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131484c8da
So the dwarf2 annotations in low level assembly code have become an increasing hindrance: unreadable, messy macros mixed into some of the most security sensitive code paths of the Linux kernel. These debug info annotations don't even buy the upstream kernel anything: dwarf driven stack unwinding has caused problems in the past so it's out of tree, and the upstream kernel only uses the much more robust framepointers based stack unwinding method. In addition to that there's a steady, slow bitrot going on with these annotations, requiring frequent fixups. There's no tooling and no functionality upstream that keeps it correct. So burn down the sick forest, allowing new, healthier growth: 27 files changed, 350 insertions(+), 1101 deletions(-) Someone who has the willingness and time to do this properly can attempt to reintroduce dwarf debuginfo in x86 assembly code plus dwarf unwinding from first principles, with the following conditions: - it should be maximally readable, and maximally low-key to 'ordinary' code reading and maintenance. - find a build time method to insert dwarf annotations automatically in the most common cases, for pop/push instructions that manipulate the stack pointer. This could be done for example via a preprocessing step that just looks for common patterns - plus special annotations for the few cases where we want to depart from the default. We have hundreds of CFI annotations, so automating most of that makes sense. - it should come with build tooling checks that ensure that CFI annotations are sensible. We've seen such efforts from the framepointer side, and there's no reason it couldn't be done on the dwarf side. Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frédéric Weisbecker <fweisbec@gmail.com Cc: H. Peter Anvin <hpa@zytor.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
493 lines
10 KiB
ArmAsm
493 lines
10 KiB
ArmAsm
/*
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* INET An implementation of the TCP/IP protocol suite for the LINUX
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* operating system. INET is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* IP/TCP/UDP checksumming routines
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*
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* Authors: Jorge Cwik, <jorge@laser.satlink.net>
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* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
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* Tom May, <ftom@netcom.com>
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* Pentium Pro/II routines:
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* Alexander Kjeldaas <astor@guardian.no>
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* Finn Arne Gangstad <finnag@guardian.no>
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* Lots of code moved from tcp.c and ip.c; see those files
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* for more names.
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*
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* Changes: Ingo Molnar, converted csum_partial_copy() to 2.1 exception
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* handling.
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* Andi Kleen, add zeroing on error
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* converted to pure assembler
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/linkage.h>
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#include <asm/errno.h>
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#include <asm/asm.h>
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/*
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* computes a partial checksum, e.g. for TCP/UDP fragments
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*/
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/*
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unsigned int csum_partial(const unsigned char * buff, int len, unsigned int sum)
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*/
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.text
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#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
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/*
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* Experiments with Ethernet and SLIP connections show that buff
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* is aligned on either a 2-byte or 4-byte boundary. We get at
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* least a twofold speedup on 486 and Pentium if it is 4-byte aligned.
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* Fortunately, it is easy to convert 2-byte alignment to 4-byte
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* alignment for the unrolled loop.
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*/
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ENTRY(csum_partial)
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pushl %esi
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pushl %ebx
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movl 20(%esp),%eax # Function arg: unsigned int sum
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movl 16(%esp),%ecx # Function arg: int len
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movl 12(%esp),%esi # Function arg: unsigned char *buff
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testl $3, %esi # Check alignment.
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jz 2f # Jump if alignment is ok.
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testl $1, %esi # Check alignment.
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jz 10f # Jump if alignment is boundary of 2 bytes.
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# buf is odd
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dec %ecx
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jl 8f
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movzbl (%esi), %ebx
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adcl %ebx, %eax
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roll $8, %eax
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inc %esi
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testl $2, %esi
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jz 2f
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10:
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subl $2, %ecx # Alignment uses up two bytes.
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jae 1f # Jump if we had at least two bytes.
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addl $2, %ecx # ecx was < 2. Deal with it.
