Mark Rutland 3e7acc963f arm64: only advance singlestep for user instruction traps
commit 9478f1927e6ef9ef5e1ad761af1c98aa8e40b7f5 upstream.

Our arm64_skip_faulting_instruction() helper advances the userspace
singlestep state machine, but this is also called by the kernel BRK
handler, as used for WARN*().

Thus, if we happen to hit a WARN*() while the user singlestep state
machine is in the active-no-pending state, we'll advance to the
active-pending state without having executed a user instruction, and
will take a step exception earlier than expected when we return to
userspace.

Let's fix this by only advancing the state machine when skipping a user
instruction.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-08 07:20:45 +02:00
..
2019-02-20 10:20:53 +01:00
2018-02-28 10:19:44 +01:00
2019-03-23 14:35:21 +01:00
2018-11-13 11:14:50 -08:00
2019-04-17 08:37:54 +02:00