From: Kuan-Lin Chen <kuanlinchentw@gmail.com>
To: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: "binutils@sourceware.org Development" <binutils@sourceware.org>
Subject: Re: [PATCH] [RISCV] Support subtraction of .uleb128.
Date: Wed, 22 Jan 2020 07:26:00 -0000 [thread overview]
Message-ID: <CAJr6u0hMMhOVo5WpDJvNwS2U5bPGEBujW5qXyvuDgBOepK1BSQ@mail.gmail.com> (raw)
In-Reply-To: <mhng-bf7b317b-75dc-4000-b583-9074021d73fe@palmerdabbelt-glaptop>
[-- Attachment #1: Type: text/plain, Size: 33531 bytes --]
Hi,
This version patch updates as follows:
Fix the warning about uninitialized variable.
Set a limit to .uleb128 expressions as Palmer's suggestion.
Thanks.
Palmer Dabbelt <palmerdabbelt@google.com> 於 2020年1月10日 週五 上午7:19寫道：
>
> On Mon, 09 Dec 2019 21:42:58 PST (-0800), kuanlinchentw@gmail.com wrote:
> > Hi Palmer,
> >
> >> GCC gives me -Wmaybe-uninitialized for both of these.
> > May I know your gcc version?
> > I tried gcc-7.3.0 and gcc-8.2.0, and I didn't get the warning.
>
> $ gcc --version
> gcc (Debian 8.3.0-6) 8.3.0
> Copyright (C) 2018 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions. There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>
> >> I don't understand how this could possibly work: uleb128s can be long, so we
> >> can't just treat them as a single byte.
> > Yes, uleb128s can be long so I implement riscv_elf_ignore_reloc to
> > ignore the overflow checking.
> > And I relocate uleb128s by myself in perform_relocation.
> >
> >> I'm having trouble testing it, though,
> >> as I can't figure out how to emit R_RISCV_SET_ULEB128 alone. For example, when
> >> I try to insert a uleb128 in the assembler I'm not even getting a relocation:
> > .uleb128 only support subtract format. (.uleb128 .L1 - .L0)
> > It is impossible to get final the value and the length for ".uleb128
> > symbol" in assemble-time.
>
> Well, you know symbols are at most 64-bit on rv64 and 32-bit on rv32, so you
> can just emit enough space to encode any symbol. That's better than emitting 7
> bits, which is unlikely to encode any symbol.
>
> > I think ".uleb128 symbol" is meaningless.
> > Therefore, all targets just fill the value as assemble-time value
> > without relocations.
>
> If the assembler can't handle something then it needs to provide an error, it
> can't just generate incorrect code.
>
> >>I can get a R_RISCV_SUB_ULEB128, but it appears to be both producing the wrong
> >>value and garbaging up bytes after the relocation. For example:
> >
> > I get the same result in the object file but the different result in executable.
> > pal.o: file format elf64-littleriscv
> >
> > Disassembly of section .text:
> >
> > 0000000000000000 <_start>:
> > 0: 00000013 nop
> >
> > 0000000000000004 <.L0>:
> > 4: 00000013 nop
> >
> > 0000000000000008 <uleb_l1_l0>:
> > 8: 00100013 li zero,1
> > c: aa04 fsd fs1,16(a2)
> > c: R_RISCV_SET_ULEB128 .L1
> > c: R_RISCV_SUB_ULEB128 .L0
> > e: aaaa fsd fa0,336(sp)
> > 10: 00200013 li zero,2
> >
> >
> > a.out: file format elf64-littleriscv
> >
> >
> > Disassembly of section .text:
> >
> > 0000000000010078 <_start>:
> > 10078: 00000013 nop
> > 1007c: 00000013 nop
> >
> > 0000000000010080 <uleb_l1_l0>:
> > 10080: 00100013 li zero,1
> > 10084: aa04 fsd fs1,16(a2)
> > 10086: aaaa fsd fa0,336(sp)
> > 10088: 00200013 li zero,2
> >
> > Maybe there is something mismatched. But I don't have any idea currently.
> > Could you please give me more information about your flow?
>
> IIRC I just applied the patch on top of whatever was HEAD of binutils-gdb at
> the time, but I don't have the working directory around any more.
>
> > Thanks.
> >
> >> Presumably that's why I can't get a _SET alone.
> > I think it's meaningless to use _SET alone in assembly.
> >
> >> It looks like alignment is broken here after uleb128s, but it's not actually
> >> triggering an error in all cases. Having two of them in this test case doesn't
> >> trigger the issue, but an odd number does. For example, the following source
> > I think this alignment issue can be fixed by the following patch:
> > https://sourceware.org/ml/binutils/2019-12/msg00024.html
>
> Ya, thanks -- I think there's some issues there as well, IIRC I commented on
> it.
>
> >
> > Thanks for your review.
> >
> > Palmer Dabbelt <palmerdabbelt@google.com> 於 2019年12月7日 週六 上午7:47寫道：
> >>
> >> On Wed, 27 Nov 2019 00:11:50 PST (-0800), kuanlinchentw@gmail.com wrote:
> >> > The data length of uleb128 is variable. So linker must recalculate the
> >> > value of the subtraction. The patch leave relocations in object files
> >> > so that linker can relocate again after relaxation.
> >> >
> >> > bfd/ChangeLog:
> >> > * bfd-in2.h: Regenerated.
> >> > * elfnn-riscv.c (write_uleb128): New function.
> >> > (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
> >> > R_RISCV_SET_ULEB128 relocation.
> >> > (riscv_elf_relocate_section): Likewise.
> >> > * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
> >> > R_RISCV_SET_ULEB128.
> >> > (riscv_elf_ignore_reloc): New function.
> >> > * libbfd.h: Regenerated.
> >> > * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
> >> > New relocations to support .uleb128.
> >> >
> >> > gas/ChangeLog:
> >> > * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
> >> > BFD_RELOC_RISCV_SUB_ULEB128.
> >> > (riscv_insert_uleb128_fixes): New function.
> >> > (riscv_md_end): Scan rs_leb128 fragments.
> >> > (riscv_pseudo_table): Remove uleb128.
> >> >
> >> > include/ChangeLog:
> >> > * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
> >> >
> >> > ld/ChangeLog:
> >> > * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
> >> > * testsuite/ld-riscv-elf/uleb128.d: New test.
> >> > * testsuite/ld-riscv-elf/uleb128.s: New file.
> >> >
> >> > OK to commit?
> >>
> >> I'm having a lot of trouble trying to figure out how this works. LMK if I'm
> >> missing something, there's some comments in line:
> >>
> >> > From 9f7f0aaa484dee2b32c550f8cca4de18959f01e1 Mon Sep 17 00:00:00 2001
> >> > From: Kuan-Lin Chen <rufus@andestech.com>
> >> > Date: Thu, 14 Nov 2019 14:24:22 +0800
> >> > Subject: [PATCH] RISC-V: Support subtraction of .uleb128.
> >> >
> >> > The data length of uleb128 is variable. So linker must recalculate the
> >> > value of the subtraction. The patch leave relocations in object files
> >> > so that linker can relocate again after relaxation.
> >> >
> >> > bfd/ChangeLog:
> >> > * bfd-in2.h: Regenerated.
> >> > * elfnn-riscv.c (write_uleb128): New function.
