From: Robert Richter <rrichter@xxxxxxxxxxx> [ Upstream commit 7088e29e0423d3195e09079b4f849ec4837e5a75 ] The current code to convert a physical address mask to a grain (defined as granularity in bytes) is: e->grain = ~(mem_err->physical_addr_mask & ~PAGE_MASK); This is broken in several ways: 1) It calculates to wrong grain values. E.g., a physical address mask of ~0xfff should give a grain of 0x1000. Without considering PAGE_MASK, there is an off-by-one. Things are worse when also filtering it with ~PAGE_MASK. This will calculate to a grain with the upper bits set. In the example it even calculates to ~0. 2) The grain does not depend on and is unrelated to the kernel's page-size. The page-size only matters when unmapping memory in memory_failure(). Smaller grains are wrongly rounded up to the page-size, on architectures with a configurable page-size (e.g. arm64) this could round up to the even bigger page-size of the hypervisor. Fix this with: e->grain = ~mem_err->physical_addr_mask + 1; The grain_bits are defined as: grain = 1 << grain_bits; Change also the grain_bits calculation accordingly, it is the same formula as in edac_mc.c now and the code can be unified. The value in ->physical_addr_mask coming from firmware is assumed to be contiguous, but this is not sanity-checked. However, in case the mask is non-contiguous, a conversion to grain_bits effectively converts the grain bit mask to a power of 2 by rounding it up. Suggested-by: James Morse <james.morse@xxxxxxx> Signed-off-by: Robert Richter <rrichter@xxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@xxxxxxxxxx> Cc: "linux-edac@xxxxxxxxxxxxxxx" <linux-edac@xxxxxxxxxxxxxxx> Cc: Tony Luck <tony.luck@xxxxxxxxx> Link: https://lkml.kernel.org/r/20191106093239.25517-11-rrichter@xxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/edac/ghes_edac.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/edac/ghes_edac.c b/drivers/edac/ghes_edac.c index e3fa4390f8460..4ddbf6604e2ab 100644 --- a/drivers/edac/ghes_edac.c +++ b/drivers/edac/ghes_edac.c @@ -189,6 +189,7 @@ void ghes_edac_report_mem_error(struct ghes *ghes, int sev, /* Cleans the error report buffer */ memset(e, 0, sizeof (*e)); e->error_count = 1; + e->grain = 1; strcpy(e->label, "unknown label"); e->msg = pvt->msg; e->other_detail = pvt->other_detail; @@ -284,7 +285,7 @@ void ghes_edac_report_mem_error(struct ghes *ghes, int sev, /* Error grain */ if (mem_err->validation_bits & CPER_MEM_VALID_PA_MASK) - e->grain = ~(mem_err->physical_addr_mask & ~PAGE_MASK); + e->grain = ~mem_err->physical_addr_mask + 1; /* Memory error location, mapped on e->location */ p = e->location; @@ -391,8 +392,13 @@ void ghes_edac_report_mem_error(struct ghes *ghes, int sev, if (p > pvt->other_detail) *(p - 1) = '\0'; + /* Sanity-check driver-supplied grain value. */ + if (WARN_ON_ONCE(!e->grain)) + e->grain = 1; + + grain_bits = fls_long(e->grain - 1); + /* Generate the trace event */ - grain_bits = fls_long(e->grain); snprintf(pvt->detail_location, sizeof(pvt->detail_location), "APEI location: %s %s", e->location, e->other_detail); trace_mc_event(type, e->msg, e->label, e->error_count, -- 2.20.1
