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x86: fix mttr trimming 

Pavel Emelyanov reported that his networking card did not work
and bisected it down to:

"
The commit

  093af8d7f0
  x86_32: trim memory by updating e820

broke my e1000 card: on loading driver says that

  e1000: probe of 0000:04:03.0 failed with error -5

and the interface doesn't appear.
"

on a 32-bit kernel, base will overflow when try to do PAGE_SHIFT,
and highest_addr will always less 4G.

So use pfn instead of address to avoid the overflow when more than
4g RAM is installed on a 32-bit kernel.

Many thanks to Pavel Emelyanov for reporting and testing it.

Bisected-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Tested-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Yinghai Lu 2008-02-06 22:39:45 +01:00 committed by Ingo Molnar
parent 971a52d66a
commit 20651af9ac
1 changed files with 9 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
arch/x86/kernel/cpu/mtrr/main.c
View File

@ -659,7 +659,7 @@ static __init int amd_special_default_mtrr(void)
*/ */
int __init mtrr_trim_uncached_memory(unsigned long end_pfn) int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
{ {
unsigned long i, base, size, highest_addr = 0, def, dummy; unsigned long i, base, size, highest_pfn = 0, def, dummy;
mtrr_type type; mtrr_type type;
u64 trim_start, trim_size; u64 trim_start, trim_size;
@ -682,28 +682,27 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn)
mtrr_if->get(i, &base, &size, &type); mtrr_if->get(i, &base, &size, &type);
if (type != MTRR_TYPE_WRBACK) if (type != MTRR_TYPE_WRBACK)
continue; continue;
base <<= PAGE_SHIFT; if (highest_pfn < base + size)
size <<= PAGE_SHIFT; highest_pfn = base + size;
if (highest_addr < base + size)
highest_addr = base + size;
} }
/* kvm/qemu doesn't have mtrr set right, don't trim them all */ /* kvm/qemu doesn't have mtrr set right, don't trim them all */
if (!highest_addr) { if (!highest_pfn) {
printk(KERN_WARNING "WARNING: strange, CPU MTRRs all blank?\n"); printk(KERN_WARNING "WARNING: strange, CPU MTRRs all blank?\n");
WARN_ON(1); WARN_ON(1);
return 0; return 0;
} }
if ((highest_addr >> PAGE_SHIFT) < end_pfn) { if (highest_pfn < end_pfn) {
printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover" printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover"
" all of memory, losing %LdMB of RAM.\n", " all of memory, losing %luMB of RAM.\n",
(((u64)end_pfn << PAGE_SHIFT) - highest_addr) >> 20); (end_pfn - highest_pfn) >> (20 - PAGE_SHIFT));
WARN_ON(1); WARN_ON(1);
printk(KERN_INFO "update e820 for mtrr\n"); printk(KERN_INFO "update e820 for mtrr\n");
trim_start = highest_addr; trim_start = highest_pfn;
trim_start <<= PAGE_SHIFT;
trim_size = end_pfn; trim_size = end_pfn;
trim_size <<= PAGE_SHIFT; trim_size <<= PAGE_SHIFT;
trim_size -= trim_start; trim_size -= trim_start;