projects/linux·commit deb09dda

sb_edac: Avoid overflow errors at memory size calculation

deb09dda · Mauro Carvalho Chehab <[email protected]> · 2012-09-20 12:09:30 -03:00

Sandy bridge EDAC is calculating the memory size with overflow.
Basically, the size field and the integer calculation is using 32 bits.
More bits are needed, when the DIMM memories have high density.

The net result is that memories are improperly reported there, when
high-density DIMMs are used:

EDAC DEBUG: in drivers/edac/sb_edac.c, line at 591: mc#0: channel 0, dimm 0, -16384 Mb (-4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 591: mc#0: channel 1, dimm 0, -16384 Mb (-4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800

As the number of pages value is handled at the EDAC core as unsigned
ints, the driver shows the 16 GB memories at sysfs interface as 16760832
MB! The fix is simple: calculate the number of pages as unsigned 64-bits
integer.

After the patch, the memory size (16 GB) is properly detected:

EDAC DEBUG: in drivers/edac/sb_edac.c, line at 592: mc#0: channel 0, dimm 0, 16384 Mb (4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800
EDAC DEBUG: in drivers/edac/sb_edac.c, line at 592: mc#0: channel 1, dimm 0, 16384 Mb (4194304 pages) bank: 8, rank: 2, row: 0x10000, col: 0x800

Cc: [email protected]
Signed-off-by: Mauro Carvalho Chehab <[email protected]>
Commit
deb09ddaff1435f72dd598d38f9b58354c68a5ec
Parents
b70f8333

Changes

1 files changed · +4 −3

FileStatusAddDelContent
drivers/edac/sb_edac.cmodified+4−3View file

drivers/edac/sb_edac.c

View file
diff --git a/drivers/edac/sb_edac.c b/drivers/edac/sb_edac.c
index f3b1f9f..5715b7c 100644
--- a/drivers/edac/sb_edac.c
+++ b/drivers/edac/sb_edac.c
@@ -513,7 +513,8 @@ static int get_dimm_config(struct mem_ctl_info *mci)
{
struct sbridge_pvt *pvt = mci->pvt_info;
struct dimm_info *dimm;
- int i, j, banks, ranks, rows, cols, size, npages;
+ unsigned i, j, banks, ranks, rows, cols, npages;
+ u64 size;
u32 reg;
enum edac_type mode;
enum mem_type mtype;
@@ -585,10 +586,10 @@ static int get_dimm_config(struct mem_ctl_info *mci)
cols = numcol(mtr);
/* DDR3 has 8 I/O banks */
- size = (rows * cols * banks * ranks) >> (20 - 3);
+ size = ((u64)rows * cols * banks * ranks) >> (20 - 3);
npages = MiB_TO_PAGES(size);
- edac_dbg(0, "mc#%d: channel %d, dimm %d, %d Mb (%d pages) bank: %d, rank: %d, row: %#x, col: %#x\n",
+ edac_dbg(0, "mc#%d: channel %d, dimm %d, %Ld Mb (%d pages) bank: %d, rank: %d, row: %#x, col: %#x\n",
pvt->sbridge_dev->mc, i, j,
size, npages,
banks, ranks, rows, cols);