Em Thu, 10 Oct 2019 20:25:37 +0000 Robert Richter <rrich...@marvell.com> escreveu:
> 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 up. > > Suggested-by: James Morse <james.mo...@arm.com> > Signed-off-by: Robert Richter <rrich...@marvell.com> Reviewed-by: Mauro Carvalho Chehab <mchehab+sams...@kernel.org> > --- > 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 851aad92e42d..97242cf18a88 100644 > --- a/drivers/edac/ghes_edac.c > +++ b/drivers/edac/ghes_edac.c > @@ -220,6 +220,7 @@ void ghes_edac_report_mem_error(int sev, struct > cper_sec_mem_err *mem_err) > /* 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; > @@ -315,7 +316,7 @@ void ghes_edac_report_mem_error(int sev, struct > cper_sec_mem_err *mem_err) > > /* 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; > @@ -428,8 +429,13 @@ void ghes_edac_report_mem_error(int sev, struct > cper_sec_mem_err *mem_err) > 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(e->type, e->msg, e->label, e->error_count, Thanks, Mauro