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jmp 4f
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1: movw (%esi), %bx
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addl $2, %esi
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addw %bx, %ax
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adcl $0, %eax
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2:
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movl %ecx, %edx
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shrl $5, %ecx
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jz 2f
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testl %esi, %esi
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1: movl (%esi), %ebx
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adcl %ebx, %eax
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movl 4(%esi), %ebx
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adcl %ebx, %eax
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movl 8(%esi), %ebx
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adcl %ebx, %eax
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movl 12(%esi), %ebx
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adcl %ebx, %eax
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movl 16(%esi), %ebx
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adcl %ebx, %eax
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movl 20(%esi), %ebx
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adcl %ebx, %eax
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movl 24(%esi), %ebx
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adcl %ebx, %eax
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movl 28(%esi), %ebx
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adcl %ebx, %eax
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lea 32(%esi), %esi
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dec %ecx
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jne 1b
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adcl $0, %eax
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2: movl %edx, %ecx
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andl $0x1c, %edx
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je 4f
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shrl $2, %edx # This clears CF
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3: adcl (%esi), %eax
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lea 4(%esi), %esi
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dec %edx
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jne 3b
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adcl $0, %eax
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4: andl $3, %ecx
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jz 7f
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cmpl $2, %ecx
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jb 5f
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movw (%esi),%cx
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leal 2(%esi),%esi
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je 6f
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shll $16,%ecx
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5: movb (%esi),%cl
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6: addl %ecx,%eax
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adcl $0, %eax
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7:
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testb $1, 12(%esp)
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jz 8f
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roll $8, %eax
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8:
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popl %ebx
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popl %esi
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ret
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ENDPROC(csum_partial)
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#else
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/* Version for PentiumII/PPro */
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ENTRY(csum_partial)
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pushl %esi
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pushl %ebx
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movl 20(%esp),%eax # Function arg: unsigned int sum
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movl 16(%esp),%ecx # Function arg: int len
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movl 12(%esp),%esi # Function arg: const unsigned char *buf
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testl $3, %esi
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jnz 25f
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10:
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movl %ecx, %edx
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movl %ecx, %ebx
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andl $0x7c, %ebx
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shrl $7, %ecx
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addl %ebx,%esi
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shrl $2, %ebx
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negl %ebx
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lea 45f(%ebx,%ebx,2), %ebx
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testl %esi, %esi
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jmp *%ebx
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# Handle 2-byte-aligned regions
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20: addw (%esi), %ax
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lea 2(%esi), %esi
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adcl $0, %eax
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jmp 10b
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25:
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testl $1, %esi
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jz 30f
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# buf is odd
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dec %ecx
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jl 90f
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movzbl (%esi), %ebx
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addl %ebx, %eax
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adcl $0, %eax
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roll $8, %eax
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inc %esi
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testl $2, %esi
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jz 10b
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30: subl $2, %ecx
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ja 20b
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je 32f
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addl $2, %ecx
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jz 80f
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movzbl (%esi),%ebx # csumming 1 byte, 2-aligned
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addl %ebx, %eax
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adcl $0, %eax
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jmp 80f
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32:
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addw (%esi), %ax # csumming 2 bytes, 2-aligned
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adcl $0, %eax
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jmp 80f
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40:
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addl -128(%esi), %eax
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adcl -124(%esi), %eax
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adcl -120(%esi), %eax
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adcl -116(%esi), %eax
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adcl -112(%esi), %eax
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adcl -108(%esi), %eax
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adcl -104(%esi), %eax
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adcl -100(%esi), %eax
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adcl -96(%esi), %eax
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adcl -92(%esi), %eax
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adcl -88(%esi), %eax
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adcl -84(%esi), %eax
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adcl -80(%esi), %eax
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adcl -76(%esi), %eax
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adcl -72(%esi), %eax
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adcl -68(%esi), %eax
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adcl -64(%esi), %eax
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adcl -60(%esi), %eax
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adcl -56(%esi), %eax
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adcl -52(%esi), %eax
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adcl -48(%esi), %eax
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adcl -44(%esi), %eax
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adcl -40(%esi), %eax
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adcl -36(%esi), %eax
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adcl -32(%esi), %eax
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adcl -28(%esi), %eax
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adcl -24(%esi), %eax
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adcl -20(%esi), %eax
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adcl -16(%esi), %eax
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adcl -12(%esi), %eax
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adcl -8(%esi), %eax
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adcl -4(%esi), %eax
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45:
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lea 128(%esi), %esi
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adcl $0, %eax
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dec %ecx
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jge 40b
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movl %edx, %ecx
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50: andl $3, %ecx
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jz 80f
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# Handle the last 1-3 bytes without jumping
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notl %ecx # 1->2, 2->1, 3->0, higher bits are masked
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movl $0xffffff,%ebx # by the shll and shrl instructions
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shll $3,%ecx
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shrl %cl,%ebx
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andl -128(%esi),%ebx # esi is 4-aligned so should be ok
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addl %ebx,%eax
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adcl $0,%eax
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80:
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testb $1, 12(%esp)
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jz 90f
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roll $8, %eax
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90:
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popl %ebx
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popl %esi
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ret
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ENDPROC(csum_partial)
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#endif
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/*
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unsigned int csum_partial_copy_generic (const char *src, char *dst,
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int len, int sum, int *src_err_ptr, int *dst_err_ptr)
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*/
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/*
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* Copy from ds while checksumming, otherwise like csum_partial
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*
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* The macros SRC and DST specify the type of access for the instruction.
