Merge patch series "riscv: Add fine-tuned checksum functions"

Charlie Jenkins <charlie@rivosinc.com> says:

Each architecture generally implements fine-tuned checksum functions to
leverage the instruction set. This patch adds the main checksum
functions that are used in networking. Tested on QEMU, this series
allows the CHECKSUM_KUNIT tests to complete an average of 50.9% faster.

This patch takes heavy use of the Zbb extension using alternatives
patching.

To test this patch, enable the configs for KUNIT, then CHECKSUM_KUNIT.

I have attempted to make these functions as optimal as possible, but I
have not ran anything on actual riscv hardware. My performance testing
has been limited to inspecting the assembly, running the algorithms on
x86 hardware, and running in QEMU.

ip_fast_csum is a relatively small function so even though it is
possible to read 64 bits at a time on compatible hardware, the
bottleneck becomes the clean up and setup code so loading 32 bits at a
time is actually faster.

* b4-shazam-merge:
  kunit: Add tests for csum_ipv6_magic and ip_fast_csum
  riscv: Add checksum library
  riscv: Add checksum header
  riscv: Add static key for misaligned accesses
  asm-generic: Improve csum_fold

Link: https://lore.kernel.org/r/20240108-optimize_checksum-v15-0-1c50de5f2167@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --cc arch/riscv/include/asm/cpufeature.h
Simple merge

diff --cc arch/riscv/kernel/cpufeature.c
Simple merge

diff --cc arch/riscv/lib/Makefile
index c8a6787,2aa1a4a..bd6e6c1
--- 1/arch/riscv/lib/Makefile
--- 2/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@@ -6,10 -6,8 +6,11 @@@ lib-y                  += memmove.
  lib-y                 += strcmp.o
  lib-y                 += strlen.o
  lib-y                 += strncmp.o
- lib-y                         += uaccess.o
+ lib-y                 += csum.o
 +ifeq ($(CONFIG_MMU), y)
 +lib-$(CONFIG_RISCV_ISA_V)     += uaccess_vector.o
 +endif
+ lib-$(CONFIG_MMU)     += uaccess.o
  lib-$(CONFIG_64BIT)   += tishift.o
  lib-$(CONFIG_RISCV_ISA_ZICBOZ)        += clear_page.o