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Subject[PATCH 2/4] MIPS: Add syscall detection for restartable sequences
Date
Syscalls are not allowed inside restartable sequences, so add a call to
rseq_syscall() at the very beginning of the system call exit path when
CONFIG_DEBUG_RSEQ=y. This will help us to detect whether there is a
syscall issued erroneously inside a restartable sequence.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
---

arch/mips/kernel/entry.S | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/arch/mips/kernel/entry.S b/arch/mips/kernel/entry.S
index 38a302919e6b..d7de8adcfcc8 100644
--- a/arch/mips/kernel/entry.S
+++ b/arch/mips/kernel/entry.S
@@ -79,6 +79,10 @@ FEXPORT(ret_from_fork)
jal schedule_tail # a0 = struct task_struct *prev

FEXPORT(syscall_exit)
+#ifdef CONFIG_DEBUG_RSEQ
+ move a0, sp
+ jal rseq_syscall
+#endif
local_irq_disable # make sure need_resched and
# signals dont change between
# sampling and return
@@ -141,6 +145,10 @@ work_notifysig: # deal with pending signals and
j resume_userspace_check

FEXPORT(syscall_exit_partial)
+#ifdef CONFIG_DEBUG_RSEQ
+ move a0, sp
+ jal rseq_syscall
+#endif
local_irq_disable # make sure need_resched doesn't
# change between and return
LONG_L a2, TI_FLAGS($28) # current->work
--
2.17.1
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