Interestingly, the spinlock test works after I change tas() implementation FROM __sync_lock_test_and_set(lock, 1); TO __sync_val_compare_and_swap(lock, 0, 1);
## gcc (GCC) 8.3.1 20190311 (Red Hat 8.3.1-3) ==== __sync_lock_test_and_set(lock, 1) disassembly: ``` objdump -S a.out 000000000040073c <tas>: 40073c: d10043ff sub sp, sp, #0x10 400740: f90007e0 str x0, [sp, #8] 400744: f94007e0 ldr x0, [sp, #8] 400748: 52800021 mov w1, #0x1 // #1 40074c: 885f7c02 ldxr w2, [x0] 400750: 88037c01 stxr w3, w1, [x0] 400754: 35ffffc3 cbnz w3, 40074c <tas+0x10> 400758: d5033bbf dmb ish 40075c: 2a0203e0 mov w0, w2 400760: 910043ff add sp, sp, #0x10 400764: d65f03c0 ret ``` ==== __sync_val_compare_and_swap(lock, 0, 1); disassembly: ``` objdump -S a.out 000000000040073c <tas>: 40073c: d10043ff sub sp, sp, #0x10 400740: f90007e0 str x0, [sp, #8] 400744: f94007e0 ldr x0, [sp, #8] 400748: 52800021 mov w1, #0x1 // #1 40074c: 885f7c02 ldxr w2, [x0] 400750: 35000062 cbnz w2, 40075c <tas+0x20> 400754: 8803fc01 stlxr w3, w1, [x0] 400758: 35ffffa3 cbnz w3, 40074c <tas+0x10> 40075c: 7100005f cmp w2, #0x0 400760: d5033bbf dmb ish 400764: 2a0203e0 mov w0, w2 400768: 910043ff add sp, sp, #0x10 40076c: d65f03c0 ret ``` -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1908626 Title: Atomic test-and-set instruction does not work on qemu-user Status in QEMU: New Bug description: I try to compile and run PostgreSQL/Greenplum database inside docker container/qemu-aarch64-static: ``` host: CentOS7 x86_64 container: centos:centos7.9.2009 --platform linux/arm64/v8 qemu-user-static: https://github.com/multiarch/qemu-user-static/releases/ ``` However, GP/PG's spinlock always gets stuck and reports PANIC errors. It seems its spinlock has something wrong. ``` https://github.com/greenplum-db/gpdb/blob/master/src/include/storage/s_lock.h https://github.com/greenplum-db/gpdb/blob/master/src/backend/storage/lmgr/s_lock.c ``` So I extract its spinlock implementation into one test C source file (see attachment file), and get reprodcued: ``` $ gcc spinlock_qemu.c $ ./a.out C -- slock inited, lock value is: 0 parent 139642, child 139645 P -- slock lock before, lock value is: 0 P -- slock locked, lock value is: 1 P -- slock unlock after, lock value is: 0 C -- slock lock before, lock value is: 1 P -- slock lock before, lock value is: 1 C -- slock locked, lock value is: 1 C -- slock unlock after, lock value is: 0 C -- slock lock before, lock value is: 1 P -- slock locked, lock value is: 1 P -- slock unlock after, lock value is: 0 P -- slock lock before, lock value is: 1 C -- slock locked, lock value is: 1 C -- slock unlock after, lock value is: 0 P -- slock locked, lock value is: 1 C -- slock lock before, lock value is: 1 P -- slock unlock after, lock value is: 0 C -- slock locked, lock value is: 1 P -- slock lock before, lock value is: 1 C -- slock unlock after, lock value is: 0 P -- slock locked, lock value is: 1 C -- slock lock before, lock value is: 1 P -- slock unlock after, lock value is: 0 C -- slock locked, lock value is: 1 P -- slock lock before, lock value is: 1 C -- slock unlock after, lock value is: 0 P -- slock locked, lock value is: 1 C -- slock lock before, lock value is: 1 P -- slock unlock after, lock value is: 0 P -- slock lock before, lock value is: 1 spin timeout, lock value is 1 (pid 139642) spin timeout, lock value is 1 (pid 139645) spin timeout, lock value is 1 (pid 139645) spin timeout, lock value is 1 (pid 139642) spin timeout, lock value is 1 (pid 139645) spin timeout, lock value is 1 (pid 139642) ... ... ... ``` NOTE: this code always works on PHYSICAL ARM64 server. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1908626/+subscriptions
