Masami Hiramatsu b3980e4852 arm64: kprobes: Recover pstate.D in single-step exception handler ... kprobes manipulates the interrupted PSTATE for single step, and doesn't restore it. Thus, if we put a kprobe where the pstate.D (debug) masked, the mask will be cleared after the kprobe hits. Moreover, in the most complicated case, this can lead a kernel crash with below message when a nested kprobe hits. [ 152.118921] Unexpected kernel single-step exception at EL1 When the 1st kprobe hits, do_debug_exception() will be called. At this point, debug exception (= pstate.D) must be masked (=1). But if another kprobes hits before single-step of the first kprobe (e.g. inside user pre_handler), it unmask the debug exception (pstate.D = 0) and return. Then, when the 1st kprobe setting up single-step, it saves current DAIF, mask DAIF, enable single-step, and restore DAIF. However, since "D" flag in DAIF is cleared by the 2nd kprobe, the single-step exception happens soon after restoring DAIF. This has been introduced by commit 7419333fa1 ("arm64: kprobe: Always clear pstate.D in breakpoint exception handler") To solve this issue, this stores all DAIF bits and restore it after single stepping. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Fixes: 7419333fa1 ("arm64: kprobe: Always clear pstate.D in breakpoint exception handler") Reviewed-by: James Morse <james.morse@arm.com> Tested-by: James Morse <james.morse@arm.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Will Deacon <will@kernel.org>		2019-08-02 11:55:50 +01:00
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decode-insn.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174	2019-05-30 11:26:41 -07:00
decode-insn.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174	2019-05-30 11:26:41 -07:00
kprobes_trampoline.S	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
kprobes.c	arm64: kprobes: Recover pstate.D in single-step exception handler	2019-08-02 11:55:50 +01:00
Makefile	License cleanup: add SPDX GPL-2.0 license identifier to files with no license	2017-11-02 11:10:55 +01:00
simulate-insn.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174	2019-05-30 11:26:41 -07:00
simulate-insn.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174	2019-05-30 11:26:41 -07:00
uprobes.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500	2019-06-19 17:09:55 +02:00