arm64: fix missing syscall trace exit
authorJosh Stone <jistone@redhat.com>
Fri, 5 Jun 2015 21:28:03 +0000 (14:28 -0700)
committerCatalin Marinas <catalin.marinas@arm.com>
Mon, 8 Jun 2015 17:34:21 +0000 (18:34 +0100)
commit04d7e098f541769721d7511d56aea4b976fd29fd
tree5804898ef893055a0ad5321f1ea8c80231842f80
parentaddc8120a784181cc6410973948eee94ea16f2bd
arm64: fix missing syscall trace exit

If a syscall is entered without TIF_SYSCALL_TRACE set, then it goes on
the fast path.  It's then possible to have TIF_SYSCALL_TRACE added in
the middle of the syscall, but ret_fast_syscall doesn't check this flag
again.  This causes a ptrace syscall-exit-stop to be missed.

For instance, from a PTRACE_EVENT_FORK reported during do_fork, the
tracer might resume with PTRACE_SYSCALL, setting TIF_SYSCALL_TRACE.
Now the completion of the fork should have a syscall-exit-stop.

Russell King fixed this on arm by re-checking _TIF_SYSCALL_WORK in the
fast exit path.  Do the same on arm64.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Josh Stone <jistone@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch/arm64/kernel/entry.S