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From: Will Hawkins <hawkinsw@obs.cr>
To: "Jose E. Marchesi" <jose.marchesi@oracle.com>
Cc: binutils@sourceware.org, yonghong.song@linux.dev
Subject: Re: [PATCH v3 1/1] objdump, as: Add callx support for BPF CPU v1
Date: Wed, 14 Feb 2024 17:13:36 -0500	[thread overview]
Message-ID: <CADx9qWhzTC-HfxB0zCz_DfH952xRGZMgVogpjkFwm-Op9oo_ow@mail.gmail.com> (raw)
In-Reply-To: <CADx9qWgQ2m0w=nnQrsur2PH3hy=Ooc-KgTq1uKtK+t-+CC+c0w@mail.gmail.com>

On Wed, Feb 14, 2024 at 11:36 AM Will Hawkins <hawkinsw@obs.cr> wrote:
>
> On Wed, Feb 14, 2024 at 11:30 AM Jose E. Marchesi
> <jose.marchesi@oracle.com> wrote:
> >
> >
> > Hi Will.
> > Thanks for the patch.  Please see some comments below.
> >
> > > Add support for (dis)assembling the callx instruction back to CPU v1.
> > >
> > > gas/ChangeLog:
> > >
> > >       * testsuite/gas/bpf/indcall-1-pseudoc.d: Refactor tests ...
> > >       * testsuite/gas/bpf/indcall-1-pseudoc.s: ... to visually match ...
> > >       * testsuite/gas/bpf/indcall-1.d: ... equivalent test in ...
> > >       * testsuite/gas/bpf/indcall-1.s: ... clang/llvm.
> > >
> > > include/ChangeLog:
> > >
> > >       * opcode/bpf.h (enum bpf_insn_id): BPF_INSN_CALLR to BPF_INSN_CALLX
> > >       * (for consistency) and add it to the v1 ISA variant.
> > >
> > > opcodes/ChangeLog:
> > >
> > >       * bpf-opc.c: Use BPF_INSN_CALLX instead of BPF_INSN_CALLR.
> > >
> > > Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
> > > ---
> > >  gas/testsuite/gas/bpf/indcall-1-pseudoc.d |  8 ++++----
> > >  gas/testsuite/gas/bpf/indcall-1-pseudoc.s |  6 +++---
> > >  gas/testsuite/gas/bpf/indcall-1.d         | 10 +++++-----
> > >  gas/testsuite/gas/bpf/indcall-1.s         |  6 +++---
> > >  include/opcode/bpf.h                      |  2 +-
> > >  opcodes/bpf-opc.c                         |  4 ++--
> > >  6 files changed, 18 insertions(+), 18 deletions(-)
> > >
> > > diff --git a/gas/testsuite/gas/bpf/indcall-1-pseudoc.d b/gas/testsuite/gas/bpf/indcall-1-pseudoc.d
> > > index 7a95bad8e65..12f9d6a9d49 100644
> > > --- a/gas/testsuite/gas/bpf/indcall-1-pseudoc.d
> > > +++ b/gas/testsuite/gas/bpf/indcall-1-pseudoc.d
> > > @@ -1,4 +1,4 @@
> > > -#as: -EL -mdialect=pseudoc -misa-spec=xbpf
> > > +#as: -EL -mdialect=pseudoc -misa-spec=v1
> >
> > I think this test can now omit -misa-spec entirely.
> >
> > >  #objdump: -M xbpf,pseudoc,dec -dr
> > >  #source: indcall-1-pseudoc.s
> > >  #name: BPF indirect call 1, pseudoc syntax
> > > @@ -10,11 +10,11 @@ Disassembly of section \.text:
> > >  0000000000000000 <main>:
> > >     0:        b7 00 00 00 01 00 00 00         r0=1
> > >     8:        b7 01 00 00 01 00 00 00         r1=1
> > > -  10:        b7 02 00 00 02 00 00 00         r2=2
> > > -  18:        18 06 00 00 38 00 00 00         r6=56 ll
> > > +  10:        b7 03 00 00 03 00 00 00         r3=3
> > > +  18:        18 02 00 00 38 00 00 00         r2=56 ll
> > >    20:        00 00 00 00 00 00 00 00[    ]*
> > >                       18: R_BPF_64_64 .text
> > > -  28:        8d 06 00 00 00 00 00 00         callx r6
> > > +  28:        8d 02 00 00 00 00 00 00         callx r2
> > >    30:        95 00 00 00 00 00 00 00         exit
> >
> > I don't see any reason for changing the test bodies like this.  If it is
> > about matching some llvm test, IMO consistency between binutils and llvm
> > testsuites is not a general goal we can (or should) aim to.
> >
> > Same applies to the other tests changed in the thunk below.
>
> As I said, I am happy to do whatever you like! I did it just so that I
> could visually check that the two matched and then I left it. In v4 I
