES (MAX_PDT_TABLE_SIZE / sizeof(unsigned long))
37 static unsigned long pdt_entry[MAX_PDT_ENTRIES] __page_aligned_bss;
40 /* report PDT entries via /proc/meminfo */
41 void arch_report_meminfo(struct seq_file *m)
43 if (pdt_type == PDT_NONE)
46 seq_printf(m, "PDT_max_entries: %7lu\n",
48 seq_printf(m, "PDT_cur_entries: %7lu\n",
49 pdt_status.pdt_entries);
55 * Initialize kernel PDT structures, read initial PDT table from firmware,
56 * report all current PDT entries and mark bad memory with memblock_reserve()
57 * to avoid that the kernel will use broken memory areas.
60 void __init pdc_pdt_init(void)
63 unsigned long entries;
64 struct pdc_mem_read_pdt pdt_read_ret;
67 struct pdc_pat_mem_retinfo pat_rinfo;
69 pdt_type = PDT_PAT_NEW;
70 ret = pdc_pat_mem_pdt_info(&pat_rinfo);
71 pdt_status.pdt_size = pat_rinfo.max_pdt_entries;
72 pdt_status.pdt_entries = pat_rinfo.current_pdt_entries;
73 pdt_status.pdt_status = 0;
74 pdt_status.first_dbe_loc = pat_rinfo.first_dbe_loc;
75 pdt_status.good_mem = pat_rinfo.good_mem;
78 ret = pdc_mem_pdt_info(&pdt_status);
83 pr_info("PDT: Firmware does not provide any page deallocation"
88 entries = pdt_status.pdt_entries;
89 WARN_ON(entries > MAX_PDT_ENTRIES);
91 pr_info("PDT: size %lu, entries %lu, status %lu, dbe_loc 0x%lx,"
93 pdt_status.pdt_size, pdt_status.pdt_entries,
94 pdt_status.pdt_status, pdt_status.first_dbe_loc,
98 pr_info("PDT: Firmware reports all memory OK.\n");
102 if (pdt_status.first_dbe_loc &&
103 pdt_status.first_dbe_loc <= __pa((unsigned long)&_end))
104 pr_crit("CRITICAL: Bad memory inside kernel image memory area!\n");
106 pr_warn("PDT: Firmware reports %lu entries of faulty memory:\n",
109 if (pdt_type == PDT_PDC)
110 ret = pdc_mem_pdt_read_entries(&pdt_read_ret, pdt_entry);
113 struct pdc_pat_mem_read_pd_retinfo pat_pret;
115 /* try old obsolete PAT firmware function first */
116 pdt_type = PDT_PAT_OLD;
117 ret = pdc_pat_mem_read_cell_pdt(&pat_pret, pdt_entry,
120 pdt_type = PDT_PAT_NEW;
121 ret = pdc_pat_mem_read_pd_pdt(&pat_pret, pdt_entry,
122 MAX_PDT_TABLE_SIZE, 0);
131 pr_debug("PDT type %d, retval = %d\n", pdt_type, ret);
135 for (i = 0; i < pdt_status.pdt_entries; i++) {
136 struct pdc_pat_mem_phys_mem_location loc;
138 /* get DIMM slot number */
139 loc.dimm_slot = 0xff;
141 pdc_pat_mem_get_dimm_phys_location(&loc, pdt_entry[i]);
144 pr_warn("PDT: BAD PAGE #%d at 0x%08lx, "
145 "DIMM slot %02x (error_type = %lu)\n",
147 pdt_entry[i] & PAGE_MASK,
151 /* mark memory page bad */
152 memblock_reserve(pdt_entry[i] & PAGE_MASK, PAGE_SIZE);