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/*
* Page Deallocation Table (PDT) support
*
* The Page Deallocation Table (PDT) holds a table with pointers to bad
* memory (broken RAM modules) which is maintained by firmware.
*
* Copyright 2017 by Helge Deller <deller@gmx.de>
*
* TODO:
* - check regularily for new bad memory
* - add userspace interface with procfs or sysfs
* - increase number of PDT entries dynamically
*/
#include <linux/memblock.h>
#include <linux/seq_file.h>
#include <asm/pdc.h>
#include <asm/pdcpat.h>
#include <asm/sections.h>
#include <asm/pgtable.h>
enum pdt_access_type {
PDT_NONE,
PDT_PDC,
PDT_PAT_NEW,
PDT_PAT_OLD
};
static enum pdt_access_type pdt_type;
/* global PDT status information */
static struct pdc_mem_retinfo pdt_status;
#define MAX_PDT_TABLE_SIZE PAGE_SIZE
#define MAX_PDT_ENTRIES (MAX_PDT_TABLE_SIZE / sizeof(unsigned long))
static unsigned long pdt_entry[MAX_PDT_ENTRIES] __page_aligned_bss;
/* report PDT entries via /proc/meminfo */
void arch_report_meminfo(struct seq_file *m)
{
if (pdt_type == PDT_NONE)
return;
seq_printf(m, "PDT_max_entries: %7lu\n",
pdt_status.pdt_size);
seq_printf(m, "PDT_cur_entries: %7lu\n",
pdt_status.pdt_entries);
}
/*
* pdc_pdt_init()
*
* Initialize kernel PDT structures, read initial PDT table from firmware,
* report all current PDT entries and mark bad memory with memblock_reserve()
* to avoid that the kernel will use broken memory areas.
*
*/
void __init pdc_pdt_init(void)
{
int ret, i;
unsigned long entries;
struct pdc_mem_read_pdt pdt_read_ret;
if (is_pdc_pat()) {
struct pdc_pat_mem_retinfo pat_rinfo;
pdt_type = PDT_PAT_NEW;
ret = pdc_pat_mem_pdt_info(&pat_rinfo);
pdt_status.pdt_size = pat_rinfo.max_pdt_entries;
pdt_status.pdt_entries = pat_rinfo.current_pdt_entries;
pdt_status.pdt_status = 0;
pdt_status.first_dbe_loc = pat_rinfo.first_dbe_loc;
pdt_status.good_mem = pat_rinfo.good_mem;
} else {
pdt_type = PDT_PDC;
ret = pdc_mem_pdt_info(&pdt_status);
}
if (ret != PDC_OK) {
pdt_type = PDT_NONE;
pr_info("PDT: Firmware does not provide any page deallocation"
" information.\n");
return;
}
entries = pdt_status.pdt_entries;
WARN_ON(entries > MAX_PDT_ENTRIES);
pr_info("PDT: size %lu, entries %lu, status %lu, dbe_loc 0x%lx,"
" good_mem %lu\n",
pdt_status.pdt_size, pdt_status.pdt_entries,
pdt_status.pdt_status, pdt_status.first_dbe_loc,
pdt_status.good_mem);
if (entries == 0) {
pr_info("PDT: Firmware reports all memory OK.\n");
return;
}
if (pdt_status.first_dbe_loc &&
pdt_status.first_dbe_loc <= __pa((unsigned long)&_end))
pr_crit("CRITICAL: Bad memory inside kernel image memory area!\n");
pr_warn("PDT: Firmware reports %lu entries of faulty memory:\n",
entries);
if (pdt_type == PDT_PDC)
ret = pdc_mem_pdt_read_entries(&pdt_read_ret, pdt_entry);
else {
#ifdef CONFIG_64BIT
struct pdc_pat_mem_read_pd_retinfo pat_pret;
ret = pdc_pat_mem_read_cell_pdt(&pat_pret, pdt_entry,
MAX_PDT_ENTRIES);
if (ret != PDC_OK) {
pdt_type = PDT_PAT_OLD;
ret = pdc_pat_mem_read_pd_pdt(&pat_pret, pdt_entry,
MAX_PDT_TABLE_SIZE, 0);
}
#else
ret = PDC_BAD_PROC;
#endif
}
if (ret != PDC_OK) {
pdt_type = PDT_NONE;
pr_debug("PDT type %d, retval = %d\n", pdt_type, ret);
return;
}
for (i = 0; i < pdt_status.pdt_entries; i++) {
if (i < 20)
pr_warn("PDT: BAD PAGE #%d at 0x%08lx (error_type = %lu)\n",
i,
pdt_entry[i] & PAGE_MASK,
pdt_entry[i] & 1);
/* mark memory page bad */
memblock_reserve(pdt_entry[i] & PAGE_MASK, PAGE_SIZE);
}
}
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