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[BFD][AARCH64]Disallow R_AARCH64_ABS32(LP64) & R_AARCH64_ABS16 in const section of shared object
- From: Renlin Li <renlin dot li at foss dot arm dot com>
- To: "binutils at sourceware dot org" <binutils at sourceware dot org>, Nicholas Clifton <nickc at redhat dot com>, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>
- Date: Wed, 18 Oct 2017 11:40:43 +0100
- Subject: [BFD][AARCH64]Disallow R_AARCH64_ABS32(LP64) & R_AARCH64_ABS16 in const section of shared object
- Authentication-results: sourceware.org; auth=none
Hi all,
R_AARCH64_ABS64, R_AARCH64_ABS32 and R_AARCH64_ABS16 are data relocations
supported in AArch64 elf ABI.
R_AARCH64_ABS64 under LP64 is allowed in shared object and a dynamic relocation entry
will be generated. This allows the dynamic linker to do further symbol resolution.
R_AARCH64_ABS32 likewise is allowed in shared object, however under ILP32 abi.
The original behavior for R_AARCH64_ABS32 under LP64 is that, it's allowed
in shared object and silently resolved at static linking time.
No dynamic relocation entry is generate for it.
R_AARCH64_ABS16 is allowed in shared object under both L64 and ILP32.
It's resolved at static linking time as well.
Under LP64, the address should be 64-bit. R_AARCH64_ABS32 relocation indicates
an address that is only sized 32 bits which is not correct in LP64 shared object.
It's useful to error out.
I have checked glibc dynamic linker code, R_AARCH64_ABS16 is not supported at all. So
R_AARCH64_ABS16 should be reject in shared object completely.
In this patch, R_AARCH64_ABS32 is rejected under LP64 in read-only section of shared object.
R_AARCH64_ABS16 is rejected in constant section of shared object in both ABI.
This will sometimes provide useful information for buggy code.
By the way, glibc aarch64 elf_machine_load_address is using R_AARCH64_ABS32 to hold an
address even in LP64. I had a discussion here sometime ago. The change here will break the
glibc build. This patch will not be committed until glibc has been fixed.
https://sourceware.org/ml/libc-alpha/2017-10/msg00816.html
testcases are also added. Binutils regression checked OK.
Linux kernel linked OK with new binutils. OK for trunk?
Regards,
Renlin Li
ld/ChangeLog:
2017-10-18 Renlin Li <renlin.li@arm.com>
* testsuite/ld-aarch64/aarch64-elf.exp: Run new test cases.
* testsuite/ld-aarch64/emit-relocs-258-dyn-bad.d: New.
* testsuite/ld-aarch64/emit-relocs-258.s: New.
* testsuite/ld-aarch64/emit-relocs-259-dyn-bad.d: New.
* testsuite/ld-aarch64/emit-relocs-259.s: New.
* testsuite/ld-aarch64/gc-relocs-257.s: Put R_AARCH64_ABS32,
R_AARCH64_ABS16 data into data section.
bfd/ChangeLog:
2017-10-18 Renlin Li <renlin.li@arm.com>
* elfnn-aarch64.c (elfNN_aarch64_check_relocs): Disallow
BFD_RELOC_AARCH64_16 in shared object const section. Disallow
BFD_RELOC_AARCH64_32 in shared object const section under LP64.
diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 23c881c..bdc7c80 100644
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -7058,11 +7058,17 @@ elfNN_aarch64_check_relocs (bfd *abfd, struct bfd_link_info *info,
switch (bfd_r_type)
{
+ case BFD_RELOC_AARCH64_16:
+#if ARCH_SIZE == 64
+ case BFD_RELOC_AARCH64_32:
+#endif
case BFD_RELOC_AARCH64_MOVW_G0_NC:
case BFD_RELOC_AARCH64_MOVW_G1_NC:
case BFD_RELOC_AARCH64_MOVW_G2_NC:
case BFD_RELOC_AARCH64_MOVW_G3:
- if (bfd_link_pic (info))
+ if (bfd_link_pic (info)
+ && (sec->flags & SEC_ALLOC) != 0
+ && (sec->flags & SEC_READONLY) != 0)
{
int howto_index = bfd_r_type - BFD_RELOC_AARCH64_RELOC_START;
_bfd_error_handler
diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index b9c9885..fbc4f86 100644
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -103,6 +103,8 @@ run_dump_test_lp64 "emit-relocs-257"
run_dump_test_lp64 "emit-relocs-257-be"
# 258 is tested in 257
# 259 is tested in 257
+run_dump_test "emit-relocs-258-dyn-bad"
+run_dump_test "emit-relocs-259-dyn-bad"
run_dump_test_lp64 "emit-relocs-260"
run_dump_test_lp64 "emit-relocs-260-be"
# 261 is tested by 260
diff --git a/ld/testsuite/ld-aarch64/emit-relocs-258-dyn-bad.d b/ld/testsuite/ld-aarch64/emit-relocs-258-dyn-bad.d
new file mode 100644
index 0000000..cbd4577
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/emit-relocs-258-dyn-bad.d
@@ -0,0 +1,4 @@
+#name: LP64 R_AARCH64_ABS32 shared library test
+#source: emit-relocs-258.s
+#ld: -shared
+#error: .*: relocation R_AARCH64_ABS32 against `dummy' can not be used when making a shared object; recompile with -fPIC
diff --git a/ld/testsuite/ld-aarch64/emit-relocs-258.s b/ld/testsuite/ld-aarch64/emit-relocs-258.s
new file mode 100644
index 0000000..f724776
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/emit-relocs-258.s
@@ -0,0 +1,6 @@
+.text
+
+ ldr x0, .L1
+
+.L1:
+ .word dummy
diff --git a/ld/testsuite/ld-aarch64/emit-relocs-259-dyn-bad.d b/ld/testsuite/ld-aarch64/emit-relocs-259-dyn-bad.d
new file mode 100644
index 0000000..6e111c6e
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/emit-relocs-259-dyn-bad.d
@@ -0,0 +1,4 @@
+#name: R_AARCH64_ABS16 shared library test
+#source: emit-relocs-259.s
+#ld: -shared
+#error: .*: relocation R_AARCH64_ABS16 against `dummy' can not be used when making a shared object; recompile with -fPIC
diff --git a/ld/testsuite/ld-aarch64/emit-relocs-259.s b/ld/testsuite/ld-aarch64/emit-relocs-259.s
new file mode 100644
index 0000000..7e1ba3c
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/emit-relocs-259.s
@@ -0,0 +1,6 @@
+.text
+
+ ldr x0, .L1
+
+.L1:
+ .hword dummy
diff --git a/ld/testsuite/ld-aarch64/gc-relocs-257.s b/ld/testsuite/ld-aarch64/gc-relocs-257.s
index dcc9db1..f57f9c6 100644
--- a/ld/testsuite/ld-aarch64/gc-relocs-257.s
+++ b/ld/testsuite/ld-aarch64/gc-relocs-257.s
@@ -1,8 +1,10 @@
.text
- .word tempy
+ and x0, x0, x0
+ and x0, x0, #0x1
.xword tempy2
+
+ .data
+ .word tempy
.hword tempy3
.hword tempy3+8
- and x0, x0, x0
- and x0, x0, #0x1