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[BFD][AARCH64]Disallow R_AARCH64_ABS32(LP64) & R_AARCH64_ABS16 in const section of shared object.

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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 meaningless 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 constant 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.
This commit is contained in:
Renlin Li 2017-12-13 12:11:25 +00:00
parent 9664701462
commit 79e7419204
9 changed files with 64 additions and 3 deletions
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6
bfd/ChangeLog
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@ -1,3 +1,9 @@
2017-12-13 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.
2017-12-11 Sangamesh Mallayya <sangamesh.swamy@in.ibm.com>
* bfd.c (bfd_get_sign_extend_vma): Correct typo.

21
bfd/elfnn-aarch64.c
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@ -7070,6 +7070,27 @@ 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
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
/* xgettext:c-format */
(_("%B: relocation %s against `%s' can not be used when making "
"a shared object"),
abfd, elfNN_aarch64_howto_table[howto_index].name,
(h) ? h->root.root.string : "a local symbol");
bfd_set_error (bfd_error_bad_value);
return FALSE;
}
else
break;
case BFD_RELOC_AARCH64_MOVW_G0_NC:
case BFD_RELOC_AARCH64_MOVW_G1_NC:
case BFD_RELOC_AARCH64_MOVW_G2_NC:

10
ld/ChangeLog
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@ -1,3 +1,13 @@
2017-12-13 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.
2017-12-07 Alan Modra <amodra@gmail.com>
PR 22465

2
ld/testsuite/ld-aarch64/aarch64-elf.exp
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@ -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_lp64 "emit-relocs-258-dyn-bad"
run_dump_test_lp64 "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

4
ld/testsuite/ld-aarch64/emit-relocs-258-dyn-bad.d Normal file
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@ -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

6
ld/testsuite/ld-aarch64/emit-relocs-258.s Normal file
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@ -0,0 +1,6 @@
.text
ldr x0, .L1
.L1:
.word dummy

4
ld/testsuite/ld-aarch64/emit-relocs-259-dyn-bad.d Normal file
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@ -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

6
ld/testsuite/ld-aarch64/emit-relocs-259.s Normal file
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@ -0,0 +1,6 @@
.text
ldr x0, .L1
.L1:
.hword dummy

8
ld/testsuite/ld-aarch64/gc-relocs-257.s
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@ -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