Commit Graph

8 Commits

Author SHA1 Message Date
Fangrui Song 71e2ca6e32 [llvm-objdump] -d: print `00000000 <foo>:` instead of `00000000 foo:`
The new behavior matches GNU objdump. A pair of angle brackets makes tests slightly easier.

`.foo:` is not unique and thus cannot be used in a `CHECK-LABEL:` directive.
Without `-LABEL`, the CHECK line can match the `Disassembly of section`
line and causes the next `CHECK-NEXT:` to fail.

```
Disassembly of section .foo:

0000000000001634 .foo:
```

Bdragon: <> has metalinguistic connotation. it just "feels right"

Reviewed By: rupprecht

Differential Revision: https://reviews.llvm.org/D75713
2020-03-05 18:05:28 -08:00
Fangrui Song 9c371309f3 [ELF][X86] Allow PT_LOAD to have overlapping p_offset ranges on EM_386
Ported the D64906 technique to EM_386.

If `sh_addralign(.tdata) < sh_addralign(.tbss)`,
we can potentially make `p_vaddr(PT_TLS)%p_align(PT_TLS) != 0`.

ld.so that are known to have problems if p_vaddr%p_align!=0:

* FreeBSD 13.0-CURRENT rtld-elf
* glibc https://sourceware.org/bugzilla/show_bug.cgi?id=24606

New test i386-tls-vaddr-align.s checks our workaround makes p_vaddr%p_align = 0.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D65865

llvm-svn: 369347
2019-08-20 08:43:47 +00:00
Fangrui Song 5387c2cd17 [llvm-objdump] Print newlines before and after "Disassembly of section ...:"
This improves readability and the behavior is consistent with GNU objdump.

The new test test/tools/llvm-objdump/X86/disassemble-section-name.s
checks we print newlines before and after "Disassembly of section ...:"

Differential Revision: https://reviews.llvm.org/D61127

llvm-svn: 359668
2019-05-01 10:40:48 +00:00
Fangrui Song b159906a9a [test] Change llvm-readobj -long-option to --long-option or well-known short options. NFC
Also change some options that have different semantics (cause confusion) in llvm-readelf mode:

-s => -S
-t => --symbols
-sd => --section-data

llvm-svn: 359651
2019-05-01 05:49:01 +00:00
Fangrui Song 210949a221 [ELF] Change GOT*_FROM_END (relative to end(.got)) to GOTPLT* (start(.got.plt))
Summary:
This should address remaining issues discussed in PR36555.

Currently R_GOT*_FROM_END are exclusively used by x86 and x86_64 to
express relocations types relative to the GOT base. We have
_GLOBAL_OFFSET_TABLE_ (GOT base) = start(.got.plt) but end(.got) !=
start(.got.plt)

This can have problems when _GLOBAL_OFFSET_TABLE_ is used as a symbol, e.g.
glibc dl_machine_dynamic assumes _GLOBAL_OFFSET_TABLE_ is start(.got.plt),
which is not true.

  extern const ElfW(Addr) _GLOBAL_OFFSET_TABLE_[] attribute_hidden;
  return _GLOBAL_OFFSET_TABLE_[0]; // R_X86_64_GOTPC32

In this patch, we

* Change all GOT*_FROM_END to GOTPLT* to fix the problem.
* Add HasGotPltOffRel to denote whether .got.plt should be kept even if
  the section is empty.
* Simplify GotSection::empty and GotPltSection::empty by setting
  HasGotOffRel and HasGotPltOffRel according to GlobalOffsetTable early.

The change of R_386_GOTPC makes X86::writePltHeader simpler as we don't
have to compute the offset start(.got.plt) - Ebx (it is constant 0).

We still diverge from ld.bfd (at least in most cases) and gold in that
.got.plt and .got are not adjacent, but the advantage doing that is
unclear.

Reviewers: ruiu, sivachandra, espindola

Subscribers: emaste, mehdi_amini, arichardson, dexonsmith, jdoerfert, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59594

llvm-svn: 356968
2019-03-25 23:46:19 +00:00
Dimitry Andric c9de3b4d26 Align AArch64 and i386 image base to superpage
Summary:

As for x86_64, the default image base for AArch64 and i386 should be
aligned to a superpage appropriate for the architecture.

On AArch64, this is 2 MiB, on i386 it is 4 MiB.

Reviewers: emaste, grimar, javed.absar, espindola, ruiu, peter.smith, srhines, rprichard

Reviewed By: ruiu, peter.smith

Subscribers: jfb, markj, arichardson, krytarowski, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D50297

llvm-svn: 342746
2018-09-21 16:58:13 +00:00
Fangrui Song b6772b86e2 [ELF] Move `// REQUIRES:` line to the top
llvm-svn: 335676
2018-06-26 22:20:04 +00:00
George Rimar bfb7bf7429 [ELF] - R_386_GOTOFF relocation implemented.
R_386_GOTOFF is calculated as S + A - GOT, where:
S - Represents the value of the symbol whose index resides in the relocation entry.
A - Represents the addend used to compute the value of the relocatable field.
GOT - Represents the address of the global offset table.

Differential revision: http://reviews.llvm.org/D15383

llvm-svn: 256143
2015-12-21 10:00:12 +00:00