> >> > (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
> >> > R_RISCV_SET_ULEB128 relocation.
> >> > (riscv_elf_relocate_section): Likewise.
> >> > * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
> >> > R_RISCV_SET_ULEB128.
> >> > (riscv_elf_ignore_reloc): New function.
> >> > * libbfd.h: Regenerated.
> >> > * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
> >> > New relocations to support .uleb128.
> >> >
> >> > gas/ChangeLog:
> >> > * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
> >> > BFD_RELOC_RISCV_SUB_ULEB128.
> >> > (riscv_insert_uleb128_fixes): New function.
> >> > (riscv_md_end): Scan rs_leb128 fragments.
> >> > (riscv_pseudo_table): Remove uleb128.
> >> >
> >> > include/ChangeLog:
> >> > * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
> >> >
> >> > ld/ChangeLog:
> >> > * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
> >> > * testsuite/ld-riscv-elf/uleb128.d: New test.
> >> > * testsuite/ld-riscv-elf/uleb128.s: New file.
> >> > ---
> >> > bfd/ChangeLog | 14 ++++
> >> > bfd/bfd-in2.h | 2 +
> >> > bfd/elfnn-riscv.c | 82 ++++++++++++++++++++++
> >> > bfd/elfxx-riscv.c | 51 ++++++++++++++
> >> > bfd/libbfd.h | 2 +
> >> > bfd/reloc.c | 4 ++
> >> > gas/ChangeLog | 8 +++
> >> > gas/config/tc-riscv.c | 47 ++++++++++++-
> >> > include/ChangeLog | 4 ++
> >> > include/elf/riscv.h | 2 +
> >> > ld/ChangeLog | 6 ++
> >> > ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp | 1 +
> >> > ld/testsuite/ld-riscv-elf/uleb128.d | 18 +++++
> >> > ld/testsuite/ld-riscv-elf/uleb128.s | 18 +++++
> >> > 14 files changed, 258 insertions(+), 1 deletion(-)
> >> > create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.d
> >> > create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.s
> >> >
> >> > diff --git a/bfd/ChangeLog b/bfd/ChangeLog
> >> > index 4a0852e577..d11ffde74c 100644
> >> > --- a/bfd/ChangeLog
> >> > +++ b/bfd/ChangeLog
> >> > @@ -1,3 +1,17 @@
> >> > +2019-11-27 Kuan-Lin Chen <kuanlinchentw@gmail.com>
> >> > +
> >> > + * bfd-in2.h: Regenerated.
> >> > + * elfnn-riscv.c (write_uleb128): New function.
> >> > + (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
> >> > + R_RISCV_SET_ULEB128 relocation.
> >> > + (riscv_elf_relocate_section): Likewise.
> >> > + * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
> >> > + R_RISCV_SET_ULEB128.
> >> > + (riscv_elf_ignore_reloc): New function.
> >> > + * libbfd.h: Regenerated.
> >> > + * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
> >> > + New relocations to support .uleb128.
> >> > +
> >> > 2019-11-27 Alan Modra <amodra@gmail.com>
> >> >
> >> > PR 23652
> >> > diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
> >> > index 44902fc8d0..a32708ebc2 100644
> >> > --- a/bfd/bfd-in2.h
> >> > +++ b/bfd/bfd-in2.h
> >> > @@ -4380,6 +4380,8 @@ number for the SBIC, SBIS, SBI and CBI instructions */
> >> > BFD_RELOC_RISCV_SET16,
> >> > BFD_RELOC_RISCV_SET32,
> >> > BFD_RELOC_RISCV_32_PCREL,
> >> > + BFD_RELOC_RISCV_SET_ULEB128,
> >> > + BFD_RELOC_RISCV_SUB_ULEB128,
> >> >
> >> > /* Renesas RL78 Relocations. */
> >> > BFD_RELOC_RL78_NEG8,
> >> > diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
> >> > index 997f786602..075ef6b82d 100644
> >> > --- a/bfd/elfnn-riscv.c
> >> > +++ b/bfd/elfnn-riscv.c
> >> > @@ -1419,6 +1419,26 @@ riscv_global_pointer_value (struct bfd_link_info *info)
> >> > return h->u.def.value + sec_addr (h->u.def.section);
> >> > }
> >> >
> >> > +/* Write VAL in uleb128 format to P, returning a pointer to the
> >> > + following byte.
> >> > + This code is copied from elf-attr.c. */
> >> > +
> >> > +static bfd_byte *
> >> > +write_uleb128 (bfd_byte *p, unsigned int val)
> >> > +{
> >> > + bfd_byte c;
> >> > + do
> >> > + {
> >> > + c = val & 0x7f;
> >> > + val >>= 7;
> >> > + if (val)
> >> > + c |= 0x80;
> >> > + *(p++) = c;
> >> > + }
> >> > + while (val);
> >> > + return p;
> >> > +}
> >> > +
> >> > /* Emplace a static relocation. */
> >> >
> >> > static bfd_reloc_status_type
> >> > @@ -1512,6 +1532,25 @@ perform_relocation (const reloc_howto_type *howto,
> >> > value = ENCODE_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value));
> >> > break;
> >> >
> >> > + case R_RISCV_SET_ULEB128:
> >> > + case R_RISCV_SUB_ULEB128:
> >> > + {
> >> > + unsigned int len = 0;
> >> > + bfd_byte *endp, *p;
> >> > +
> >> > + _bfd_read_unsigned_leb128 (input_bfd, contents + rel->r_offset, &len);
> >> > +
> >> > + /* Clean the contents value to zero. Do not reduce the length. */
> >> > + p = contents + rel->r_offset;
> >> > + endp = p + len -1;
> >> > + memset (p, 0x80, len);
> >> > + *(endp) = 0;
> >> > + p = write_uleb128 (p, value) - 1;
> >> > + if (p < endp)
> >> > + *p |= 0x80;
> >> > + return bfd_reloc_ok;
> >> > + }
> >> > +
> >> > case R_RISCV_32:
> >> > case R_RISCV_64:
> >> > case R_RISCV_ADD8:
> >> > @@ -1767,6 +1806,8 @@ riscv_elf_relocate_section (bfd *output_bfd,
> >> > struct elf_link_hash_entry **sym_hashes = elf_sym_hashes (input_bfd);
> >> > bfd_vma *local_got_offsets = elf_local_got_offsets (input_bfd);
> >> > bfd_boolean absolute;
> >> > + bfd_vma uleb128_vma;
> >> > + Elf_Internal_Rela *uleb128_rel = NULL;
> >> >
> >> > if (!riscv_init_pcrel_relocs (&pcrel_relocs))
> >> > return FALSE;
> >> > @@ -1871,6 +1912,47 @@ riscv_elf_relocate_section (bfd *output_bfd,
> >> > case R_RISCV_DELETE:
> >> > /* These require no special handling beyond perform_relocation. */
> >> > break;
> >> > + case R_RISCV_SET_ULEB128:
> >> > + if (!uleb128_rel)
> >> > + {
> >> > + /* Save the minuend to use later. */
> >> > + uleb128_vma = relocation;
> >> > + uleb128_rel = rel;
> >> > + continue;
> >> > + }
> >> > + else
> >> > + {
> >> > + if (uleb128_rel->r_offset != rel->r_offset)
> >> > + {
> >> > + (*_bfd_error_handler) (_("%pB: relocation %s mismatched. "),
> >> > + input_bfd, howto->name);
> >> > + bfd_set_error (bfd_error_bad_value);
> >> > + }
> >> > + relocation = relocation - uleb128_vma;
> >> > + uleb128_rel = NULL;
> >> > + break;
> >> > + }
> >> > +
> >> > + case R_RISCV_SUB_ULEB128:
> >> > + if (uleb128_rel)
> >> > + {
> >> > + if (uleb128_rel->r_offset != rel->r_offset)
> >> > + {
> >> > + (*_bfd_error_handler) (_("%pB: relocation %s mismatched. "),
> >> > + input_bfd, howto->name);
> >> > + bfd_set_error (bfd_error_bad_value);
> >> > + }
> >> > + relocation = uleb128_vma - relocation;
> >>
> >> GCC gives me -Wmaybe-uninitialized for both of these.
