[PATCH] LoongArch: Check PC-relative relocations for shared libraries
Lulu Cai
cailulu@loongson.cn
Sat Oct 5 09:57:13 GMT 2024
Building shared libraries should not be allowed for PC-relative
relocations against externally defined or undefined symbols.
Currently LoongArch has no corresponding checks and silently
generates wrong shared libraries.
However, PC-relative relocations are allowed when used as a function
call.
---
bfd/elfnn-loongarch.c | 21 +++++++++++++++
.../ld-loongarch-elf/bad_pcala_hi20.d | 5 ++++
.../ld-loongarch-elf/bad_pcala_hi20.s | 8 ++++++
.../ld-loongarch-elf/bad_pcrel20_s2.d | 5 ++++
.../ld-loongarch-elf/bad_pcrel20_s2.s | 8 ++++++
ld/testsuite/ld-loongarch-elf/data-plt.d | 5 ++++
.../ld-loongarch-elf/ld-loongarch-elf.exp | 27 +++----------------
7 files changed, 55 insertions(+), 24 deletions(-)
create mode 100644 ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.d
create mode 100644 ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.s
create mode 100644 ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.d
create mode 100644 ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.s
create mode 100644 ld/testsuite/ld-loongarch-elf/data-plt.d
diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index 63c6fdffd6b..6392a325465 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -1079,6 +1079,19 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
h->non_got_ref = 1;
break;
+ /* Since shared library global symbols interpose, any
+ PC-relative relocations against external symbols
+ (defined and undefined) should not be used to build
+ shared libraries. */
+ case R_LARCH_PCREL20_S2:
+ if (bfd_link_pic (info)
+ && (sec->flags & SEC_ALLOC) != 0
+ && (sec->flags & SEC_READONLY) != 0
+ && ! LARCH_REF_LOCAL (info, h))
+ return bad_static_reloc (abfd, rel, sec, r_type, h, NULL);
+
+ break;
+
/* For normal cmodel, pcalau12i + addi.d/w used to data.
For first version medium cmodel, pcalau12i + jirl are used to
function call, it need to creat PLT entry for STT_FUNC and
@@ -1096,6 +1109,14 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
h->pointer_equality_needed = 1;
}
+ /* PC-relative relocations are allowed when calling a function. */
+ if (h != NULL && !h->needs_plt
+ && bfd_link_pic (info)
+ && (sec->flags & SEC_ALLOC) != 0
+ && (sec->flags & SEC_READONLY) != 0
+ && ! LARCH_REF_LOCAL (info, h))
+ return bad_static_reloc (abfd, rel, sec, r_type, h, NULL);
+
break;
case R_LARCH_B16:
diff --git a/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.d b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.d
new file mode 100644
index 00000000000..481700b01ff
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.d
@@ -0,0 +1,5 @@
+#name: PC-relative relocation making shared
+#source: bad_pcala_hi20.s
+#target: [check_shared_lib_support]
+#ld: -shared --defsym global_a=0x10 --defsym global_b=0x20
+#error: .*: relocation R_LARCH_PCALA_HI20 against `global_b` can not be used when making a shared object; recompile with -fPIC
diff --git a/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.s b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.s
new file mode 100644
index 00000000000..d8189e45370
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/bad_pcala_hi20.s
@@ -0,0 +1,8 @@
+ .hidden global_a
+ .text
+ .align 2
+main:
+ # Symbols defined .hidden are bound local and
+ # the linker should differenciate them.
+ la.pcrel $a0, global_a
+ la.pcrel $a0, global_b
diff --git a/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.d b/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.d
new file mode 100644
index 00000000000..bd948a457a9
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.d
@@ -0,0 +1,5 @@
+#name: PC-relative relocation making shared
+#source: bad_pcrel20_s2.s
+#target: [check_shared_lib_support]
+#ld: -shared --defsym global_a=0x10 --defsym global_b=0x20
+#error: .*: relocation R_LARCH_PCREL20_S2 against `global_b` can not be used when making a shared object; recompile with -fPIC
diff --git a/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.s b/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.s
new file mode 100644
index 00000000000..39cedbd2743
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/bad_pcrel20_s2.s
@@ -0,0 +1,8 @@
+ .hidden global_a
+ .text
+ .align 2
+main:
+ # Symbols defined .hidden are bound local and
+ # the linker should differenciate them.
+ pcaddi $a0, %pcrel_20(global_a)
+ pcaddi $a0, %pcrel_20(global_b)
diff --git a/ld/testsuite/ld-loongarch-elf/data-plt.d b/ld/testsuite/ld-loongarch-elf/data-plt.d
new file mode 100644
index 00000000000..90e878d7b3f
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/data-plt.d
@@ -0,0 +1,5 @@
+#name: data plt
+#source: data-plt.s
+#target: [check_shared_lib_support]
+#ld: -shared
+#error: .*: relocation R_LARCH_PCALA_HI20 against `a` can not be used when making a shared object; recompile with -fPIC
diff --git a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
index 6bef97c260f..115c8c22f19 100644
--- a/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
+++ b/ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
@@ -73,30 +73,6 @@ if [istarget "loongarch64-*-*"] {
]
}
- # loongarch*-elf target do not support -shared option
- if [check_shared_lib_support] {
- run_ld_link_tests \
- [list \
- [list \
- "data plt" \
- "-shared" "" \
- "" \
- {data-plt.s} \
- {} \
- "data-plt.so" \
- ] \
- ]
-
- if [file exist "tmpdir/data-plt.so"] {
- set objdump_output [run_host_cmd "objdump" "-d tmpdir/data-plt.so"]
- if { [ regexp "<a@plt>" $objdump_output] } {
- fail "data plt"
- } {
- pass "data plt"
- }
- }
- }
-
run_ld_link_tests \
[list \
[list \
@@ -166,6 +142,9 @@ if [istarget "loongarch64-*-*"] {
run_dump_test "relr-got-shared"
run_dump_test "relr-text-shared"
run_dump_test "abssym_shared"
+ run_dump_test "data-plt"
+ run_dump_test "bad_pcrel20_s2"
+ run_dump_test "bad_pcala_hi20"
}
if [check_pie_support] {
--
2.34.1
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