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f2d57765b7
The use of kmap() is being deprecated in favor of kmap_local_page(). Two main problems with kmap(): (1) It comes with an overhead as mapping space is restricted and protected by a global lock for synchronization and (2) kmap() also requires global TLB invalidation when the kmap’s pool wraps and it might block when the mapping space is fully utilized until a slot becomes available. kmap_local_page() is preferred over kmap() and kmap_atomic(). Where it cannot mechanically replace the latters, code refactor should be considered (special care must be taken if kernel virtual addresses are aliases in different contexts). With kmap_local_page() the mappings are per thread, CPU local, can take page faults, and can be called from any context (including interrupts). Call kmap_local_page() in firmware_loader wherever kmap() is currently used. In firmware_rw() use the helpers copy_{from,to}_page() instead of open coding the local mappings + memcpy(). Successfully tested with "firmware" selftests on a QEMU/KVM 32-bits VM with 4GB RAM, booting a kernel with HIGHMEM64GB enabled. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Suggested-by: Ira Weiny <ira.weiny@intel.com> Reviewed-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Link: https://lore.kernel.org/r/20220714235030.12732-1-fmdefrancesco@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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.. | ||
firmware_loader | ||
power | ||
regmap | ||
test | ||
arch_numa.c | ||
arch_topology.c | ||
attribute_container.c | ||
auxiliary.c | ||
base.h | ||
bus.c | ||
cacheinfo.c | ||
class.c | ||
component.c | ||
container.c | ||
core.c | ||
cpu.c | ||
dd.c | ||
devcoredump.c | ||
devres.c | ||
devtmpfs.c | ||
driver.c | ||
firmware.c | ||
hypervisor.c | ||
init.c | ||
isa.c | ||
Kconfig | ||
Makefile | ||
map.c | ||
memory.c | ||
module.c | ||
node.c | ||
physical_location.c | ||
physical_location.h | ||
pinctrl.c | ||
platform-msi.c | ||
platform.c | ||
property.c | ||
soc.c | ||
swnode.c | ||
syscore.c | ||
topology.c | ||
trace.c | ||
trace.h | ||
transport_class.c |