about summary refs log tree commit diff
path: root/configure.ac
diff options
context:
space:
mode:
authorFangrui Song <maskray@google.com>2022-03-08 17:17:05 -0800
committerFangrui Song <maskray@google.com>2022-03-08 17:17:05 -0800
commit1c6cc29baf9a4c7129ab2e94b0d4022bfa4f3299 (patch)
tree008312335cd84ecfcc73c38b72ba836d06e3ca2f /configure.ac
parentedc696a73a7cb07b1aa68792a845a98d036ee7eb (diff)
downloadglibc-1c6cc29baf9a4c7129ab2e94b0d4022bfa4f3299.tar.gz
glibc-1c6cc29baf9a4c7129ab2e94b0d4022bfa4f3299.tar.xz
glibc-1c6cc29baf9a4c7129ab2e94b0d4022bfa4f3299.zip
elf: Support DT_RELR relative relocation format [BZ #27924] maskray/relr
PIE and shared objects usually have many relative relocations. In
2017/2018, SHT_RELR/DT_RELR was proposed on
https://groups.google.com/g/generic-abi/c/bX460iggiKg/m/GxjM0L-PBAAJ
("Proposal for a new section type SHT_RELR") and is a pre-standard. RELR
usually takes 3% or smaller space than R_*_RELATIVE relocations. The
virtual memory size of a mostly statically linked PIE is typically 5~10%
smaller.

This patch adds ELF_DYNAMIC_DO_RELR to ELF_DYNAMIC_RELOCATE.
ELF_DYNAMIC_DO_RELR is ordered before ELF_DYNAMIC_DO_REL[A] so that ifunc
resolvers that require relocated got entries have them relocated. This is
needed for ppc64 according to Alan Modra.
Diffstat (limited to 'configure.ac')
-rw-r--r--configure.ac4
1 files changed, 4 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac
index 87f67d25ec..d6bb323fa6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1367,6 +1367,10 @@ LIBC_LINKER_FEATURE([--depaudit], [-Wl,--depaudit,x],
 		    [libc_cv_depaudit=yes], [libc_cv_depaudit=no])
 LIBC_CONFIG_VAR([have-depaudit], [$libc_cv_depaudit])
 
+LIBC_LINKER_FEATURE([-z pack-relative-relocs], [-Wl,-z,pack-relative-relocs],
+		    [libc_cv_relr=yes], [libc_cv_relr=no])
+LIBC_CONFIG_VAR([have-relr], [$libc_cv_relr])
+
 LIBC_LINKER_FEATURE([--no-dynamic-linker],
 		    [-Wl,--no-dynamic-linker],
 		    [libc_cv_no_dynamic_linker=yes],