commit cb19cef087eaa551568739aa5b59cf97b8d5da1e
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Jul 16 07:57:45 2024 -0300

    elf: Fix localplt.awk for DT_RELR-enabled builds (BZ 31978)
    
    For each input readelf output, localplt.awk parses each 'Relocation
    section' entry, checks its offset against the dynamic section entry, and
    saves each DT_JMPREL, DT_RELA, and DT_REL offset value it finds. After
    all lines are read, the script checks if any segment offset differed
    from 0, meaning at least one 'Relocation section' was matched.
    
    However, if the shared object was built with RELR support and the static
    linker could place all the relocation on DT_RELR, there would be no
    DT_JMPREL, DT_RELA, and DT_REL entries; only a DT_RELR.
    
    For the current three ABIs that support (aarch64, x86, and powerpc64),
    the powerpc64 ld.so shows the behavior above. Both x86_64 and aarch64
    show extra relocations on '.rela.dyn', which makes the script check to
    succeed.
    
    This patch fixes by handling DT_RELR, where the offset is checked
    against the dynamic section entries and if the shared object contains an
    entry it means that there are no extra PLT entries (since all
    relocations are relative).
    
    It fixes the elf/check-localplt failure on powerpc.
    
    Checked with a build/check for aarch64-linux-gnu, x86_64-linux-gnu,
    i686-linux-gnu, arm-linux-gnueabihf, s390x-linux-gnu, powerpc-linux-gnu,
    powerpc64-linux-gnu, and powerpc64le-linux-gnu.
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    
    (cherry picked from commit 4f047d9edecb1a9b796a9a904dcd42bd3cc3d3b6)

diff --git a/scripts/localplt.awk b/scripts/localplt.awk
index fe79ca01abcb1a75..621ae7d8e815a4e5 100644
--- a/scripts/localplt.awk
+++ b/scripts/localplt.awk
@@ -10,7 +10,8 @@ BEGIN {
 }
 
 FILENAME != lastfile {
-  if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) {
+  if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0 \
+      && relr_offset == 0) {
     print FILENAME ": *** failed to find expected output (readelf -WSdr)";
     result = 2;
   }
@@ -22,6 +23,7 @@ FILENAME != lastfile {
   jmprel_offset = 0;
   rela_offset = 0;
   rel_offset = 0;
+  relr_offset = 0;
   pltrelsz = -1;
   delete section_offset_by_address;
 }
@@ -77,6 +79,8 @@ in_relocs && relocs_offset == rel_offset && NF >= 5 {
   }
 }
 
+# No need to handle DT_RELR (all packed relocations are relative).
+
 in_relocs { next }
 
 $1 == "Relocation" && $2 == "section" && $5 == "offset" {
@@ -121,4 +125,14 @@ $2 == "(REL)" {
   }
   next
 }
+
+$2 == "(RELR)" {
+  relr_addr = strtonum($3);
+  if (relr_addr in section_offset_by_address) {
+    relr_offset = section_offset_by_address[relr_addr];
+  } else {
+    print FILENAME ": *** DT_RELR does not match any section's address";
+    result = 2;
+  }
+}
 END { exit(result) }