[PATCH 2/2] arch: um: Use the x86 checksum implementation on 32-bit
David Gow
davidgow at google.com
Tue Jul 4 01:30:22 PDT 2023
When UML is compiled under 32-bit x86, it uses its own copy of
checksum_32.S, which is terribly out-of-date and doesn't support
checksumming unaligned data.
This causes the new "checksum" KUnit test to fail:
./tools/testing/kunit/kunit.py run --kconfig_add CONFIG_64BIT=n --cross_compile i686-linux-gnu- checksum
KTAP version 1
# Subtest: checksum
1..3
# test_csum_fixed_random_inputs: ASSERTION FAILED at lib/checksum_kunit.c:243
Expected result == expec, but
result == 33316 (0x8224)
expec == 33488 (0x82d0)
not ok 1 test_csum_fixed_random_inputs
# test_csum_all_carry_inputs: ASSERTION FAILED at lib/checksum_kunit.c:267
Expected result == expec, but
result == 65280 (0xff00)
expec == 0 (0x0)
not ok 2 test_csum_all_carry_inputs
# test_csum_no_carry_inputs: ASSERTION FAILED at lib/checksum_kunit.c:306
Expected result == expec, but
result == 65531 (0xfffb)
expec == 0 (0x0)
not ok 3 test_csum_no_carry_inputs
Sharing the normal implementation in arch/x86/lib both fixes all of
these issues and means any further fixes only need to be done once.
x86_64 already seems to share the same implementation between UML and
"normal" x86.
Signed-off-by: David Gow <davidgow at google.com>
---
Note that there is a further issue with the pre-pentium-pro codepath in
the shared x86 code, which I'll send a separate fix out for. i686+ works
fine with just this series.
---
arch/x86/um/Makefile | 3 +-
arch/x86/um/checksum_32.S | 214 --------------------------------------
2 files changed, 2 insertions(+), 215 deletions(-)
delete mode 100644 arch/x86/um/checksum_32.S
diff --git a/arch/x86/um/Makefile b/arch/x86/um/Makefile
index ee89f6bb9242..cb738967a9f5 100644
--- a/arch/x86/um/Makefile
+++ b/arch/x86/um/Makefile
@@ -17,11 +17,12 @@ obj-y = bugs_$(BITS).o delay.o fault.o ldt.o \
ifeq ($(CONFIG_X86_32),y)
-obj-y += checksum_32.o syscalls_32.o
+obj-y += syscalls_32.o
obj-$(CONFIG_ELF_CORE) += elfcore.o
subarch-y = ../lib/string_32.o ../lib/atomic64_32.o ../lib/atomic64_cx8_32.o
subarch-y += ../lib/cmpxchg8b_emu.o ../lib/atomic64_386_32.o
+subarch-y += ../lib/checksum_32.o
subarch-y += ../kernel/sys_ia32.o
else
diff --git a/arch/x86/um/checksum_32.S b/arch/x86/um/checksum_32.S
deleted file mode 100644
index aed782ab7721..000000000000
--- a/arch/x86/um/checksum_32.S
+++ /dev/null
@@ -1,214 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
-/*
- * INET An implementation of the TCP/IP protocol suite for the LINUX
- * operating system. INET is implemented using the BSD Socket
- * interface as the means of communication with the user level.
- *
- * IP/TCP/UDP checksumming routines
- *
- * Authors: Jorge Cwik, <jorge at laser.satlink.net>
- * Arnt Gulbrandsen, <agulbra at nvg.unit.no>
- * Tom May, <ftom at netcom.com>
- * Pentium Pro/II routines:
- * Alexander Kjeldaas <astor at guardian.no>
- * Finn Arne Gangstad <finnag at guardian.no>
- * Lots of code moved from tcp.c and ip.c; see those files
- * for more names.
- *
- * Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
- * handling.
- * Andi Kleen, add zeroing on error
- * converted to pure assembler
- */
-
-#include <asm/errno.h>
-#include <asm/asm.h>
-#include <asm/export.h>
-
-/*
- * computes a partial checksum, e.g. for TCP/UDP fragments
- */
-
-/*
-unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
- */
-
-.text
-.align 4
-.globl csum_partial
-
-#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
-
- /*
- * Experiments with Ethernet and SLIP connections show that buff
- * is aligned on either a 2-byte or 4-byte boundary. We get at
- * least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
- * Fortunately, it is easy to convert 2-byte alignment to 4-byte
- * alignment for the unrolled loop.
- */
-csum_partial:
- pushl %esi
- pushl %ebx
- movl 20(%esp),%eax # Function arg: unsigned int sum
- movl 16(%esp),%ecx # Function arg: int len
- movl 12(%esp),%esi # Function arg: unsigned char *buff
- testl $2, %esi # Check alignment.
- jz 2f # Jump if alignment is ok.
