On Tue, Sep 22, 2020 at 11:41:28AM +0200, Ard Biesheuvel wrote: > The TPM event log is provided to the OS by the firmware, by loading > it into an area in memory and passing the physical address via a node > in the device tree. > > Currently, we use __va() to access the memory via the kernel's linear > map: however, it is not guaranteed that the linear map covers this > particular address, as we may be running under HIGHMEM on a 32-bit > architecture, or running firmware that uses a memory type for the > event log that is omitted from the linear map (such as EfiReserved). Makes perfect sense to the level that I wonder if this should have a fixes tag and/or needs to be backported to the stable kernels? > So instead, use memremap(), which will reuse the linear mapping if > it is valid, or create another mapping otherwise. > > Cc: Peter Huewe <peterhuewe@xxxxxx> > Cc: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> > Cc: Jason Gunthorpe <jgg@xxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > --- > drivers/char/tpm/eventlog/of.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/char/tpm/eventlog/of.c b/drivers/char/tpm/eventlog/of.c > index a9ce66d09a75..9178547589a3 100644 > --- a/drivers/char/tpm/eventlog/of.c > +++ b/drivers/char/tpm/eventlog/of.c > @@ -11,6 +11,7 @@ > */ > > #include <linux/slab.h> > +#include <linux/io.h> > #include <linux/of.h> > #include <linux/tpm_eventlog.h> > > @@ -25,6 +26,7 @@ int tpm_read_log_of(struct tpm_chip *chip) > struct tpm_bios_log *log; > u32 size; > u64 base; > + void *p; I'd just use 'ptr' for readability sake. > log = &chip->log; > if (chip->dev.parent && chip->dev.parent->of_node) > @@ -65,7 +67,11 @@ int tpm_read_log_of(struct tpm_chip *chip) > return -EIO; > } > > - log->bios_event_log = kmemdup(__va(base), size, GFP_KERNEL); > + p = memremap(base, size, MEMREMAP_WB); > + if (!p) > + return -ENOMEM; > + log->bios_event_log = kmemdup(p, size, GFP_KERNEL); > + memunmap(p); > if (!log->bios_event_log) > return -ENOMEM; > > -- > 2.17.1 > This is a really great catch! I'm a bit late of my PR a bit because of SGX upstreaming madness (sending v39 soon). If you can answer to my question above, I can do that nitpick change to patch and get it to my v5.10 PR. PS. Just so that you know, once I've applied it, it will be available here: git://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git I'll include MAINTAINERS update to that PR. /Jarkko