> will revert this particular piece!
>
> >
> > >  0000000000000038 <bar>:
> > > diff --git a/gas/testsuite/gas/bpf/indcall-1-pseudoc.s b/gas/testsuite/gas/bpf/indcall-1-pseudoc.s
> > > index 2042697f15b..5639e288869 100644
> > > --- a/gas/testsuite/gas/bpf/indcall-1-pseudoc.s
> > > +++ b/gas/testsuite/gas/bpf/indcall-1-pseudoc.s
> > > @@ -4,9 +4,9 @@
> > >  main:
> > >       r0 = 1
> > >       r1 = 1
> > > -     r2 = 2
> > > -     r6 = bar ll
> > > -     callx r6
> > > +     r3 = 3
> > > +     r2 = bar ll
> > > +     callx r2
> > >       exit
> > >  bar:
> > >       r0 = 0
> > > diff --git a/gas/testsuite/gas/bpf/indcall-1.d b/gas/testsuite/gas/bpf/indcall-1.d
> > > index 51103bba2a1..1a2c36999b1 100644
> > > --- a/gas/testsuite/gas/bpf/indcall-1.d
> > > +++ b/gas/testsuite/gas/bpf/indcall-1.d
> > > @@ -1,5 +1,5 @@
> > > -#as: -EL -misa-spec=xbpf
> > > -#objdump: -dr -M xbpf,dec
> > > +#as: -EL -misa-spec=v1
> > > +#objdump: -dr -M v1,dec
> >
> > Likewise, I think this test can just omit the -M v1 and -ima-spec=v1
> > arguments now.
> >
>
> Ack!
>
> > >  #source: indcall-1.s
> > >  #name: BPF indirect call 1, normal syntax
> > >
> > > @@ -10,11 +10,11 @@ Disassembly of section \.text:
> > >  0000000000000000 <main>:
> > >     0:        b7 00 00 00 01 00 00 00         mov %r0,1
> > >     8:        b7 01 00 00 01 00 00 00         mov %r1,1
> > > -  10:        b7 02 00 00 02 00 00 00         mov %r2,2
> > > -  18:        18 06 00 00 38 00 00 00         lddw %r6,56
> > > +  10:        b7 03 00 00 03 00 00 00         mov %r3,3
> > > +  18:        18 02 00 00 38 00 00 00         lddw %r2,56
> > >    20:        00 00 00 00 00 00 00 00[    ]*
> > >                       18: R_BPF_64_64 .text
> > > -  28:        8d 06 00 00 00 00 00 00         call %r6
> > > +  28:        8d 02 00 00 00 00 00 00         call %r2
> > >    30:        95 00 00 00 00 00 00 00         exit
> > >
> > >  0000000000000038 <bar>:
> > > diff --git a/gas/testsuite/gas/bpf/indcall-1.s b/gas/testsuite/gas/bpf/indcall-1.s
> > > index 5d49e41040a..7fbeeeb9a38 100644
> > > --- a/gas/testsuite/gas/bpf/indcall-1.s
> > > +++ b/gas/testsuite/gas/bpf/indcall-1.s
> > > @@ -4,9 +4,9 @@
> > >  main:
> > >      mov %r0, 1
> > >      mov %r1, 1
> > > -    mov %r2, 2
> > > -    lddw %r6, bar
> > > -    call %r6
> > > +    mov %r3, 3
> > > +    lddw %r2, bar
> > > +    call %r2
> > >      exit
> > >
> > >  bar:
> > > diff --git a/include/opcode/bpf.h b/include/opcode/bpf.h
> > > index df1e3bd0918..97e25053175 100644
> > > --- a/include/opcode/bpf.h
> > > +++ b/include/opcode/bpf.h
> > > @@ -202,7 +202,7 @@ enum bpf_insn_id
> > >    BPF_INSN_JAR, BPF_INSN_JEQR, BPF_INSN_JGTR, BPF_INSN_JSGTR,
> > >    BPF_INSN_JGER, BPF_INSN_JSGER, BPF_INSN_JLTR, BPF_INSN_JSLTR,
> > >    BPF_INSN_JSLER, BPF_INSN_JLER, BPF_INSN_JSETR, BPF_INSN_JNER,
> > > -  BPF_INSN_CALLR, BPF_INSN_CALL, BPF_INSN_EXIT,
> > > +  BPF_INSN_CALLX, BPF_INSN_CALL, BPF_INSN_EXIT,
> >
> > I don't think it is a good idea to rename BPF_INSN_CALLR to
> > BPF_INSN_CALLX.
> >
> > At the moment the assembler uses the `callx' mnemonic for it and GCC
> > uses the same name because that is what clang does, but if/when the
> > corresponding instruction gets incorporated into BPF, I indend to push
> > for a better name, certainly not something as unmemorable and
> > indescriptive as `callx'.
>
> I will drop this change, as well! I know that Dave is working on this
> naming now on the standardization mailing list. I look forward to
> watching that argument! (I am definitely going to get butter with the
> popcorn!).
>
> I will have a v4 later today -- the day job calls for the next few hours! Sorry!
> Will