- subl $2, %ecx # Alignment uses up two bytes.
- jae 1f # Jump if we had at least two bytes.
- addl $2, %ecx # ecx was < 2. Deal with it.
- jmp 4f
-1: movw (%esi), %bx
- addl $2, %esi
- addw %bx, %ax
- adcl $0, %eax
-2:
- movl %ecx, %edx
- shrl $5, %ecx
- jz 2f
- testl %esi, %esi
-1: movl (%esi), %ebx
- adcl %ebx, %eax
- movl 4(%esi), %ebx
- adcl %ebx, %eax
- movl 8(%esi), %ebx
- adcl %ebx, %eax
- movl 12(%esi), %ebx
- adcl %ebx, %eax
- movl 16(%esi), %ebx
- adcl %ebx, %eax
- movl 20(%esi), %ebx
- adcl %ebx, %eax
- movl 24(%esi), %ebx
- adcl %ebx, %eax
- movl 28(%esi), %ebx
- adcl %ebx, %eax
- lea 32(%esi), %esi
- dec %ecx
- jne 1b
- adcl $0, %eax
-2: movl %edx, %ecx
- andl $0x1c, %edx
- je 4f
- shrl $2, %edx # This clears CF
-3: adcl (%esi), %eax
- lea 4(%esi), %esi
- dec %edx
- jne 3b
- adcl $0, %eax
-4: andl $3, %ecx
- jz 7f
- cmpl $2, %ecx
- jb 5f
- movw (%esi),%cx
- leal 2(%esi),%esi
- je 6f
- shll $16,%ecx
-5: movb (%esi),%cl
-6: addl %ecx,%eax
- adcl $0, %eax
-7:
- popl %ebx
- popl %esi
- RET
-
-#else
-
-/* Version for PentiumII/PPro */
-
-csum_partial:
- pushl %esi
- pushl %ebx
- movl 20(%esp),%eax # Function arg: unsigned int sum
- movl 16(%esp),%ecx # Function arg: int len
- movl 12(%esp),%esi # Function arg: const unsigned char *buf
-
- testl $2, %esi
- jnz 30f
-10:
- movl %ecx, %edx
- movl %ecx, %ebx
- andl $0x7c, %ebx
- shrl $7, %ecx
- addl %ebx,%esi
- shrl $2, %ebx
- negl %ebx
- lea 45f(%ebx,%ebx,2), %ebx
- testl %esi, %esi
- jmp *%ebx
-
- # Handle 2-byte-aligned regions
-20: addw (%esi), %ax
- lea 2(%esi), %esi
- adcl $0, %eax
- jmp 10b
-
-30: subl $2, %ecx
- ja 20b
- je 32f
- movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
- addl %ebx, %eax
- adcl $0, %eax
- jmp 80f
-32:
- addw (%esi), %ax # csumming 2 bytes, 2-aligned
- adcl $0, %eax
- jmp 80f
-
-40:
- addl -128(%esi), %eax
- adcl -124(%esi), %eax
- adcl -120(%esi), %eax
- adcl -116(%esi), %eax
- adcl -112(%esi), %eax
- adcl -108(%esi), %eax
- adcl -104(%esi), %eax
- adcl -100(%esi), %eax
- adcl -96(%esi), %eax
- adcl -92(%esi), %eax
- adcl -88(%esi), %eax
- adcl -84(%esi), %eax
- adcl -80(%esi), %eax
- adcl -76(%esi), %eax
- adcl -72(%esi), %eax
- adcl -68(%esi), %eax
- adcl -64(%esi), %eax
- adcl -60(%esi), %eax
- adcl -56(%esi), %eax
- adcl -52(%esi), %eax
- adcl -48(%esi), %eax
- adcl -44(%esi), %eax
- adcl -40(%esi), %eax
- adcl -36(%esi), %eax
- adcl -32(%esi), %eax
- adcl -28(%esi), %eax
- adcl -24(%esi), %eax
- adcl -20(%esi), %eax
- adcl -16(%esi), %eax
- adcl -12(%esi), %eax
- adcl -8(%esi), %eax
- adcl -4(%esi), %eax
-45:
- lea 128(%esi), %esi
- adcl $0, %eax
- dec %ecx
- jge 40b
- movl %edx, %ecx
-50: andl $3, %ecx
- jz 80f
-
- # Handle the last 1-3 bytes without jumping
- notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
- movl $0xffffff,%ebx # by the shll and shrl instructions
- shll $3,%ecx
- shrl %cl,%ebx
- andl -128(%esi),%ebx # esi is 4-aligned so should be ok
- addl %ebx,%eax
- adcl $0,%eax
-80:
- popl %ebx
- popl %esi
- RET
-
-#endif
- EXPORT_SYMBOL(csum_partial)
--
2.41.0.255.g8b1d071c50-goog
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