> >>
> >> > + uleb128_rel = NULL;
> >> > + break;
> >> > + }
> >> > + else
> >> > + {
> >> > + /* Save the subtrahend to use later. */
> >> > + uleb128_vma = relocation;
> >> > + uleb128_rel = rel;
> >> > + continue;
> >> > + }
> >> >
> >> > case R_RISCV_GOT_HI20:
> >> > if (h != NULL)
> >> > diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
> >> > index 245717f70f..c136ba2207 100644
> >> > --- a/bfd/elfxx-riscv.c
> >> > +++ b/bfd/elfxx-riscv.c
> >> > @@ -38,6 +38,8 @@
> >> > relocations for the debug info. */
> >> > static bfd_reloc_status_type riscv_elf_add_sub_reloc
> >> > (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
> >> > +static bfd_reloc_status_type riscv_elf_ignore_reloc
> >> > + (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
> >> >
> >> > /* The relocation table used for SHT_RELA sections. */
> >> >
> >> > @@ -855,8 +857,41 @@ static reloc_howto_type howto_table[] =
> >> > 0, /* src_mask */
> >> > MINUS_ONE, /* dst_mask */
> >> > FALSE), /* pcrel_offset */
> >> > +
> >> > + /* The length of unsigned-leb128 is variant, just assume the
> >> > + size is one byte here. */
> >> > + HOWTO (R_RISCV_SET_ULEB128, /* type */
> >> > + 0, /* rightshift */
> >> > + 0, /* size */
> >> > + 0, /* bitsize */
> >> > + FALSE, /* pc_relative */
> >> > + 0, /* bitpos */
> >> > + complain_overflow_dont, /* complain_on_overflow */
> >> > + riscv_elf_ignore_reloc, /* special_function */
> >> > + "R_RISCV_SET_ULEB128", /* name */
> >> > + FALSE, /* partial_inplace */
> >> > + 0, /* src_mask */
> >> > + 0, /* dst_mask */
> >> > + FALSE), /* pcrel_offset */
> >>
> >> I don't understand how this could possibly work: uleb128s can be long, so we
> >> can't just treat them as a single byte. I'm having trouble testing it, though,
> >> as I can't figure out how to emit R_RISCV_SET_ULEB128 alone. For example, when
> >> I try to insert a uleb128 in the assembler I'm not even getting a relocation:
> >>
> >> .text
> >> .globl _start
> >> _start:
> >> nop
> >> .L0:
> >> nop
> >> .L1:
> >> uleb_l0:
> >> addi x0, x0, 1
> >> .uleb128 .L0
> >> # Manually fix up the alignment, as .align is broken.
> >> .rept 3
> >> .byte 0xAA
> >> .endr
> >> addi x0, x0, 2
> >>
> >> $ objdump -dr
> >> test.o: file format elf64-littleriscv
> >>
> >>
> >> Disassembly of section .text:
> >>
> >> 0000000000000000 <_start>:
> >> 0: 00000013 nop
> >> 4: 00000013 nop
> >>
> >> 0000000000000008 <uleb_l0>:
> >> 8: 00100013 li zero,1
> >> c: aa04 fsd fs1,16(a2)
> >> e: aaaa fsd fa0,336(sp)
> >> 10: 00200013 li zero,2
> >>
> >> so then when I link I'm just getting the wrong value entirely.
> >>
> >> test: file format elf64-littleriscv
> >>
> >>
> >> Disassembly of section .text:
> >>
> >> 0000000000010078 <_start>:
> >> 10078: 00000013 nop
> >> 1007c: 00000013 nop
> >>
> >> 0000000000010080 <uleb_l0>:
> >> 10080: 00100013 li zero,1
> >> 10084: aa04 fsd fs1,16(a2)
> >> 10086: aaaa fsd fa0,336(sp)
> >> 10088: 00200013 li zero,2
> >>
> >> > + /* The length of unsigned-leb128 is variant, just assume the
> >> > + size is one byte here. */
> >> > + HOWTO (R_RISCV_SUB_ULEB128, /* type */
> >> > + 0, /* rightshift */
> >> > + 0, /* size */
> >> > + 0, /* bitsize */
> >> > + FALSE, /* pc_relative */
> >> > + 0, /* bitpos */
> >> > + complain_overflow_dont, /* complain_on_overflow */
> >> > + riscv_elf_ignore_reloc, /* special_function */
> >> > + "R_RISCV_SUB_ULEB128", /* name */
> >> > + FALSE, /* partial_inplace */
> >> > + 0, /* src_mask */
> >> > + 0, /* dst_mask */
> >> > + FALSE), /* pcrel_offset */
> >> > };
> >>
> >> I can get a R_RISCV_SUB_ULEB128, but it appears to be both producing the wrong
> >> value and garbaging up bytes after the relocation. For example:
> >>
> >> .text
> >> .globl _start
> >> _start:
> >> nop
> >> .L0:
> >> nop
> >> .L1:
> >> uleb_l1_l0:
> >> addi x0, x0, 1
> >> .uleb128 .L1 - .L0
> >> # Manually fix up the alignment, as .align is broken
> >> .rept 3
> >> .byte 0xAA
> >> .endr
> >> addi x0, x0, 2
> >>
> >> produces the relocation
> >>
> >> test.o: file format elf64-littleriscv
> >>
> >>
> >> Disassembly of section .text:
> >>
> >> 0000000000000000 <_start>:
> >> 0: 00000013 nop
> >>
> >> 0000000000000004 <.L0>:
> >> 4: 00000013 nop
> >>
> >> 0000000000000008 <uleb_l1_l0>:
> >> 8: 00100013 li zero,1
> >> c: aa04 fsd fs1,16(a2)
> >> c: R_RISCV_SET_ULEB128 .L1
> >> c: R_RISCV_SUB_ULEB128 .L0
> >> e: aaaa fsd fa0,336(sp)
> >> 10: 00200013 li zero,2
> >>
> >> but then goes and corrupts the resulting executable
> >>
> >>
> >> test: file format elf64-littleriscv
> >> Disassembly of section .text:
> >>
> >> 0000000000010078 <_start>:
> >> 10078: 00000013 nop
> >> 1007c: 00000013 nop
> >>
> >> 0000000000010080 <uleb_l1_l0>:
> >> 10080: 00100013 li zero,1
> >> 10084: ff84 sd s1,56(a5)
> >> 10086: 000ffffb 0xffffb
> >> 1008a: 0020 addi s0,sp,8
> >>
> >> I can't think of a way to make this work aside from just emitting uleb128s at
> >> their full length, which would make them work but would really defeat the
> >> purpose of the format. I guess we could then relax these, but that seems like
> >> a lot of work.