Sent! Sorry for the delay!
Will


>
>
> >
> > >    /* Compare-and-jump instructions (reg OP imm.)  */
> > >    BPF_INSN_JEQI, BPF_INSN_JGTI, BPF_INSN_JSGTI,
> > >    BPF_INSN_JGEI, BPF_INSN_JSGEI, BPF_INSN_JLTI, BPF_INSN_JSLTI,
> > > diff --git a/opcodes/bpf-opc.c b/opcodes/bpf-opc.c
> > > index 19e096501a2..23473fc0cd9 100644
> > > --- a/opcodes/bpf-opc.c
> > > +++ b/opcodes/bpf-opc.c
> > > @@ -272,8 +272,8 @@ const struct bpf_opcode bpf_opcodes[] =
> > >     BPF_V1, BPF_CODE, BPF_CLASS_JMP|BPF_CODE_JSET|BPF_SRC_X},
> > >    {BPF_INSN_JNER, "jne%W%dr , %sr , %d16", "if%w%dr != %sr%wgoto%w%d16",
> > >     BPF_V1, BPF_CODE, BPF_CLASS_JMP|BPF_CODE_JNE|BPF_SRC_X},
> > > -  {BPF_INSN_CALLR, "call%W%dr", "callx%w%dr",
> > > -   BPF_XBPF, BPF_CODE, BPF_CLASS_JMP|BPF_CODE_CALL|BPF_SRC_X},
> > > +  {BPF_INSN_CALLX, "call%W%dr", "callx%w%dr",
> > > +   BPF_V1, BPF_CODE, BPF_CLASS_JMP|BPF_CODE_CALL|BPF_SRC_X},
> > >    {BPF_INSN_CALL, "call%W%d32", "call%w%d32",
> > >     BPF_V1, BPF_CODE, BPF_CLASS_JMP|BPF_CODE_CALL|BPF_SRC_K},
> > >    {BPF_INSN_EXIT, "exit", "exit",

      reply	other threads:[~2024-02-14 22:13 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-02-14 16:02 [PATCH v3 0/1] Move callx (nee callr) to v1 ISA variant Will Hawkins
2024-02-14 16:03 ` [PATCH v3 1/1] objdump, as: Add callx support for BPF CPU v1 Will Hawkins
2024-02-14 16:30   ` Jose E. Marchesi
2024-02-14 16:36     ` Will Hawkins
2024-02-14 22:13       ` Will Hawkins [this message]

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