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7a76f21867
Originally, nptl/descr.h included <sys/rseq.h>, but we removed that in commit2c6b4b272e("nptl: Unconditionally use a 32-byte rseq area"). After that, it was not ensured that the RSEQ_SIG macro was defined during sched_getcpu.c compilation that provided a definition. This commit always checks the rseq area for CPU number information before using the other approaches. This adds an unnecessary (but well-predictable) branch on architectures which do not define RSEQ_SIG, but its cost is small compared to the system call. Most architectures that have vDSO acceleration for getcpu also have rseq support. Fixes:2c6b4b272eFixes:1d350aa060Reviewed-by: Arjun Shankar <arjun@redhat.com>