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Subject[PATCH] x86_64: early memtest to find bad ram
Date
From

do simple memtest after init_memory_mapping

use find_e820_area_size to find all ram range that is not reserved.

and do some simple bits test to find some bad ram.

if find some bad ram, use reserve_early to exclude that range.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

Index: linux-2.6/arch/x86/kernel/e820_64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/e820_64.c
+++ linux-2.6/arch/x86/kernel/e820_64.c
@@ -119,6 +119,40 @@ again:
return changed;
}

+/* Check for already reserved areas */
+static inline int
+bad_addr_size(unsigned long *addrp, unsigned long *sizep, unsigned long align)
+{
+ int i;
+ unsigned long addr = *addrp, last;
+ unsigned long size = *sizep;
+ int changed = 0;
+again:
+ last = addr + size;
+ for (i = 0; i < MAX_EARLY_RES && early_res[i].end; i++) {
+ struct early_res *r = &early_res[i];
+ if (last > r->start && addr < r->start) {
+ size = r->start - addr;
+ changed = 1;
+ goto again;
+ }
+ if (last > r->end && addr < r->end) {
+ addr = round_up(r->end, align);
+ size = last - addr;
+ changed = 1;
+ goto again;
+ }
+ if (last <= r->end && addr >= r->start) {
+ (*sizep)++;
+ return 0;
+ }
+ }
+ if (changed) {
+ *addrp = addr;
+ *sizep = size;
+ }
+ return changed;
+}
/*
* This function checks if any part of the range <start,end> is mapped
* with type.
@@ -195,7 +229,7 @@ unsigned long __init find_e820_area(unsi
ei_last = ei->addr + ei->size;
if (addr < start)
addr = round_up(start, align);
- if (addr > ei_last)
+ if (addr >= ei_last)
continue;
while (bad_addr(&addr, size, align) && addr+size <= ei_last)
;
@@ -210,6 +244,40 @@ unsigned long __init find_e820_area(unsi
}

/*
+ * Find next free range after *start
+ */
+unsigned long __init find_e820_area_size(unsigned long start, unsigned long *sizep, unsigned long align)
+{
+ int i;
+
+ for (i = 0; i < e820.nr_map; i++) {
+ struct e820entry *ei = &e820.map[i];
+ unsigned long addr, last;
+ unsigned long ei_last;
+
+ if (ei->type != E820_RAM)
+ continue;
+ addr = round_up(ei->addr, align);
+ ei_last = ei->addr + ei->size;
+// printk(KERN_DEBUG "find_e820_area_size : e820 %d [%llx, %lx]\n", i, ei->addr, ei_last);
+ if (addr < start)
+ addr = round_up(start, align);
+// printk(KERN_DEBUG "find_e820_area_size : 0 [%lx, %lx]\n", addr, ei_last);
+ if (addr >= ei_last)
+ continue;
+ *sizep = ei_last - addr;
+ while (bad_addr_size(&addr, sizep, align) && addr+ *sizep <= ei_last)
+ ;
+ last = addr + *sizep;
+// printk(KERN_DEBUG "find_e820_area_size : 1 [%lx, %lx]\n", addr, last);
+ if (last > ei_last)
+ continue;
+ return addr;
+ }
+ return -1UL;
+
+}
+/*
* Find the highest page frame number we have available
*/
unsigned long __init e820_end_of_ram(void)
Index: linux-2.6/arch/x86/mm/init_64.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init_64.c
+++ linux-2.6/arch/x86/mm/init_64.c
@@ -427,6 +427,106 @@ static void __init init_gbpages(void)
direct_gbpages = 0;
}

