https://sourceware.org/bugzilla/show_bug.cgi?id=32572
Bug ID: 32572
Summary: -z force-bti + -Ttext-segment produce wrong PLT
entries on aarch64
Product: binutils
Version: 2.44 (HEAD)
Status: NEW
Severity: normal
Priority: P2
Component: ld
Assignee: unassigned at sourceware dot org
Reporter: aurelien at aurel32 dot net
Target Milestone: ---
Host: aarch64-unknown-linux-gnu
Target: aarch64-unknown-linux-gnu
Build: aarch64-unknown-linux-gnu
The future glibc 2.41 added two new tests, elf/tst-pie-address and
elf/tst-pie-address-static, that fail when enabling PAC/BTI on aarch64. Further
investigation by Adhemerval Zanella Netto [2] shows that ld generate wrong plt
entries when -z force-bti and -Ttext-segment options are used together:
* default options
00000000000012e0 <memcpy@plt>:
12e0: f00000f0 adrp x16, 20000 <memcpy@GLIBC_2.17>
12e4: f9400211 ldr x17, [x16]
12e8: 91000210 add x16, x16, #0x0
12ec: d61f0220 br x17
* with -Ttext-segment=0x0000000000400000
00000000004012e0 <memcpy@plt>:
4012e0: f00000f0 adrp x16, 420000 <memcpy@GLIBC_2.17>
4012e4: f9400211 ldr x17, [x16]
4012e8: 91000210 add x16, x16, #0x0
4012ec: d61f0220 br x17
* with -z force-bti
0000000000001370 <memcpy@plt>:
1370: f00000f0 adrp x16, 20000 <memcpy@GLIBC_2.17>
1374: f9400211 ldr x17, [x16]
1378: 91000210 add x16, x16, #0x0
137c: d61f0220 br x17
* with -z force-bti + -Ttext-segment=0x0000000000400000
0000000000401370 <memcpy@plt>:
401370: 90000010 adrp x16, 401000 <_init-0x328>
401374: f90000f1 str x17, [x7]
401378: 91000210 add x16, x16, #0x0
40137c: d6000220 .inst 0xd6000220 ; undefined
401380: 90000010 adrp x16, 401000 <_init-0x328>
401384: f90000f1 str x17, [x7]
[1]
https://sourceware.org/git/?p=glibc.git;a=commit;h=e7b553272196e6175b8a15f807cb59217ba2843a
[2] https://sourceware.org/pipermail/libc-alpha/2025-January/164046.html
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