[PATCH 1/2] asm-generic: current: Don't include thread-info.h if building asm

[PATCH 1/2] asm-generic: current: Don't include thread-info.h if building asm

[David Gow]

asm/current.h is included by some assembly files (either directly, or
indirectly). This works on some architectures (such as x86), as their
implementation of current.h is careful to not include any C, but the
asm-generic version includes linux/thread-info.h unconditionally, which
leads to errors when either C code or non-asm-compatible preprocessor
directives are included.

Just wrap the contents behind an #ifndef __ASSEMBLY__ to avoid any C
code making its way in.

Signed-off-by: David Gow <davidgow@google.com>
---

This is requrired for patch #2 here, as UML uses this asm-generic
header, but works with x86 assembly files which are expecting the x86
current.h, which is assembly-friendly.

---
 include/asm-generic/current.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/asm-generic/current.h b/include/asm-generic/current.h
index 3a2e224b9fa0..9c2aeecbd05a 100644
--- a/include/asm-generic/current.h
+++ b/include/asm-generic/current.h
@@ -2,9 +2,11 @@
 #ifndef __ASM_GENERIC_CURRENT_H
 #define __ASM_GENERIC_CURRENT_H
 
+#ifndef __ASSEMBLY__
 #include <linux/thread_info.h>
 
 #define get_current() (current_thread_info()->task)
 #define current get_current()
+#endif
 
 #endif /* __ASM_GENERIC_CURRENT_H */
-- 
2.41.0.255.g8b1d071c50-goog


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[PATCH 2/2] arch: um: Use the x86 checksum implementation on 32-bit

[David Gow]

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checksum_32.S, which is terribly out-of-date and doesn't support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@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@laser.satlink.net>
- *		Arnt Gulbrandsen, <agulbra@nvg.unit.no>
- *		Tom May, <ftom@netcom.com>
- *              Pentium Pro/II routines:
- *              Alexander Kjeldaas <astor@guardian.no>
- *              Finn Arne Gangstad <finnag@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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Re: [PATCH 1/2] asm-generic: current: Don't include thread-info.h if building asm

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "davidgow" <davidgow@google.com>
> asm/current.h is included by some assembly files (either directly, or
> indirectly). This works on some architectures (such as x86), as their
> implementation of current.h is careful to not include any C, but the
> asm-generic version includes linux/thread-info.h unconditionally, which
> leads to errors when either C code or non-asm-compatible preprocessor
> directives are included.
> 
> Just wrap the contents behind an #ifndef __ASSEMBLY__ to avoid any C
> code making its way in.
> 
> Signed-off-by: David Gow <davidgow@google.com>
> ---
> 
> This is requrired for patch #2 here, as UML uses this asm-generic
> header, but works with x86 assembly files which are expecting the x86
> current.h, which is assembly-friendly.
> 
> ---
> include/asm-generic/current.h | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/include/asm-generic/current.h b/include/asm-generic/current.h
> index 3a2e224b9fa0..9c2aeecbd05a 100644
> --- a/include/asm-generic/current.h
> +++ b/include/asm-generic/current.h
> @@ -2,9 +2,11 @@
> #ifndef __ASM_GENERIC_CURRENT_H
> #define __ASM_GENERIC_CURRENT_H
> 
> +#ifndef __ASSEMBLY__
> #include <linux/thread_info.h>
> 
> #define get_current() (current_thread_info()->task)
> #define current get_current()
> +#endif
> 
> #endif /* __ASM_GENERIC_CURRENT_H */

I'm fine with the UML side of this change but the generic part needs Arnd's ACK.

Thanks,
//richard

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Re: [PATCH 1/2] asm-generic: current: Don't include thread-info.h if building asm

[Arnd Bergmann]

On Tue, Jul 4, 2023, at 04:30, David Gow wrote:
> asm/current.h is included by some assembly files (either directly, or
> indirectly). This works on some architectures (such as x86), as their
> implementation of current.h is careful to not include any C, but the
> asm-generic version includes linux/thread-info.h unconditionally, which
> leads to errors when either C code or non-asm-compatible preprocessor
> directives are included.
>
> Just wrap the contents behind an #ifndef __ASSEMBLY__ to avoid any C
> code making its way in.
>
> Signed-off-by: David Gow <davidgow@google.com>

Acked-by: Arnd Bergmann <arnd@arndb.de>

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