> >>
> >> > +
> >> > /* A mapping from BFD reloc types to RISC-V ELF reloc types. */
> >> >
> >> > struct elf_reloc_map
> >> > @@ -917,6 +952,8 @@ static const struct elf_reloc_map riscv_reloc_map[] =
> >> > { BFD_RELOC_RISCV_SET16, R_RISCV_SET16 },
> >> > { BFD_RELOC_RISCV_SET32, R_RISCV_SET32 },
> >> > { BFD_RELOC_RISCV_32_PCREL, R_RISCV_32_PCREL },
> >> > + { BFD_RELOC_RISCV_SET_ULEB128, R_RISCV_SET_ULEB128 },
> >> > + { BFD_RELOC_RISCV_SUB_ULEB128, R_RISCV_SUB_ULEB128 },
> >> > };
> >> >
> >> > /* Given a BFD reloc type, return a howto structure. */
> >> > @@ -1011,6 +1048,20 @@ riscv_elf_add_sub_reloc (bfd *abfd,
> >> > return bfd_reloc_ok;
> >> > }
> >> >
> >> > +/* Special handler for relocations which don't have to be relocated.
> >> > + This function just simply return bfd_reloc_ok. */
> >> > +static bfd_reloc_status_type
> >> > +riscv_elf_ignore_reloc (bfd *abfd ATTRIBUTE_UNUSED, arelent *reloc_entry,
> >> > + asymbol *symbol ATTRIBUTE_UNUSED,
> >> > + void *data ATTRIBUTE_UNUSED, asection *input_section,
> >> > + bfd *output_bfd, char **error_message ATTRIBUTE_UNUSED)
> >> > +{
> >> > + if (output_bfd != NULL)
> >> > + reloc_entry->address += input_section->output_offset;
> >> > +
> >> > + return bfd_reloc_ok;
> >> > +}
> >> > +
> >> > /* Parsing subset version.
> >> >
> >> > Return Value:
> >> > diff --git a/bfd/libbfd.h b/bfd/libbfd.h
> >> > index 77b732ee4b..7aa8f91504 100644
> >> > --- a/bfd/libbfd.h
> >> > +++ b/bfd/libbfd.h
> >> > @@ -2327,6 +2327,8 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
> >> > "BFD_RELOC_RISCV_SET16",
> >> > "BFD_RELOC_RISCV_SET32",
> >> > "BFD_RELOC_RISCV_32_PCREL",
> >> > + "BFD_RELOC_RISCV_SET_ULEB128",
> >> > + "BFD_RELOC_RISCV_SUB_ULEB128",
> >> > "BFD_RELOC_RL78_NEG8",
> >> > "BFD_RELOC_RL78_NEG16",
> >> > "BFD_RELOC_RL78_NEG24",
> >> > diff --git a/bfd/reloc.c b/bfd/reloc.c
> >> > index b00b79f319..9b8b75ad21 100644
> >> > --- a/bfd/reloc.c
> >> > +++ b/bfd/reloc.c
> >> > @@ -5212,6 +5212,10 @@ ENUMX
> >> > BFD_RELOC_RISCV_SET32
> >> > ENUMX
> >> > BFD_RELOC_RISCV_32_PCREL
> >> > +ENUMX
> >> > + BFD_RELOC_RISCV_SET_ULEB128
> >> > +ENUMX
> >> > + BFD_RELOC_RISCV_SUB_ULEB128
> >> > ENUMDOC
> >> > RISC-V relocations.
> >> >
> >> > diff --git a/gas/ChangeLog b/gas/ChangeLog
> >> > index 09991524da..e53ac0895b 100644
> >> > --- a/gas/ChangeLog
> >> > +++ b/gas/ChangeLog
> >> > @@ -1,3 +1,11 @@
> >> > +2019-11-27 Kuan-Lin Chen <kuanlinchentw@gmail.com>
> >> > +
> >> > + * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
> >> > + BFD_RELOC_RISCV_SUB_ULEB128.
> >> > + (riscv_insert_uleb128_fixes): New function.
> >> > + (riscv_md_end): Scan rs_leb128 fragments.
> >> > + (riscv_pseudo_table): Remove uleb128.
> >> > +
> >> > 2019-11-25 Andrew Pinski <apinski@marvell.com>
> >> >
> >> > * config/tc-aarch64.c (md_begin): Use correct
> >> > diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
> >> > index e50505138e..c35c591c0a 100644
> >> > --- a/gas/config/tc-riscv.c
> >> > +++ b/gas/config/tc-riscv.c
> >> > @@ -2392,6 +2392,9 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
> >> > case BFD_RELOC_RISCV_SUB32:
> >> > case BFD_RELOC_RISCV_SUB64:
> >> > case BFD_RELOC_RISCV_RELAX:
> >> > + /* cvt_frag_to_fill () has called output_leb128 (). */
> >> > + case BFD_RELOC_RISCV_SET_ULEB128:
> >> > + case BFD_RELOC_RISCV_SUB_ULEB128:
> >> > break;
> >> >
> >> > case BFD_RELOC_RISCV_TPREL_HI20:
> >> > @@ -3127,11 +3130,54 @@ riscv_set_public_attributes (void)
> >> > riscv_write_out_arch_attr ();
> >> > }
> >> >
> >> > +/* Scan uleb128 subtraction expressions and insert fixups for them.
> >> > + e.g., .uleb128 .L1 - .L0
> >> > + Becuase relaxation may change the value of the subtraction, we
> >> > + must resolve them in link-time. */
> >> > +
> >> > +static void
> >> > +riscv_insert_uleb128_fixes (bfd *abfd ATTRIBUTE_UNUSED,
> >> > + asection *sec, void *xxx ATTRIBUTE_UNUSED)
> >> > +{
> >> > + segment_info_type *seginfo = seg_info (sec);
> >> > + struct frag *fragP;
> >> > +
> >> > + subseg_set (sec, 0);
> >> > +
> >> > + for (fragP = seginfo->frchainP->frch_root;
> >> > + fragP; fragP = fragP->fr_next)
> >> > + {
> >> > + expressionS *exp, *exp_dup;
> >> > +
> >> > + if (fragP->fr_type != rs_leb128 || fragP->fr_symbol == NULL)
> >> > + continue;
> >> > +
> >> > + exp = symbol_get_value_expression (fragP->fr_symbol);
> >> > +
> >> > + if (exp->X_op != O_subtract)
> >> > + continue;
> >>
> >> Presumably that's why I can't get a _SET alone.
