From: Xi Ruoyao <xry111@xry111.site>
Date: Mon, 12 Aug 2024 10:23:46 +0000 (+0800)
Subject: LoongArch: Fix assertion failure with DT_RELR
X-Git-Tag: gdb-16-branchpoint~1143
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=91e0b4655109a38b631baba310cb93a49f94c434;p=thirdparty%2Fbinutils-gdb.git

LoongArch: Fix assertion failure with DT_RELR

In the DT_RELR implementation I missed a code path emiting relative
reloc entries.  Then the already packed relative reloc entries will be
(unnecessarily) pushed into .rela.dyn but we've not allocated the space
for them, triggering an assertion failure.

Unfortunately I failed to notice the issue until profiled bootstrapping
GCC with LTO and -Wl,-z,pack-relative-relocs.  The failure can be easily
triggered by linking a "hello world" program with -fprofile-generate and
LTO:

    $ PATH=$HOME/ld-test:$PATH gcc hw.c -fprofile-generate -Wl,-z,pack-relative-relocs -flto
    /home/xry111/git-repos/binutils-build/TEST/ld: BFD (GNU Binutils) 2.43.50.20240802 assertion fail ../../binutils-gdb/bfd/elfnn-loongarch.c:2628
    /home/xry111/git-repos/binutils-build/TEST/ld: BFD (GNU Binutils) 2.43.50.20240802 assertion fail ../../binutils-gdb/bfd/elfnn-loongarch.c:2628
    collect2: error: ld returned 1 exit status

And the reduced test case is just incredibly simple (included in the
patch) so it seems I'm just stupid enough to fail to detect it before.
Let's fix it now anyway.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index af8cb2575e7..eecf7a800e8 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -4131,7 +4131,8 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 							    bfd_link_pic (info),
 							    h)
 			  && bfd_link_pic (info)
-			  && LARCH_REF_LOCAL (info, h))
+			  && LARCH_REF_LOCAL (info, h)
+			  && !info->enable_dt_relr)
 			{
 			  Elf_Internal_Rela rela;
 			  rela.r_offset = sec_addr (got) + got_off;
diff --git a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
index 16d89cd5a43..d80014d9563 100644
--- a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
+++ b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
@@ -161,6 +161,7 @@ if [istarget "loongarch64-*-*"] {
     run_dump_test "relr-data-pie"
     run_dump_test "relr-discard-pie"
     run_dump_test "relr-got-pie"
+    run_dump_test "relr-got-start"
     run_dump_test "relr-text-pie"
     run_dump_test "abssym_pie"
   }
diff --git a/ld/testsuite/ld-loongarch-elf/relr-got-start.d b/ld/testsuite/ld-loongarch-elf/relr-got-start.d
new file mode 100644
index 00000000000..0b1a5b9810d
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relr-got-start.d
@@ -0,0 +1,7 @@
+#source: relr-got-start.s
+#ld: -pie -z pack-relative-relocs -T relr-relocs.ld
+#readelf: -rW
+
+Relocation section '\.relr\.dyn' at offset 0x[a-z0-f]+ contains 1 entry which relocates 1 location:
+Index: Entry            Address           Symbolic Address
+0000:  0000000000020008 0000000000020008  _GLOBAL_OFFSET_TABLE_ \+ 0x8
diff --git a/ld/testsuite/ld-loongarch-elf/relr-got-start.s b/ld/testsuite/ld-loongarch-elf/relr-got-start.s
new file mode 100644
index 00000000000..c89fb42527f
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relr-got-start.s
@@ -0,0 +1,5 @@
+.globl _start
+_start:
+        pcalau12i       $r5,%got_pc_hi20(_start)
+        ld.d    $r5,$r5,%got_pc_lo12(_start)
+        ret