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authorMark Rutland <mark.rutland@arm.com>2018-04-03 11:22:51 +0100
committerWill Deacon <will.deacon@arm.com>2018-04-24 19:07:36 +0100
commit9478f1927e6ef9ef5e1ad761af1c98aa8e40b7f5 (patch)
tree585789158e71ac5acce4a4f7146b803a26813e8b /arch
parented231ae384fdfcb546b63b2fe7add65029e3a94c (diff)
downloadlinux-9478f1927e6ef9ef5e1ad761af1c98aa8e40b7f5.tar.bz2
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: 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>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/traps.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 1cb2749a72bf..8bbdc17e49df 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -277,7 +277,8 @@ 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.
*/
- user_fastforward_single_step(current);
+ if (user_mode(regs))
+ user_fastforward_single_step(current);
}
static LIST_HEAD(undef_hook);