> >>
> >> > +
> >> > + /* Only unsigned leb128 can be handle. */
> >> > + gas_assert (fragP->fr_subtype == 0);
> >> > + exp_dup = xmemdup (exp, sizeof (*exp), sizeof (*exp));
> >> > + exp_dup->X_op = O_symbol;
> >> > + exp_dup->X_op_symbol = NULL;
> >> > +
> >> > + /* Insert relocations to resolve the subtraction in link-time. */
> >> > + fix_new_exp (fragP, fragP->fr_fix, 0,
> >> > + exp_dup, 0, BFD_RELOC_RISCV_SET_ULEB128);
> >> > + exp_dup->X_add_symbol = exp->X_op_symbol;
> >> > + fix_new_exp (fragP, fragP->fr_fix, 0,
> >> > + exp_dup, 0, BFD_RELOC_RISCV_SUB_ULEB128);
> >> > + }
> >> > +}
> >> > +
> >> > /* Called after all assembly has been done. */
> >> >
> >> > void
> >> > riscv_md_end (void)
> >> > {
> >> > + bfd_map_over_sections (stdoutput, riscv_insert_uleb128_fixes, NULL);
> >> > riscv_set_public_attributes ();
> >> > }
> >> >
> >> > @@ -3215,7 +3261,6 @@ static const pseudo_typeS riscv_pseudo_table[] =
> >> > {"dtprelword", s_dtprel, 4},
> >> > {"dtpreldword", s_dtprel, 8},
> >> > {"bss", s_bss, 0},
> >> > - {"uleb128", s_riscv_leb128, 0},
> >> > {"sleb128", s_riscv_leb128, 1},
> >> > {"insn", s_riscv_insn, 0},
> >> > {"attribute", s_riscv_attribute, 0},
> >> > diff --git a/include/ChangeLog b/include/ChangeLog
> >> > index 47bb86cf71..c290b245c6 100644
> >> > --- a/include/ChangeLog
> >> > +++ b/include/ChangeLog
> >> > @@ -1,3 +1,7 @@
> >> > +2019-11-27 Kuan-Lin Chen <kuanlinchentw@gmail.com>
> >> > +
> >> > + * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
> >> > +
> >> > 2019-11-25 Alan Modra <amodra@gmail.com>
> >> >
> >> > * coff/ti.h (GET_SCNHDR_SIZE, PUT_SCNHDR_SIZE, GET_SCN_SCNLEN),
> >> > diff --git a/include/elf/riscv.h b/include/elf/riscv.h
> >> > index 2f98aa4a3e..030679b35f 100644
> >> > --- a/include/elf/riscv.h
> >> > +++ b/include/elf/riscv.h
> >> > @@ -88,6 +88,8 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
> >> > RELOC_NUMBER (R_RISCV_SET16, 55)
> >> > RELOC_NUMBER (R_RISCV_SET32, 56)
> >> > RELOC_NUMBER (R_RISCV_32_PCREL, 57)
> >> > + RELOC_NUMBER (R_RISCV_SET_ULEB128, 58)
> >> > + RELOC_NUMBER (R_RISCV_SUB_ULEB128, 59)
> >> > END_RELOC_NUMBERS (R_RISCV_max)
> >> >
> >> > /* Processor specific flags for the ELF header e_flags field. */
> >> > diff --git a/ld/ChangeLog b/ld/ChangeLog
> >> > index 969ab78035..5c2e406101 100644
> >> > --- a/ld/ChangeLog
> >> > +++ b/ld/ChangeLog
> >> > @@ -1,3 +1,9 @@
> >> > +2019-11-27 Kuan-Lin Chen <kuanlinchentw@gmail.com>
> >> > +
> >> > + * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
> >> > + * testsuite/ld-riscv-elf/uleb128.d: New test.
> >> > + * testsuite/ld-riscv-elf/uleb128.s: New file.
> >> > +
> >> > 2019-11-26 Martin Liska <mliska@suse.cz>
> >> >
> >> > * scripttempl/arclinux.sc: Add .text.sorted.* which is sorted
> >> > diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> >> > index 7aabbdd641..809e40f08d 100644
> >> > --- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> >> > +++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
> >> > @@ -38,6 +38,7 @@ if [istarget "riscv*-*-*"] {
> >> > run_dump_test "attr-merge-priv-spec"
> >> > run_dump_test "attr-merge-arch-failed-01"
> >> > run_dump_test "attr-merge-stack-align-failed"
> >> > + run_dump_test "uleb128"
> >> > run_ld_link_tests {
> >> > { "Weak reference 32" "-T weakref.ld -melf32lriscv" ""
> >> > "-march=rv32i -mabi=ilp32" {weakref32.s}
> >> > diff --git a/ld/testsuite/ld-riscv-elf/uleb128.d b/ld/testsuite/ld-riscv-elf/uleb128.d
> >> > new file mode 100644
> >> > index 0000000000..a921478e98
> >> > --- /dev/null
> >> > +++ b/ld/testsuite/ld-riscv-elf/uleb128.d
> >> > @@ -0,0 +1,18 @@
> >> > +#source: uleb128.s
> >> > +#as: -march=rv32ic
> >> > +#ld: -melf32lriscv
> >> > +#objdump: -d
> >> > +
> >> > +.*:[ ]+file format .*
> >> > +
> >> > +Disassembly of section .text:
> >> > +
> >> > +.* <_start>:
> >> > +.*jal.*<bar>
> >> > +.*jal.*<bar>
> >> > +.*jal.*<bar>
> >> > +.*jal.*<bar>
> >> > +.*jal.*<bar>
> >> > +.*jal.*<bar>
> >> > +.*:[ ]+0e0c.*
> >> > +#pass
> >> > diff --git a/ld/testsuite/ld-riscv-elf/uleb128.s b/ld/testsuite/ld-riscv-elf/uleb128.s
> >> > new file mode 100644
> >> > index 0000000000..f7d23be163
> >> > --- /dev/null
> >> > +++ b/ld/testsuite/ld-riscv-elf/uleb128.s
> >> > @@ -0,0 +1,18 @@
> >> > +.text
> >> > +.globl bar
> >> > +.globl _start
> >> > +.option rvc
> >> > +.align 2
> >> > +_start:
> >> > +.L0:
> >> > + .rept 6
> >> > + call bar
> >> > + .endr
> >> > +.align 2
> >> > +.L1:
> >> > + .uleb128 .L1 - .L0
> >> > + .uleb128 .L2 - .L0
> >> > +.L2:
> >> > +.align 2
> >> > +bar:
> >> > + nop
> >>
> >> It looks like alignment is broken here after uleb128s, but it's not actually
> >> triggering an error in all cases. Having two of them in this test case doesn't
> >> trigger the issue, but an odd number does. For example, the following source
> >>
> >> .text
> >> .globl _start
> >> .align 2
> >> _start:
> >> .uleb128 _start
> >> .align 2
> >> _end:
> >> nop
> >>
> >> links _end to a misaligned symbol
> >>
> >> Disassembly of section .text:
> >>
> >> 0000000000010078 <_start>:
> >> ...
> >>
> >> 0000000000010079 <_end>:
> >> 10079: 00000013 nop
> >> 1007d: 0000 unimp
> >> ...
> >>
> >> I'm assuming that's because norvc assumes 4-byte alignment in text sections, so
> >> it's just eliding the alingment directives. With RVC I do get an error message
> >>
> >> .text
> >> .globl _start
> >> .option rvc
> >> .align 2
> >> _start:
> >> .uleb128 _start
> >> .align 2
> >> _end:
> >> nop
> >>
> >> ./install/bin/riscv64-unknown-linux-gnu-ld: test.o(.text+0x1): 3 bytes required for alignment to 4-byte boundary, but only 2 present
> >> ./install/bin/riscv64-unknown-linux-gnu-ld: can't relax section: bad value
> >>
> >>
> >
> >
> > --
> > Best regards,
> > Kuan-Lin Chen.
