commit 72ec930fa7 added basic support for
relocations, but assumed that the symbol value would be 0, likely because
.debug_info always has address == 0 in the ELF section headers.
CL 195679 added further support for relocations, but explicitly encoded
the original assumption that section addresses would be 0.
This change removes that assumption: all relocations will now be
properly computed based on the target symbol value even when that symbol
is a section with a non-zero address.
Typically, sections that are part of a LOAD program segment have
non-zero addresses. For example, .debug_ranges relocations could be
relative to .text, which usually has an address > 0.
Fixes#40879
Change-Id: Ib0a616bb8b05d6c96d179b03ca33a10946fc5d59
GitHub-Last-Rev: 4200de7326
GitHub-Pull-Request: golang/go#41038
Reviewed-on: https://go-review.googlesource.com/c/go/+/250559
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Based on the code from https://github.com/riscv/riscv-go/ originally
written by Amol Bhave.
Change-Id: I8d5377096d4ff8b198dadb630511f9a0347f9797
Reviewed-on: https://go-review.googlesource.com/107339
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This adds support for compressed ELF sections. This compression is
treated as a framing issue and hence the package APIs all
transparently decompress compressed sections. This requires some
subtlety for (*Section).Open, which returns an io.ReadSeeker: since
the decompressed data comes from an io.Reader, this commit introduces
a Reader-to-ReadSeeker adapter that is efficient for common uses of
Seek and does what it can otherwise.
Fixes#11773.
Change-Id: Ic0cb7255a85cadf4c1d15fb563d5a2e89dbd3c36
Reviewed-on: https://go-review.googlesource.com/17341
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
GCC and LLVM support zlib-compressing DWARF debug sections (and
there's some evidence that this may be happening by default in some
circumstances now).
Add support for reading compressed DWARF sections. Since ELF
relocations apply to the decompressed data, decompression is done
before applying relocations. Since relcations are applied by
debug/elf, decompression must also be handled there.
Note that this is different from compressed ELF sections, which is a
more general mechanism used by very recent versions of GCC.
Updates #11773.
Change-Id: I3f4bf1b04d0802cc1e8fcb7c2a5fcf6c467c5089
Reviewed-on: https://go-review.googlesource.com/17340
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
The original version of applyRelocationsARM was added in
http://golang.org/cl/7266. It was added to fix the ARM build, which
had been broken by http://golang.org/cl/6780.
Before CL 6780, there was no relocation processing for ARM. CL 6780
changed the code to require relocation processing for every supported
target. CL 7266 fixed the ARM build by adding a relocation processing
function, but in fact no actual processing was done. The code only
looked for REL32 relocations, but ARM debug info has no such
relocations. The test case added in CL 7266 doesn't have any either.
This didn't matter because no relocation processing was required on
ARM, at least not for GCC-generated debug info. GCC generates ABS32
relocations, but only against section symbols which have the value 0.
Therefore, the addition done by correct handling of ABS32 doesn't
change anything.
Clang, however, generates ABS32 relocations against local symbols,
some of which have non-zero values. For those, we need to handle
ABS32 relocations.
This patch corrects the CL 7266 to look for ABS32 relocations instead
of REL32 relocations. The code was already written to correctly
handle ABS32 relocations, it just mistakenly said REL32.
This is the ARM equivalent of https://golang.org/cl/96680045, which
fixed the same problem in the same way for clang on 386.
With this patch, clang-3.5 can be used to build Go on ARM GNU/Linux.
Fixes#8980.
Change-Id: I0c2d72eadfe6373bde99cd03eee40de6a582dda1
Reviewed-on: https://go-review.googlesource.com/11222
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
This change adds the minimum necessary to implement applyRelocations.
For adg, this code uses the switch statement.
Change-Id: I0989daab8d0e36c2a4f6a315ced258b832744616
Reviewed-on: https://go-review.googlesource.com/7266
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This also removes pkg/runtime/traceback_lr.c, which was ported
to Go in an earlier commit and then moved to
runtime/traceback.go.
Reviewer: rsc@golang.org
rsc: LGTM
Victor Michel
Tobias Klauser
Vladimir Stefanovic
James Clarke
Michael Munday
Caleb Spare
Austin Clements
Yao Zhang
Andrew Gerrand
Ian Lance Taylor
Dave Cheney
Russ Cox