Fixed MTP to work with TWRP

arch/x86/um/checksum_32.S

@@ -0,0 +1,216 @@
+/*
+ * 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
+ *
+ *		This program is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU General Public License
+ *		as published by the Free Software Foundation; either version
+ *		2 of the License, or (at your option) any later version.
+ */
+
+#include <asm/errno.h>
+#include <asm/asm.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