Summary:
Currently when --no-rosegment is specified or a linker script with SECTIONS command is used,
.rodata (A) .text (AX) are assigned the same rank and .rodata may be placed after .text .
This increases the gap between .text and .bss and can cause pc-relative relocation overflow (e.g. gcc crtbegin.o crtbegin.S have R_X86_64_PC32 relocation from .text to .bss).
This patch makes SingleRoRx affect only segment layout, not section layout. As a consequence, .rodata will be placed before .text regardless of SingleRoRx.
Reviewers: espindola, ruiu, grimar, echristo, javed.absar
Subscribers: emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D48405
llvm-svn: 335627
This CL places .dynsym and .dynstr at the beginning of SHF_ALLOC
sections. We do this to mitigate the possibility that huge .dynsym and
.dynstr sections placed between ro-data and text sections cause
relocation overflow.
Differential Revision: https://reviews.llvm.org/D45788
llvm-svn: 332374
This CL is to mitigate R_X86_64_PC32 relocation overflow problems for huge binaries that has near 4G allocated sections.
By examining those binaries, there're 2 issues contributes to the problem:
1). huge ".dynsym" and ".dynstr" stands in the way between .rodata and .text
2). _init_array_start/end are placed at 0 if no ".init_array" presents, this causes .text relocation against them become more prone to overflow.
This CL addresses 1st problem (the 2nd will be addressed in another CL.) by assigning a smaller sortrank to .dynsym and .dynstr thus they no longer stand in between.
llvm-svn: 332038
Its PR34712,
GNU linkers recently changed default values to "both" of "sysv".
Patch do the same for all targets except MIPS, where .gnu.hash
section is not yet supported.
Code suggested by Rui Ueyama.
Differential revision: https://reviews.llvm.org/D38407
llvm-svn: 315051
The default padding for an executable segment is the target trap
instruction which for x86_64 is 0xCC. However, the .eh_frame section
requires the padding to be zero. The code that writes the .eh_frame
section assumes that its segment is zero initialized and does not
explicitly write the zero padding. This does not work when the .eh_frame
section is in the executable segment (for example when using
-no-rosegment).
This patch changes the .eh_frame writing code to explicitly write the
zero padding.
Differential Revision: https://reviews.llvm.org/D37462
llvm-svn: 312706
Fangrui Song