4 Commits

Author SHA1 Message Date
Fangrui Song
1da4f47195 [yaml2obj] Set p_align to the maximum sh_addralign of contained sections
The address difference between two sections in a PT_LOAD is a constant.
Consider a hypothetical case (pagesize can be very small, say, 4).

```
.text     sh_addralign=4
.text.hot sh_addralign=16
```

If we set p_align to 4, the PT_LOAD will be loaded at an address which
is a multiple of 4. The address of .text.hot is guaranteed to be a
multiple of 4, but not necessarily a multiple of 16.

This patch deletes the constraint

  if (SHeader->sh_offset == PHeader.p_offset)

Reviewed By: grimar, jhenderson

Differential Revision: https://reviews.llvm.org/D67260

llvm-svn: 371501
2019-09-10 09:16:34 +00:00
Fangrui Song
c3bc697974 [yaml2obj] Write the section header table after section contents
Linkers (ld.bfd/gold/lld) place the section header table at the very
end. This allows tools to strip it, which is optional in executable/shared objects.
In addition, if we add or section, the size of the section header table
will change. Placing the section header table in the end keeps section
offsets unchanged.

yaml2obj currently places the section header table immediately after the
program header. Follow what linkers do to make offset updating easier.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D67221

llvm-svn: 371074
2019-09-05 14:25:57 +00:00
Fangrui Song
e29e30b139 [llvm-readobj] Change -long-option to --long-option in tests. NFC
We use both -long-option and --long-option in tests. Switch to --long-option for consistency.

In the "llvm-readelf" mode, -long-option is discouraged as it conflicts with grouped short options and it is not accepted by GNU readelf.

While updating the tests, change llvm-readobj -s to llvm-readobj -S to reduce confusion ("s" is --section-headers in llvm-readobj but --symbols in llvm-readelf).

llvm-svn: 359649
2019-05-01 05:27:20 +00:00
Jake Ehrlich
03aeeb09c5 [yaml2obj][ELF] Add support for setting alignment in program headers
Sometimes program headers have larger alignments than any of the
sections they contain. Currently yaml2obj can't produce such files. A
bug recently appeared in llvm-objcopy that failed in such a case. I'd
like to be able to add tests to llvm-objcopy for such cases.

This change adds an optional alignment parameter to program headers that
will be used instead of calculating the alignment.

Differential Revision: https://reviews.llvm.org/D39130

llvm-svn: 317139
2017-11-01 23:14:48 +00:00