netdev - Re: [PATCH v4 binutils] Add BPF support to binutils...

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Date:   Fri, 5 May 2017 11:24:19 -0700
From:   Alexei Starovoitov <ast@...com>
To:     David Miller <davem@...emloft.net>
CC:     <daniel@...earbox.net>, <netdev@...r.kernel.org>,
        <xdp-newbies@...r.kernel.org>, Yonghong Song <yhs@...com>
Subject: Re: [PATCH v4 binutils] Add BPF support to binutils...

On 5/1/17 8:49 PM, Alexei Starovoitov wrote:
> On 4/30/17 9:07 AM, David Miller wrote:
>> This is mainly a synchronization point, I still need to look
>> more deeply into Alexei's -g issue.
>>
>> New in this version from v3:
>>  - Remove tailcall from opcode table
>>  - Rearrange relocations so that numbers match with LLVM ones
>>  - Emit relocs properly so that dwarf2 debug info tests pass
>>  - Handle negative load/store offsets properly, add tests
>>
>> Signed-off-by: David S. Miller <davem@...emloft.net>
>
> dwarf on little endian works now :)

Yonghong fixed llvm bug with big-endian dwarf [1]
and binutils worked out of the box :)

$ ./bin/clang -O2 -target bpfeb -c -g test.c
$ /w/binutils-gdb/bld/binutils/objdump -S test.o

test.o:     file format elf64-bpfbe

Disassembly of section .text:
0000000000000000 <bpf_prog1>:
int bpf_prog1(void *ign)
{
   volatile unsigned long t = 0x8983984739ull;
    0:	18 10 00 00 83 98 47 39 	ldimm64	r1, 590618314553
    8:	00 00 00 00 00 00 00 89
   10:	7b a1 ff f8 00 00 00 00 	stdw	[r10+-8], r1
   return *(unsigned long *)((0xffffffff8fff0002ull) + t);
   18:	79 1a ff f8 00 00 00 00 	lddw	r1, [r10+-8]

[1]
https://reviews.llvm.org/rL302265