Re: PowerPC64 DT_RELR

[Alan Modra <amodra@gmail.com>]

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I had a look today at DT_RELR again, and found I need to do some work
in the linker.  Just keeping addresses of relative relocs isn't
enough, because data addresses can change between ppc64_elf_size_stubs
and ppc64_elf_build_stubs.  Anyway, the reason for the email is to
inform anyone playing with DT_RELR on powerpc64 that the current
support is definitely experimental!  Also, you might like to apply the
attached patch to gitlab.com/x86-glibc/glibc users/hjl/relr/master
branch.  glibc regressions went from 574 to 17.

-- 
Alan Modra
Australia Development Lab, IBM

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From 59265b9b769a0423700bd5a34bc9933e859e51c2 Mon Sep 17 00:00:00 2001
From: Alan Modra <amodra@gmail.com>
Date: Wed, 2 Mar 2022 15:34:58 +1030
Subject: [PATCH 6/6] elf: ELF_DYNAMIC_RELOCATE: order relr before rel/rela

ld goes to some trouble to sort relative relocs first, so that ifunc
resolvers that require relocated got entries have them relocated.
Preserve that ordering.

diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
index 320a9029f2..252f407a12 100644
--- a/elf/dynamic-link.h
+++ b/elf/dynamic-link.h
@@ -188,10 +188,10 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
   do {									      \
     int edr_lazy = elf_machine_runtime_setup ((map), (scope), (lazy),	      \
 					      (consider_profile));	      \
-    ELF_DYNAMIC_DO_REL ((map), (scope), edr_lazy, skip_ifunc);		      \
-    ELF_DYNAMIC_DO_RELA ((map), (scope), edr_lazy, skip_ifunc);		      \
     if (((map) != &GL(dl_rtld_map) || DO_RTLD_BOOTSTRAP))		      \
       ELF_DYNAMIC_DO_RELR (map);					      \
+    ELF_DYNAMIC_DO_REL ((map), (scope), edr_lazy, skip_ifunc);		      \
+    ELF_DYNAMIC_DO_RELA ((map), (scope), edr_lazy, skip_ifunc);		      \
   } while (0)
 
 #endif