diff options
| author | Josh Stone <jistone@redhat.com> | 2015-06-05 14:28:03 -0700 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2015-06-08 18:34:21 +0100 |
| commit | 04d7e098f541769721d7511d56aea4b976fd29fd (patch) | |
| tree | 5804898ef893055a0ad5321f1ea8c80231842f80 /arch | |
| parent | addc8120a784181cc6410973948eee94ea16f2bd (diff) | |
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index d369ccff67e2..0eeb1b95c65a 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -611,11 +611,16 @@ ENDPROC(cpu_switch_to) */ ret_fast_syscall: disable_irq // disable interrupts - ldr x1, [tsk, #TI_FLAGS] + ldr x1, [tsk, #TI_FLAGS] // re-check for syscall tracing + and x2, x1, #_TIF_SYSCALL_WORK + cbnz x2, ret_fast_syscall_trace and x2, x1, #_TIF_WORK_MASK cbnz x2, fast_work_pending enable_step_tsk x1, x2 kernel_exit 0, ret = 1 +ret_fast_syscall_trace: + enable_irq // enable interrupts + b __sys_trace_return /* * Ok, we need to do extra processing, enter the slow path. |