Commit 9478f192 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon

arm64: only advance singlestep for user instruction traps

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: default avatarMark 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: default avatarWill Deacon <will.deacon@arm.com>
parent ed231ae3
......@@ -277,6 +277,7 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
* If we were single stepping, we want to get the step exception after
* we return from the trap.
*/
if (user_mode(regs))
user_fastforward_single_step(current);
}
......
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