> > kuanlinchentw@gmail.com
--
Best regards,
Kuan-Lin Chen.
kuanlinchentw@gmail.com
[-- Attachment #2: 0001-RISC-V-Support-subtraction-of-.uleb128.patch --]
[-- Type: application/octet-stream, Size: 16325 bytes --]
From d733abde65adca030288819c2221953ed40d7a64 Mon Sep 17 00:00:00 2001
From: Kuan-Lin Chen <rufus@andestech.com>
Date: Thu, 14 Nov 2019 14:24:22 +0800
Subject: [PATCH] RISC-V: Support subtraction of .uleb128.
The data length of uleb128 is variable. So linker must recalculate the
value of the subtraction. The patch leave relocations in object files
so that linker can relocate again after relaxation.
bfd/ChangeLog:
* bfd-in2.h: Regenerated.
* elfnn-riscv.c (write_uleb128): New function.
(perform_relocation): Perform R_RISCV_SUB_ULEB128 and
R_RISCV_SET_ULEB128 relocation.
(riscv_elf_relocate_section): Likewise.
* elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
R_RISCV_SET_ULEB128.
(riscv_elf_ignore_reloc): New function.
* libbfd.h: Regenerated.
* reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
New relocations to support .uleb128.
gas/ChangeLog:
* config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
BFD_RELOC_RISCV_SUB_ULEB128.
(riscv_insert_uleb128_fixes): New function.
(riscv_md_end): Scan rs_leb128 fragments.
(riscv_pseudo_table): Remove uleb128.
include/ChangeLog:
* elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
ld/ChangeLog:
* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
* testsuite/ld-riscv-elf/uleb128.d: New test.
* testsuite/ld-riscv-elf/uleb128.s: New file.
---
bfd/ChangeLog | 14 ++++
bfd/bfd-in2.h | 2 +
bfd/elfnn-riscv.c | 84 +++++++++++++++++++++-
bfd/elfxx-riscv.c | 51 +++++++++++++
bfd/libbfd.h | 2 +
bfd/reloc.c | 4 ++
gas/ChangeLog | 8 +++
gas/config/tc-riscv.c | 55 +++++++++++++-
include/ChangeLog | 4 ++
include/elf/riscv.h | 2 +
ld/ChangeLog | 6 ++
ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp | 1 +
ld/testsuite/ld-riscv-elf/uleb128.d | 18 +++++
ld/testsuite/ld-riscv-elf/uleb128.s | 18 +++++
14 files changed, 266 insertions(+), 3 deletions(-)
create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.d
create mode 100644 ld/testsuite/ld-riscv-elf/uleb128.s
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 45f2499735..94082f6213 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,17 @@
+2020-01-22 Kuan-Lin Chen <kuanlinchentw@gmail.com>
+
+ * bfd-in2.h: Regenerated.
+ * elfnn-riscv.c (write_uleb128): New function.
+ (perform_relocation): Perform R_RISCV_SUB_ULEB128 and
+ R_RISCV_SET_ULEB128 relocation.
+ (riscv_elf_relocate_section): Likewise.
+ * elfxx-riscv.c (howto_table): Add R_RISCV_SUB_ULEB128 and
+ R_RISCV_SET_ULEB128.
+ (riscv_elf_ignore_reloc): New function.
+ * libbfd.h: Regenerated.
+ * reloc.c (BFD_RELOC_RISCV_SET_ULEB128, BFD_RELOC_RISCV_SUB_ULEB128):
+ New relocations to support .uleb128.
+
2020-01-20 Nick Clifton <nickc@redhat.com>
* po/pt.po: Updates Portuguese translation.
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 7c13bc8c91..e43c3a5557 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -4383,6 +4383,8 @@ number for the SBIC, SBIS, SBI and CBI instructions */
BFD_RELOC_RISCV_SET16,
BFD_RELOC_RISCV_SET32,
BFD_RELOC_RISCV_32_PCREL,
+ BFD_RELOC_RISCV_SET_ULEB128,
+ BFD_RELOC_RISCV_SUB_ULEB128,
/* Renesas RL78 Relocations. */
BFD_RELOC_RL78_NEG8,
diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c
index 46f0100ace..74c19bf0fc 100644
--- a/bfd/elfnn-riscv.c
+++ b/bfd/elfnn-riscv.c
@@ -1419,6 +1419,26 @@ riscv_global_pointer_value (struct bfd_link_info *info)
return h->u.def.value + sec_addr (h->u.def.section);
}
+/* Write VAL in uleb128 format to P, returning a pointer to the
+ following byte.
+ This code is copied from elf-attr.c. */
+
+static bfd_byte *
+write_uleb128 (bfd_byte *p, unsigned int val)
+{
+ bfd_byte c;
+ do
+ {
+ c = val & 0x7f;
+ val >>= 7;
+ if (val)
+ c |= 0x80;
+ *(p++) = c;
+ }
+ while (val);
+ return p;
+}
+
/* Emplace a static relocation. */
static bfd_reloc_status_type
@@ -1512,6 +1532,25 @@ perform_relocation (const reloc_howto_type *howto,
value = ENCODE_RVC_LUI_IMM (RISCV_CONST_HIGH_PART (value));
break;
+ case R_RISCV_SET_ULEB128:
+ case R_RISCV_SUB_ULEB128:
+ {
+ unsigned int len = 0;
+ bfd_byte *endp, *p;
+
+ _bfd_read_unsigned_leb128 (input_bfd, contents + rel->r_offset, &len);
+
+ /* Clean the contents value to zero. Do not reduce the length. */
+ p = contents + rel->r_offset;
+ endp = p + len -1;
+ memset (p, 0x80, len - 1);
+ *(endp) = 0;
+ p = write_uleb128 (p, value) - 1;
+ if (p < endp)
+ *p |= 0x80;
+ return bfd_reloc_ok;
+ }
+
case R_RISCV_32:
case R_RISCV_64:
case R_RISCV_ADD8:
@@ -1767,6 +1806,8 @@ riscv_elf_relocate_section (bfd *output_bfd,
struct elf_link_hash_entry **sym_hashes = elf_sym_hashes (input_bfd);
bfd_vma *local_got_offsets = elf_local_got_offsets (input_bfd);
bfd_boolean absolute;
+ bfd_vma uleb128_vma = 0;
+ Elf_Internal_Rela *uleb128_rel = NULL;
if (!riscv_init_pcrel_relocs (&pcrel_relocs))
return FALSE;
@@ -1778,7 +1819,7 @@ riscv_elf_relocate_section (bfd *output_bfd,
struct elf_link_hash_entry *h;
Elf_Internal_Sym *sym;
asection *sec;
- bfd_vma relocation;
+ bfd_vma relocation = 0;
bfd_reloc_status_type r = bfd_reloc_ok;
const char *name;
bfd_vma off, ie_off;
@@ -1871,6 +1912,47 @@ riscv_elf_relocate_section (bfd *output_bfd,
case R_RISCV_DELETE:
/* These require no special handling beyond perform_relocation. */
break;
+ case R_RISCV_SET_ULEB128:
+ if (!uleb128_rel)
+ {
+ /* Save the minuend to use later. */
+ uleb128_vma = relocation;
+ uleb128_rel = rel;
+ continue;
+ }
+ else
+ {
+ if (uleb128_rel->r_offset != rel->r_offset)
+ {
