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From 601d68c3a9866761ca19d1c27186f30de68a7af5 Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <[email protected]>
Date: Sun, 30 Jun 2024 15:18:22 +0800
Subject: [PATCH 096/123] LoongArch: Fix bad reloc with mixed visibility ifunc
symbols in shared libraries
With a simple test case:
.globl ifunc
.globl ifunc_hidden
.hidden ifunc_hidden
.type ifunc, %gnu_indirect_function
.type ifunc_hidden, %gnu_indirect_function
.text
.align 2
ifunc: ret
ifunc_hidden: ret
test:
bl ifunc
bl ifunc_hidden
"ld -shared" produces a shared object with one R_LARCH_NONE (instead of
R_LARCH_JUMP_SLOT as we expect) to relocate the GOT entry of "ifunc".
It's because the indices in .plt and .rela.plt mismatches for
STV_DEFAULT STT_IFUNC symbols when another PLT entry exists for a
STV_HIDDEN STT_IFUNC symbol, and such a mismatch breaks the logic of
loongarch_elf_finish_dynamic_symbol. Fix the issue by reordering .plt
so the indices no longer mismatch.
Signed-off-by: Xi Ruoyao <[email protected]>
---
bfd/elfnn-loongarch.c | 77 ++++++++++++++++---
ld/testsuite/ld-loongarch-elf/ifunc-reloc.d | 19 +++++
ld/testsuite/ld-loongarch-elf/ifunc-reloc.s | 55 +++++++++++++
.../ld-loongarch-elf/ld-loongarch-elf.exp | 1 +
4 files changed, 140 insertions(+), 12 deletions(-)
create mode 100644 ld/testsuite/ld-loongarch-elf/ifunc-reloc.d
create mode 100644 ld/testsuite/ld-loongarch-elf/ifunc-reloc.s
diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index fa0a5e38..6b1a4ecc 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -1716,9 +1716,10 @@ local_allocate_ifunc_dyn_relocs (struct bfd_link_info *info,
ifunc dynamic relocs. */
static bool
-elfNN_allocate_ifunc_dynrelocs (struct elf_link_hash_entry *h, void *inf)
+elfNN_allocate_ifunc_dynrelocs (struct elf_link_hash_entry *h,
+ struct bfd_link_info *info,
+ bool ref_local)
{
- struct bfd_link_info *info;
/* An example of a bfd_link_hash_indirect symbol is versioned
symbol. For example: __gxx_personality_v0(bfd_link_hash_indirect)
-> __gxx_personality_v0(bfd_link_hash_defined)
@@ -1734,20 +1735,18 @@ elfNN_allocate_ifunc_dynrelocs (struct elf_link_hash_entry *h, void *inf)
if (h->root.type == bfd_link_hash_warning)
h = (struct elf_link_hash_entry *) h->root.u.i.link;
- info = (struct bfd_link_info *) inf;
-
/* Since STT_GNU_IFUNC symbol must go through PLT, we handle it
here if it is defined and referenced in a non-shared object. */
if (h->type == STT_GNU_IFUNC && h->def_regular)
{
- if (SYMBOL_REFERENCES_LOCAL (info, h))
+ if (ref_local && SYMBOL_REFERENCES_LOCAL (info, h))
return local_allocate_ifunc_dyn_relocs (info, h,
&h->dyn_relocs,
PLT_ENTRY_SIZE,
PLT_HEADER_SIZE,
GOT_ENTRY_SIZE,
false);
- else
+ else if (!ref_local && !SYMBOL_REFERENCES_LOCAL (info, h))
return _bfd_elf_allocate_ifunc_dyn_relocs (info, h,
&h->dyn_relocs,
PLT_ENTRY_SIZE,
@@ -1759,6 +1758,23 @@ elfNN_allocate_ifunc_dynrelocs (struct elf_link_hash_entry *h, void *inf)
return true;
}
+static bool
+elfNN_allocate_ifunc_dynrelocs_ref_local (struct elf_link_hash_entry *h,
+ void *info)
+{
+ return elfNN_allocate_ifunc_dynrelocs (h, (struct bfd_link_info *) info,
+ true);
+}
+
+static bool
+elfNN_allocate_ifunc_dynrelocs_ref_global (struct elf_link_hash_entry *h,
+ void *info)
+{
+ return elfNN_allocate_ifunc_dynrelocs (h, (struct bfd_link_info *) info,
+ false);
+}
+
+
/* Allocate space in .plt, .got and associated reloc sections for
ifunc dynamic relocs. */
@@ -1774,7 +1790,7 @@ elfNN_allocate_local_ifunc_dynrelocs (void **slot, void *inf)
|| h->root.type != bfd_link_hash_defined)
abort ();
- return elfNN_allocate_ifunc_dynrelocs (h, inf);
+ return elfNN_allocate_ifunc_dynrelocs_ref_local (h, inf);
}
/* Set DF_TEXTREL if we find any dynamic relocs that apply to
@@ -1933,11 +1949,48 @@ loongarch_elf_size_dynamic_sections (bfd *output_bfd,
sym dynamic relocs. */
elf_link_hash_traverse (&htab->elf, allocate_dynrelocs, info);
- /* Allocate global ifunc sym .plt and .got entries, and space for global
- ifunc sym dynamic relocs. */
- elf_link_hash_traverse (&htab->elf, elfNN_allocate_ifunc_dynrelocs, info);
-
- /* Allocate .plt and .got entries, and space for local ifunc symbols. */
+ /* Allocate global ifunc sym .plt and .got entries, and space for
+ *preemptible* ifunc sym dynamic relocs. Note that we must do it
+ for *all* preemptible ifunc (including local ifuncs and STV_HIDDEN
+ ifuncs) before doing it for any non-preemptible ifunc symbol:
+ assuming we are not so careful, when we link a shared library the
+ correlation of .plt and .rela.plt might look like:
+
+ idx in .plt idx in .rela.plt
+ ext_func1@plt 0 0
+ ext_func2@plt 1 1
+ ext_func3@plt 2 2
+ hidden_ifunc1@plt 3 None: it's in .rela.got
+ hidden_ifunc2@plt 4 None: it's in .rela.got
+ normal_ifunc1@plt 5 != 3
+ normal_ifunc2@plt 6 != 4
+ local_ifunc@plt 7 None: it's in .rela.got
+
+ Now oops the indices for normal_ifunc{1,2} in .rela.plt were different
+ from the indices in .plt :(. This would break finish_dynamic_symbol
+ which assumes the index in .rela.plt matches the index in .plt.
