See http://lists.llvm.org/pipermail/llvm-dev/2020-April/140549.html
For the record, GNU ld changed to 64k max page size in 2014
https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=7572ca8989ead4c3425a1500bc241eaaeffa2c89
"[RFC] ld/ARM: Increase maximum page size to 64kB"
Android driver forced 4k page size in AArch64 (D55029) and ARM (D77746).
A binary linked with max-page-size=4096 does not run on a system with a
higher page size configured. There are some systems out there that do
this and it leads to the binary getting `Killed!` by the kernel.
In the non-linker-script cases, when linked with -z noseparate-code
(default), the max-page-size increase should not cause any size
difference. There may be some VMA usage differences, though.
Reviewed By: psmith, MaskRay
Differential Revision: https://reviews.llvm.org/D77330
Port the D64906 technique to ARM. It deletes 3 alignments at
PT_LOAD boundaries for the default case: the size of an arm binary
decreases by at most 12kb.
Reviewed By: grimar
Differential Revision: https://reviews.llvm.org/D66749
llvm-svn: 370049
Old: PT_LOAD(.data | PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .bss)
New: PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss)
The placement of | indicates page alignment caused by PT_GNU_RELRO. The
new layout has simpler rules and saves space for many cases.
Old size: roundup(.data) + roundup(.data.rel.ro)
New size: roundup(.data.rel.ro + .bss.rel.ro) + .data
Other advantages:
* At runtime the 3 memory mappings decrease to 2.
* start(PT_TLS) = start(PT_GNU_RELRO) = start(RW PT_LOAD). This
simplifies binary manipulation tools.
GNU strip before 2.31 discards PT_GNU_RELRO if its
address is not equal to the start of its associated PT_LOAD.
This has been fixed by https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f2731e0c374e5323ce4cdae2bcc7b7fe22da1a6f
But with this change, we will be compatible with GNU strip before 2.31
* Before, .got.plt (non-relro by default) was placed before .got (relro
by default), which made it impossible to have _GLOBAL_OFFSET_TABLE_
(start of .got.plt on x86-64) equal to the end of .got (R_GOT*_FROM_END)
(https://bugs.llvm.org/show_bug.cgi?id=36555). With the new ordering, we
can improve on this regard if we'd like to.
Reviewers: ruiu, espindola, pcc
Subscribers: emaste, arichardson, llvm-commits, joerg, jdoerfert
Differential Revision: https://reviews.llvm.org/D56828
llvm-svn: 356117
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
This is in preparation for my next change, which will introduce a relro
nobits section. That requires that relro sections appear at the end of the
progbits part of the r/w segment so that the relro nobits section can appear
contiguously.
Because of the amount of churn required in the test suite, I'm making this
change separately.
llvm-svn: 291523
When compiling -fpie and linking with the --pie option the R_ARM_GOTBREL
relocation to D is resolved by writing the value of D into the .got slot
and emitting an R_ARM_RELATIVE relocation for it.
This changes adds the R_ARM_RELATIVE relocation to the switch in
relocateOne() so we can process the GotSection relocation to write the
value of the variable as well as emitting the dynamic relocation.
Differential revision: https://reviews.llvm.org/D27678
llvm-svn: 289527
Fangrui Song