+ msg = ("R_RISCV_SET_ULEB128 and R_RISCV_SUB_ULEB128 are mismatched. ");
+ r = bfd_reloc_dangerous;
+ break;
+ }
+ relocation = relocation - uleb128_vma;
+ uleb128_rel = NULL;
+ break;
+ }
+
+ case R_RISCV_SUB_ULEB128:
+ if (uleb128_rel)
+ {
+ if (uleb128_rel->r_offset != rel->r_offset)
+ {
+ msg = ("R_RISCV_SET_ULEB128 and R_RISCV_SUB_ULEB128 are mismatched. ");
+ r = bfd_reloc_dangerous;
+ break;
+ }
+ relocation = uleb128_vma - relocation;
+ uleb128_rel = NULL;
+ break;
+ }
+ else
+ {
+ /* Save the subtrahend to use later. */
+ uleb128_vma = relocation;
+ uleb128_rel = rel;
+ continue;
+ }
case R_RISCV_GOT_HI20:
if (h != NULL)
diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index 66e343f4a5..244353573b 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -38,6 +38,8 @@
relocations for the debug info. */
static bfd_reloc_status_type riscv_elf_add_sub_reloc
(bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
+static bfd_reloc_status_type riscv_elf_ignore_reloc
+ (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
/* The relocation table used for SHT_RELA sections. */
@@ -855,8 +857,41 @@ static reloc_howto_type howto_table[] =
0, /* src_mask */
MINUS_ONE, /* dst_mask */
FALSE), /* pcrel_offset */
+
+ /* The length of unsigned-leb128 is variable, just assume the
+ size is one byte here. */
+ HOWTO (R_RISCV_SET_ULEB128, /* type */
+ 0, /* rightshift */
+ 0, /* size */
+ 0, /* bitsize */
+ FALSE, /* pc_relative */
+ 0, /* bitpos */
+ complain_overflow_dont, /* complain_on_overflow */
+ riscv_elf_ignore_reloc, /* special_function */
+ "R_RISCV_SET_ULEB128", /* name */
+ FALSE, /* partial_inplace */
+ 0, /* src_mask */
+ 0, /* dst_mask */
+ FALSE), /* pcrel_offset */
+
+ /* The length of unsigned-leb128 is variable, just assume the
+ size is one byte here. */
+ HOWTO (R_RISCV_SUB_ULEB128, /* type */
+ 0, /* rightshift */
+ 0, /* size */
+ 0, /* bitsize */
+ FALSE, /* pc_relative */
+ 0, /* bitpos */
+ complain_overflow_dont, /* complain_on_overflow */
+ riscv_elf_ignore_reloc, /* special_function */
+ "R_RISCV_SUB_ULEB128", /* name */
+ FALSE, /* partial_inplace */
+ 0, /* src_mask */
+ 0, /* dst_mask */
+ FALSE), /* pcrel_offset */
};
+
/* A mapping from BFD reloc types to RISC-V ELF reloc types. */
struct elf_reloc_map
@@ -917,6 +952,8 @@ static const struct elf_reloc_map riscv_reloc_map[] =
{ BFD_RELOC_RISCV_SET16, R_RISCV_SET16 },
{ BFD_RELOC_RISCV_SET32, R_RISCV_SET32 },
{ BFD_RELOC_RISCV_32_PCREL, R_RISCV_32_PCREL },
+ { BFD_RELOC_RISCV_SET_ULEB128, R_RISCV_SET_ULEB128 },
+ { BFD_RELOC_RISCV_SUB_ULEB128, R_RISCV_SUB_ULEB128 },
};
/* Given a BFD reloc type, return a howto structure. */
@@ -1011,6 +1048,20 @@ riscv_elf_add_sub_reloc (bfd *abfd,
return bfd_reloc_ok;
}
+/* Special handler for relocations which don't have to be relocated.
+ This function just simply return bfd_reloc_ok. */
+static bfd_reloc_status_type
+riscv_elf_ignore_reloc (bfd *abfd ATTRIBUTE_UNUSED, arelent *reloc_entry,
+ asymbol *symbol ATTRIBUTE_UNUSED,
+ void *data ATTRIBUTE_UNUSED, asection *input_section,
+ bfd *output_bfd, char **error_message ATTRIBUTE_UNUSED)
+{
+ if (output_bfd != NULL)
+ reloc_entry->address += input_section->output_offset;
+
+ return bfd_reloc_ok;
+}
+
/* Parsing subset version.
Return Value:
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index d97d4e57a7..74d12d8b99 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -2327,6 +2327,8 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
"BFD_RELOC_RISCV_SET16",
"BFD_RELOC_RISCV_SET32",
"BFD_RELOC_RISCV_32_PCREL",
+ "BFD_RELOC_RISCV_SET_ULEB128",
+ "BFD_RELOC_RISCV_SUB_ULEB128",
"BFD_RELOC_RL78_NEG8",
"BFD_RELOC_RL78_NEG16",
"BFD_RELOC_RL78_NEG24",
diff --git a/bfd/reloc.c b/bfd/reloc.c
index 33cd67150c..9b797e7920 100644
--- a/bfd/reloc.c
+++ b/bfd/reloc.c
@@ -5212,6 +5212,10 @@ ENUMX
BFD_RELOC_RISCV_SET32
ENUMX
BFD_RELOC_RISCV_32_PCREL
+ENUMX
+ BFD_RELOC_RISCV_SET_ULEB128
+ENUMX
+ BFD_RELOC_RISCV_SUB_ULEB128
ENUMDOC
RISC-V relocations.
diff --git a/gas/ChangeLog b/gas/ChangeLog
index 8f414396f5..3beb4060c2 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,11 @@
+2020-01-22 Kuan-Lin Chen <kuanlinchentw@gmail.com>
+
+ * config/tc-riscv.c (md_apply_fix): Add BFD_RELOC_RISCV_SET_ULEB128 and
+ BFD_RELOC_RISCV_SUB_ULEB128.
+ (riscv_insert_uleb128_fixes): New function.
+ (riscv_md_end): Scan rs_leb128 fragments.
+ (riscv_pseudo_table): Remove uleb128.
+
2020-01-21 Jan Beulich <jbeulich@suse.com>
* testsuite/gas/i386/inval-crc32.s,
diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 21fff8ffab..61094fab3a 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -2392,6 +2392,9 @@ md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
case BFD_RELOC_RISCV_SUB32:
case BFD_RELOC_RISCV_SUB64:
case BFD_RELOC_RISCV_RELAX:
+ /* cvt_frag_to_fill () has called output_leb128 (). */
+ case BFD_RELOC_RISCV_SET_ULEB128:
+ case BFD_RELOC_RISCV_SUB_ULEB128:
break;
case BFD_RELOC_RISCV_TPREL_HI20:
@@ -3067,8 +3070,11 @@ s_riscv_leb128 (int sign)
char *save_in = input_line_pointer;
expression (&exp);
- if (exp.X_op != O_constant)
- as_bad (_("non-constant .%cleb128 is not supported"), sign ? 's' : 'u');
+ if (sign && exp.X_op != O_constant)
+ as_bad (_("non-constant .sleb128 is not supported"));
+ else if (!sign && exp.X_op != O_constant && exp.X_op != O_subtract)
+ as_bad (_(".uleb128 only supports constant or subtract expressions."));
+
demand_empty_rest_of_line ();
input_line_pointer = save_in;
@@ -3131,11 +3137,56 @@ riscv_set_public_attributes (void)
riscv_write_out_arch_attr ();
}
+/* Scan uleb128 subtraction expressions and insert fixups for them.
