From: Robert Richter <[email protected]>
[ Upstream commit 3724ace582d9f675134985727fd5e9811f23c059 ]
The grain in EDAC is defined as "minimum granularity for an error
report, in bytes". The following calculation of the grain_bits in
edac_mc is wrong:
grain_bits = fls_long(e->grain) + 1;
Where grain_bits is defined as:
grain = 1 << grain_bits
Example:
grain = 8 # 64 bit (8 bytes)
grain_bits = fls_long(8) + 1
grain_bits = 4 + 1 = 5
grain = 1 << grain_bits
grain = 1 << 5 = 32
Replace it with the correct calculation:
grain_bits = fls_long(e->grain - 1);
The example gives now:
grain_bits = fls_long(8 - 1)
grain_bits = fls_long(7)
grain_bits = 3
grain = 1 << 3 = 8
Also, check if the hardware reports a reasonable grain != 0 and fallback
with a warning to 1 byte granularity otherwise.
[ bp: massage a bit. ]
Signed-off-by: Robert Richter <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Cc: "[email protected]" <[email protected]>
Cc: James Morse <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Tony Luck <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sasha Levin <[email protected]>
---
drivers/edac/edac_mc.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/edac/edac_mc.c b/drivers/edac/edac_mc.c
index 64922c8fa7e3b..d899d86897d06 100644
--- a/drivers/edac/edac_mc.c
+++ b/drivers/edac/edac_mc.c
@@ -1235,9 +1235,13 @@ void edac_mc_handle_error(const enum
hw_event_mc_err_type type,
if (p > e->location)
*(p - 1) = '\0';
- /* Report the error via the trace interface */
- grain_bits = fls_long(e->grain) + 1;
+ /* Sanity-check driver-supplied grain value. */
+ if (WARN_ON_ONCE(!e->grain))
+ e->grain = 1;
+
+ grain_bits = fls_long(e->grain - 1);
+ /* Report the error via the trace interface */
if (IS_ENABLED(CONFIG_RAS))
trace_mc_event(type, e->msg, e->label, e->error_count,
mci->mc_idx, e->top_layer, e->mid_layer,
--
2.20.1