+
+ So let's be careful and make it correct:
+
+ idx in .plt idx in .rela.plt
+ ext_func1@plt 0 0
+ ext_func2@plt 1 1
+ ext_func3@plt 2 2
+ normal_ifunc1@plt 3 3
+ normal_ifunc2@plt 4 4
+ hidden_ifunc1@plt 5 None: it's in .rela.got
+ hidden_ifunc2@plt 6 None: it's in .rela.got
+ local_ifunc@plt 7 None: it's in .rela.got
+
+ Now normal_ifuncs first. */
+ elf_link_hash_traverse (&htab->elf,
+ elfNN_allocate_ifunc_dynrelocs_ref_global, info);
+
+ /* Next hidden_ifuncs follows. */
+ elf_link_hash_traverse (&htab->elf,
+ elfNN_allocate_ifunc_dynrelocs_ref_local, info);
+
+ /* Finally local_ifuncs. */
htab_traverse (htab->loc_hash_table,
elfNN_allocate_local_ifunc_dynrelocs, info);
diff --git a/ld/testsuite/ld-loongarch-elf/ifunc-reloc.d b/ld/testsuite/ld-loongarch-elf/ifunc-reloc.d
new file mode 100644
index 00000000..cb592874
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/ifunc-reloc.d
@@ -0,0 +1,19 @@
+#ld: -shared
+#readelf: -Wr
+
+#...
+.*'\.rela\.dyn'.*
+#...
+.* R_LARCH_RELATIVE .*
+.* R_LARCH_IRELATIVE .*
+.* R_LARCH_IRELATIVE .*
+.* R_LARCH_IRELATIVE .*
+#...
+.*'\.rela\.plt'.*
+#...
+.* R_LARCH_JUMP_SLOT .*
+.* R_LARCH_JUMP_SLOT .*
+.* R_LARCH_JUMP_SLOT .*
+.* R_LARCH_JUMP_SLOT .*
+.* R_LARCH_JUMP_SLOT .*
+.* R_LARCH_JUMP_SLOT .*
diff --git a/ld/testsuite/ld-loongarch-elf/ifunc-reloc.s b/ld/testsuite/ld-loongarch-elf/ifunc-reloc.s
new file mode 100644
index 00000000..e59f2b20
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/ifunc-reloc.s
@@ -0,0 +1,55 @@
+.globl foo
+.globl foo_hidden1
+.globl foo_hidden2
+.globl foo_protected
+
+.type foo, %gnu_indirect_function
+.type foo_hidden1, %gnu_indirect_function
+.type foo_hidden2, %gnu_indirect_function
+.type foo_protected, %gnu_indirect_function
+.type foo_internal, %gnu_indirect_function
+
+.hidden foo_hidden1
+.hidden foo_hidden2
+
+.protected foo_protected
+
+.globl ext_ifunc1
+.globl ext_ifunc2
+.type ext_ifunc1, %gnu_indirect_function
+.type ext_ifunc2, %gnu_indirect_function
+
+.text
+.align 2
+foo:
+ ret
+
+foo_hidden1:
+ ret
+
+foo_hidden2:
+ ret
+
+foo_protected:
+ ret
+
+foo_internal:
+ ret
+
+test:
+ la.got $a0, num
+ # The order is deliberately shuffled.
+ bl ext_ifunc1
+ bl foo
+ bl foo_hidden1
+ bl ext_func1
+ bl foo_protected
+ bl foo_internal
+ bl foo_hidden2
+ bl ext_func2
+ bl ext_ifunc2
+
+.data
+.align 3
+num:
+ .quad 114514
diff --git a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
index 7ffabe2c..506dac3e 100644
--- a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
+++ b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
@@ -133,6 +133,7 @@ if [istarget "loongarch64-*-*"] {
run_dump_test "reloc_ler_with_shared"
run_dump_test "reloc_abs_with_shared"
run_dump_test "r_larch_32_elf64"
+ run_dump_test "ifunc-reloc"
}
if [check_pie_support] {
--
2.33.0
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