From: Fangrui Song <maskray@google.com>
Date: Thu, 23 Jun 2022 08:10:44 +0000 (-0700)
Subject: aarch64: Allow PC-relative relocations against protected STT_FUNC for -shared
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=83c325007c5599fa9b60b8d5f7b84842160e1d1b;p=binutils-gdb.git

aarch64: Allow PC-relative relocations against protected STT_FUNC for -shared

    __attribute__((visibility("protected"))) void *foo() {
      return (void *)foo;
    }

gcc -fpic -shared -fuse-ld=bfd fails with the confusing diagnostic:

    relocation R_AARCH64_ADR_PREL_PG_HI21 against symbol `foo' which may bind externally can not be used when making a shared object; recompile with -fPIC

Call _bfd_elf_symbol_refs_local_p with local_protected==true to suppress
the error.  The new behavior matches gold and ld.lld.

Note: if some code tries to use direct access relocations to take the
address of foo (likely due to -fno-pic), the pointer equality will
break, but the error should be reported on the executable link, not on
the innocent shared object link.  glibc 2.36 will give a warning at
relocation resolving time.
---

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index ce2632ecd30..c688b7cff2d 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -5888,7 +5888,7 @@ elfNN_aarch64_final_link_relocate (reloc_howto_type *howto,
       if (bfd_link_pic (info)
 	  && (input_section->flags & SEC_ALLOC) != 0
 	  && (input_section->flags & SEC_READONLY) != 0
-	  && !SYMBOL_REFERENCES_LOCAL (info, h))
+	  && !_bfd_elf_symbol_refs_local_p (h, info, 1))
 	{
 	  int howto_index = bfd_r_type - BFD_RELOC_AARCH64_RELOC_START;
 
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 31162277bd9..3c45f87151f 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -248,6 +248,7 @@ run_dump_test_lp64 "local-addend-r"
 # test error handling on pcrel relocation for shared libraries.
 run_dump_test_lp64 "pcrel_pic_undefined"
 run_dump_test_lp64 "pcrel_pic_defined"
+run_dump_test_lp64 "pcrel_pic_protected"
 
 run_dump_test "limit-b"
 run_dump_test "limit-bl"
diff --git a/ld/testsuite/ld-aarch64/pcrel-protected.s b/ld/testsuite/ld-aarch64/pcrel-protected.s
new file mode 100644
index 00000000000..24c6232ca19
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/pcrel-protected.s
@@ -0,0 +1,11 @@
+.protected protected_a, protected_b, protected_c
+.type protected_b, %object
+.type protected_c, %function
+
+.text
+	adrp    x0, protected_a
+	add     x0, x0, :lo12:protected_a
+	adrp    x0, protected_b
+	add     x0, x0, :lo12:protected_b
+	adrp    x0, protected_c
+	add     x0, x0, :lo12:protected_c
diff --git a/ld/testsuite/ld-aarch64/pcrel_pic_protected.d b/ld/testsuite/ld-aarch64/pcrel_pic_protected.d
new file mode 100644
index 00000000000..1b6f24cf2fb
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/pcrel_pic_protected.d
@@ -0,0 +1,7 @@
+#name: PC-Rel relocation against protected
+#source: pcrel-protected.s
+#target: [check_shared_lib_support]
+#ld: -shared -e0 --defsym protected_a=0x1000 --defsym protected_b=0x1010 --defsym protected_c=0x1020
+#readelf: -r -W
+#...
+There are no relocations in this file.