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* thus we can call a custom exception handler for all access types.
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*
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* FIXME: could someone double-check whether I haven't mixed up some SRC and
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* DST definitions? It's damn hard to trigger all cases. I hope I got
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* them all but there's no guarantee.
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*/
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#define SRC(y...) \
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9999: y; \
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_ASM_EXTABLE(9999b, 6001f)
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#define DST(y...) \
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9999: y; \
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_ASM_EXTABLE(9999b, 6002f)
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#ifndef CONFIG_X86_USE_PPRO_CHECKSUM
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#define ARGBASE 16
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#define FP 12
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ENTRY(csum_partial_copy_generic)
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subl $4,%esp
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pushl %edi
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pushl %esi
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pushl %ebx
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movl ARGBASE+16(%esp),%eax # sum
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movl ARGBASE+12(%esp),%ecx # len
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movl ARGBASE+4(%esp),%esi # src
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movl ARGBASE+8(%esp),%edi # dst
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testl $2, %edi # Check alignment.
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jz 2f # Jump if alignment is ok.
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subl $2, %ecx # Alignment uses up two bytes.
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jae 1f # Jump if we had at least two bytes.
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addl $2, %ecx # ecx was < 2. Deal with it.
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jmp 4f
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SRC(1: movw (%esi), %bx )
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addl $2, %esi
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DST( movw %bx, (%edi) )
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addl $2, %edi
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addw %bx, %ax
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adcl $0, %eax
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2:
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movl %ecx, FP(%esp)
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shrl $5, %ecx
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jz 2f
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testl %esi, %esi
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SRC(1: movl (%esi), %ebx )
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SRC( movl 4(%esi), %edx )
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adcl %ebx, %eax
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DST( movl %ebx, (%edi) )
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adcl %edx, %eax
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DST( movl %edx, 4(%edi) )
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SRC( movl 8(%esi), %ebx )
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SRC( movl 12(%esi), %edx )
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adcl %ebx, %eax
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DST( movl %ebx, 8(%edi) )
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adcl %edx, %eax
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DST( movl %edx, 12(%edi) )
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SRC( movl 16(%esi), %ebx )
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SRC( movl 20(%esi), %edx )
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adcl %ebx, %eax
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DST( movl %ebx, 16(%edi) )
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adcl %edx, %eax
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DST( movl %edx, 20(%edi) )
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SRC( movl 24(%esi), %ebx )
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SRC( movl 28(%esi), %edx )
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adcl %ebx, %eax
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DST( movl %ebx, 24(%edi) )
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adcl %edx, %eax
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DST( movl %edx, 28(%edi) )
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lea 32(%esi), %esi
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lea 32(%edi), %edi
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dec %ecx
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jne 1b
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adcl $0, %eax
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2: movl FP(%esp), %edx
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movl %edx, %ecx
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andl $0x1c, %edx
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je 4f
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shrl $2, %edx # This clears CF
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SRC(3: movl (%esi), %ebx )
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adcl %ebx, %eax
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DST( movl %ebx, (%edi) )
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lea 4(%esi), %esi
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lea 4(%edi), %edi
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dec %edx
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jne 3b
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adcl $0, %eax
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4: andl $3, %ecx
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jz 7f
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cmpl $2, %ecx
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jb 5f
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SRC( movw (%esi), %cx )
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leal 2(%esi), %esi
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DST( movw %cx, (%edi) )
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leal 2(%edi), %edi
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je 6f
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shll $16,%ecx
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SRC(5: movb (%esi), %cl )
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DST( movb %cl, (%edi) )
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6: addl %ecx, %eax
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adcl $0, %eax
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7:
