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  • AKASHI Takahiro's avatar
    arm64: ptrace: allow tracer to skip a system call · 1014c81d
    AKASHI Takahiro authored
    
    
    If tracer modifies a syscall number to -1, this traced system call should
    be skipped with a return value specified in x0.
    This patch implements this semantics.
    
    Please note:
    * syscall entry tracing and syscall exit tracing (ftrace tracepoint and
      audit) are always executed, if enabled, even when skipping a system call
      (that is, -1).
      In this way, we can avoid a potential bug where audit_syscall_entry()
      might be called without audit_syscall_exit() at the previous system call
      being called, that would cause OOPs in audit_syscall_entry().
    
    Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
    [will: fixed up conflict with blr rework]
    Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
    1014c81d