+ e.g., .uleb128 .L1 - .L0
+ Because relaxation may change the value of the subtraction, we
+ must resolve them at link-time. */
+
+static void
+riscv_insert_uleb128_fixes (bfd *abfd ATTRIBUTE_UNUSED,
+ asection *sec, void *xxx ATTRIBUTE_UNUSED)
+{
+ segment_info_type *seginfo = seg_info (sec);
+ struct frag *fragP;
+
+ subseg_set (sec, 0);
+
+ for (fragP = seginfo->frchainP->frch_root;
+ fragP; fragP = fragP->fr_next)
+ {
+ expressionS *exp, *exp_dup;
+
+ if (fragP->fr_type != rs_leb128 || fragP->fr_symbol == NULL)
+ continue;
+
+ exp = symbol_get_value_expression (fragP->fr_symbol);
+
+ if (exp->X_op != O_subtract)
+ continue;
+
+ /* Only unsigned leb128 can be handled. */
+ gas_assert (fragP->fr_subtype == 0);
+ exp_dup = xmemdup (exp, sizeof (*exp), sizeof (*exp));
+ exp_dup->X_op = O_symbol;
+ exp_dup->X_op_symbol = NULL;
+
+ /* Insert relocations to resolve the subtraction at link-time. */
+ fix_new_exp (fragP, fragP->fr_fix, 0,
+ exp_dup, 0, BFD_RELOC_RISCV_SET_ULEB128);
+ exp_dup->X_add_symbol = exp->X_op_symbol;
+ fix_new_exp (fragP, fragP->fr_fix, 0,
+ exp_dup, 0, BFD_RELOC_RISCV_SUB_ULEB128);
+ }
+}
+
/* Called after all assembly has been done. */
void
riscv_md_end (void)
{
+
+ if (riscv_opts.relax)
+ bfd_map_over_sections (stdoutput, riscv_insert_uleb128_fixes, NULL);
riscv_set_public_attributes ();
}
diff --git a/include/ChangeLog b/include/ChangeLog
index c7fd4ab141..67ac887fe8 100644
--- a/include/ChangeLog
+++ b/include/ChangeLog
@@ -1,3 +1,7 @@
+2020-01-06 Kuan-Lin Chen <kuanlinchentw@gmail.com>
+
+ * elf/riscv.h ((R_RISCV_SET_ULEB128, (R_RISCV_SUB_ULEB128): Define.
+
2020-01-18 Nick Clifton <nickc@redhat.com>
Binutils 2.34 branch created.
diff --git a/include/elf/riscv.h b/include/elf/riscv.h
index 5062a4998c..a839a0c843 100644
--- a/include/elf/riscv.h
+++ b/include/elf/riscv.h
@@ -88,6 +88,8 @@ START_RELOC_NUMBERS (elf_riscv_reloc_type)
RELOC_NUMBER (R_RISCV_SET16, 55)
RELOC_NUMBER (R_RISCV_SET32, 56)
RELOC_NUMBER (R_RISCV_32_PCREL, 57)
+ RELOC_NUMBER (R_RISCV_SET_ULEB128, 58)
+ RELOC_NUMBER (R_RISCV_SUB_ULEB128, 59)
END_RELOC_NUMBERS (R_RISCV_max)
/* Processor specific flags for the ELF header e_flags field. */
diff --git a/ld/ChangeLog b/ld/ChangeLog
index d8949bbc38..c9b5d194a5 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,9 @@
+2020-01-06 Kuan-Lin Chen <kuanlinchentw@gmail.com>
+
+ * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add uleb128.
+ * testsuite/ld-riscv-elf/uleb128.d: New test.
+ * testsuite/ld-riscv-elf/uleb128.s: New file.
+
2020-01-22 Yuri Chornoivan <yurchor@mageia.org>
PR 25417
diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
index 0e9750e496..412c00d1ec 100644
--- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
+++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp
@@ -38,6 +38,7 @@ if [istarget "riscv*-*-*"] {
run_dump_test "attr-merge-priv-spec"
run_dump_test "attr-merge-arch-failed-01"
run_dump_test "attr-merge-stack-align-failed"
+ run_dump_test "uleb128"
run_ld_link_tests {
{ "Weak reference 32" "-T weakref.ld -melf32lriscv" ""
"-march=rv32i -mabi=ilp32" {weakref32.s}
diff --git a/ld/testsuite/ld-riscv-elf/uleb128.d b/ld/testsuite/ld-riscv-elf/uleb128.d
new file mode 100644
index 0000000000..a921478e98
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/uleb128.d
@@ -0,0 +1,18 @@
+#source: uleb128.s
+#as: -march=rv32ic
+#ld: -melf32lriscv
+#objdump: -d
+
+.*:[ ]+file format .*
+
+Disassembly of section .text:
+
+.* <_start>:
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*jal.*<bar>
+.*:[ ]+0e0c.*
+#pass
diff --git a/ld/testsuite/ld-riscv-elf/uleb128.s b/ld/testsuite/ld-riscv-elf/uleb128.s
new file mode 100644
index 0000000000..f7d23be163
--- /dev/null
+++ b/ld/testsuite/ld-riscv-elf/uleb128.s
@@ -0,0 +1,18 @@
+.text
+.globl bar
+.globl _start
+.option rvc
+.align 2
+_start:
+.L0:
+ .rept 6
+ call bar
+ .endr
+.align 2
+.L1:
+ .uleb128 .L1 - .L0
+ .uleb128 .L2 - .L0
+.L2:
+.align 2
+bar:
+ nop
--
2.17.0
next prev parent reply other threads:[~2020-01-22 7:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-27 8:12 Kuan-Lin Chen
2019-11-27 10:36 ` Andreas Schwab
2019-12-02 1:18 ` Kuan-Lin Chen
2019-12-02 22:27 ` Jim Wilson
2019-12-06 23:48 ` Palmer Dabbelt via binutils
2019-12-10 5:43 ` Kuan-Lin Chen
2019-12-17 23:59 ` Jim Wilson
2019-12-18 1:50 ` Nelson Chu
2020-01-06 8:18 ` Kuan-Lin Chen
2020-01-06 8:37 ` Kito Cheng
2020-01-06 8:44 ` Kuan-Lin Chen
2020-01-09 23:20 ` Palmer Dabbelt via binutils
2020-01-22 7:26 ` Kuan-Lin Chen [this message]
2020-09-25 7:14 ` Kito Cheng
2020-09-25 15:55 ` Jozef Lawrynowicz
2020-09-01 12:56 Jozef Lawrynowicz
2020-09-02 1:29 ` Kuan-Lin Chen
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