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5000:
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# Exception handler:
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.section .fixup, "ax"
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6001:
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movl ARGBASE+20(%esp), %ebx # src_err_ptr
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movl $-EFAULT, (%ebx)
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# zero the complete destination - computing the rest
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# is too much work
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movl ARGBASE+8(%esp), %edi # dst
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movl ARGBASE+12(%esp), %ecx # len
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xorl %eax,%eax
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rep ; stosb
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jmp 5000b
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6002:
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movl ARGBASE+24(%esp), %ebx # dst_err_ptr
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movl $-EFAULT,(%ebx)
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jmp 5000b
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.previous
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popl %ebx
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popl %esi
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popl %edi
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popl %ecx # equivalent to addl $4,%esp
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ret
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ENDPROC(csum_partial_copy_generic)
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#else
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/* Version for PentiumII/PPro */
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#define ROUND1(x) \
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SRC(movl x(%esi), %ebx ) ; \
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addl %ebx, %eax ; \
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DST(movl %ebx, x(%edi) ) ;
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#define ROUND(x) \
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SRC(movl x(%esi), %ebx ) ; \
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adcl %ebx, %eax ; \
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DST(movl %ebx, x(%edi) ) ;
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#define ARGBASE 12
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ENTRY(csum_partial_copy_generic)
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pushl %ebx
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pushl %edi
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pushl %esi
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movl ARGBASE+4(%esp),%esi #src
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movl ARGBASE+8(%esp),%edi #dst
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movl ARGBASE+12(%esp),%ecx #len
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movl ARGBASE+16(%esp),%eax #sum
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# movl %ecx, %edx
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movl %ecx, %ebx
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movl %esi, %edx
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shrl $6, %ecx
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andl $0x3c, %ebx
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negl %ebx
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subl %ebx, %esi
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subl %ebx, %edi
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lea -1(%esi),%edx
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andl $-32,%edx
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lea 3f(%ebx,%ebx), %ebx
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testl %esi, %esi
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jmp *%ebx
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1: addl $64,%esi
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addl $64,%edi
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SRC(movb -32(%edx),%bl) ; SRC(movb (%edx),%bl)
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ROUND1(-64) ROUND(-60) ROUND(-56) ROUND(-52)
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ROUND (-48) ROUND(-44) ROUND(-40) ROUND(-36)
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ROUND (-32) ROUND(-28) ROUND(-24) ROUND(-20)
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ROUND (-16) ROUND(-12) ROUND(-8) ROUND(-4)
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3: adcl $0,%eax
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addl $64, %edx
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dec %ecx
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jge 1b
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4: movl ARGBASE+12(%esp),%edx #len
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andl $3, %edx
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jz 7f
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cmpl $2, %edx
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jb 5f
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SRC( movw (%esi), %dx )
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leal 2(%esi), %esi
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DST( movw %dx, (%edi) )
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leal 2(%edi), %edi
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je 6f
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shll $16,%edx
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5:
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SRC( movb (%esi), %dl )
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DST( movb %dl, (%edi) )
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6: addl %edx, %eax
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adcl $0, %eax
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7:
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.section .fixup, "ax"
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6001: movl ARGBASE+20(%esp), %ebx # src_err_ptr
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movl $-EFAULT, (%ebx)
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# zero the complete destination (computing the rest is too much work)
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movl ARGBASE+8(%esp),%edi # dst
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movl ARGBASE+12(%esp),%ecx # len
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xorl %eax,%eax
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rep; stosb
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jmp 7b
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6002: movl ARGBASE+24(%esp), %ebx # dst_err_ptr
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movl $-EFAULT, (%ebx)
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jmp 7b
|
|
.previous
|
|
|
|
popl %esi
|
|
popl %edi
|
|
popl %ebx
|
|
ret
|
|
ENDPROC(csum_partial_copy_generic)
|
|
|
|
#undef ROUND
|
|
#undef ROUND1
|
|
|
|
#endif
|