+static void __init memtest(unsigned long start_phys, unsigned long size, unsigned pattern)
+{
+ unsigned long i;
+ unsigned long *start;
+ unsigned long start_bad;
+ unsigned long last_bad;
+ unsigned long val;
+ unsigned long start_phys_aligned;
+ unsigned long count;
+ unsigned long incr;
+
+ switch (pattern) {
+ case 0:
+ val = 0UL;
+ break;
+ case 1:
+ val = -1UL;
+ break;
+ case 2:
+ val = 0x5555555555555555UL;
+ break;
+ case 3:
+ val = 0xaaaaaaaaaaaaaaaaUL;
+ break;
+ default:
+ return;
+ }
+
+ incr = sizeof(unsigned long);
+ start_phys_aligned = ALIGN(start_phys, incr);
+ count = (size - (start_phys_aligned - start_phys))/incr;
+ start = __va(start_phys_aligned);
+ start_bad = 0;
+ last_bad = 0;
+
+ for (i = 0; i < count; i++)
+ start[i] = val;
+ for (i = 0; i < count; i++, start++, start_phys_aligned += incr) {
+ if (*start != val) {
+ if (start_phys_aligned == last_bad + incr) {
+ last_bad += incr;
+ } else {
+ if (start_bad) {
+ printk(KERN_INFO " %016lxx bad mem addr %016lx - %016lx reserved\n",
+ val, start_bad, last_bad + incr);
+ reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+ }
+ start_bad = last_bad = start_phys_aligned;
+ }
+ }
+ }
+ if (start_bad) {
+ printk(KERN_INFO " %016lx bad mem addr %016lx - %016lx reserved\n",
+ val, start_bad, last_bad + incr);
+ reserve_early(start_bad, last_bad - start_bad, "BAD RAM");
+ }
+
+}
+
+static int __initdata memtest_pattern;
+static int __init parse_memtest(char *arg)
+{
+ if (arg)
+ memtest_pattern = simple_strtoul(arg, NULL, 0) + 1;
+ return 0;
+}
+
+early_param("memtest", parse_memtest);
+
+static void __init early_memtest(unsigned long start, unsigned long end)
+{
+ unsigned long t_start, t_size;
+ unsigned pattern;
+
+ if (memtest_pattern)
+ printk(KERN_INFO "early_memtest: pattern num %d", memtest_pattern);
+ for (pattern = 0; pattern < memtest_pattern; pattern++) {
+ t_start = start;
+ t_size = 0;
+ while (t_start < end) {
+ t_start = find_e820_area_size(t_start, &t_size, 1);
+
+ /* done ? */
+ if (t_start >= end)
+ break;
+ if (t_start + t_size > end)
+ t_size = end - t_start;
+
+ printk(KERN_CONT "\n %016lx - %016lx pattern %d",
+ t_start, t_start + t_size, pattern);
+
+ memtest(t_start, t_size, pattern);
+
+ t_start += t_size;
+ }
+ }
+ if (memtest_pattern)
+ printk(KERN_CONT "\n");
+}
+
/*
* Setup the direct mapping of the physical memory at PAGE_OFFSET.
* This runs before bootmem is initialized and gets pages directly from
@@ -435,8 +535,9 @@ static void __init init_gbpages(void)
void __init_refok init_memory_mapping(unsigned long start, unsigned long end)
{
unsigned long next;
+ unsigned long start_phys = start, end_phys = end;

- pr_debug("init_memory_mapping\n");
+ printk(KERN_INFO "init_memory_mapping\n");

/*
* Find space for the kernel direct mapping tables.
@@ -479,6 +580,9 @@ void __init_refok init_memory_mapping(un
if (!after_bootmem)
reserve_early(table_start << PAGE_SHIFT,
table_end << PAGE_SHIFT, "PGTABLE");
+
+ if (!after_bootmem)
+ early_memtest(start_phys, end_phys);
}

#ifndef CONFIG_NUMA
Index: linux-2.6/include/asm-x86/e820_64.h
===================================================================
--- linux-2.6.orig/include/asm-x86/e820_64.h
+++ linux-2.6/include/asm-x86/e820_64.h
@@ -16,6 +16,9 @@
#ifndef __ASSEMBLY__
extern unsigned long find_e820_area(unsigned long start, unsigned long end,
unsigned long size, unsigned long align);
+extern unsigned long find_e820_area_size(unsigned long start,
+ unsigned long *sizep,
+ unsigned long align);
extern void add_memory_region(unsigned long start, unsigned long size,
int type);
extern void update_memory_range(u64 start, u64 size, unsigned old_type,

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