From: Boqun Feng <boqun.feng@xxxxxxxxx> Syscalls are not allowed inside restartable sequences, so add a call to rseq_syscall() at the very beginning of system call exiting path for CONFIG_DEBUG_RSEQ=y kernel. This could help us to detect whether there is a syscall issued inside restartable sequences. [ Tested on 64-bit powerpc kernel by Mathieu Desnoyers. Still needs to be tested on 32-bit powerpc kernel. ] Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> CC: Paul Mackerras <paulus@xxxxxxxxx> CC: Michael Ellerman <mpe@xxxxxxxxxxxxxx> CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CC: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> CC: linuxppc-dev@xxxxxxxxxxxxxxxx --- arch/powerpc/kernel/entry_32.S | 7 +++++++ arch/powerpc/kernel/entry_64.S | 8 ++++++++ 2 files changed, 15 insertions(+) diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index eb8d01bae8c6..973577f2141c 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -365,6 +365,13 @@ syscall_dotrace_cont: blrl /* Call handler */ .globl ret_from_syscall ret_from_syscall: +#ifdef CONFIG_DEBUG_RSEQ + /* Check whether the syscall is issued inside a restartable sequence */ + stw r3,GPR3(r1) + addi r3,r1,STACK_FRAME_OVERHEAD + bl rseq_syscall + lwz r3,GPR3(r1) +#endif mr r6,r3 CURRENT_THREAD_INFO(r12, r1) /* disable interrupts so current_thread_info()->flags can't change */ diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 51695608c68b..1c374387656a 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -184,6 +184,14 @@ system_call: /* label this so stack traces look sane */ .Lsyscall_exit: std r3,RESULT(r1) + +#ifdef CONFIG_DEBUG_RSEQ + /* Check whether the syscall is issued inside a restartable sequence */ + addi r3,r1,STACK_FRAME_OVERHEAD + bl rseq_syscall + ld r3,RESULT(r1) +#endif + CURRENT_THREAD_INFO(r12, r1) ld r8,_MSR(r1) -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
