Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> writes: > ----- On May 23, 2018, at 4:14 PM, Mathieu Desnoyers mathieu.desnoyers@xxxxxxxxxxxx wrote: ... >> >> Hi Boqun, >> >> I tried your patch in a ppc64 le environment, and it does not survive boot >> with CONFIG_DEBUG_RSEQ=y. init gets killed right away. Sorry this code is super gross and hard to deal with. > The following fixup gets ppc64 to work: > > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -208,6 +208,7 @@ system_call_exit: > /* Check whether the syscall is issued inside a restartable sequence */ > addi r3,r1,STACK_FRAME_OVERHEAD > bl rseq_syscall > + ld r3,RESULT(r1) > #endif > /* > * Disable interrupts so current_thread_info()->flags can't change, I don't think that's safe. If you look above that, we have r3, r8 and r12 all live: .Lsyscall_exit: std r3,RESULT(r1) CURRENT_THREAD_INFO(r12, r1) ld r8,_MSR(r1) #ifdef CONFIG_PPC_BOOK3S /* No MSR:RI on BookE */ andi. r10,r8,MSR_RI beq- .Lunrecov_restore #endif They're all volatile across function calls: http://openpowerfoundation.org/wp-content/uploads/resources/leabi/content/dbdoclet.50655240_68174.html The system_call_exit symbol is actually there for kprobes and cosmetic purposes. The actual syscall return flow starts at .Lsyscall_exit. So I think this would work: diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index db4df061c33a..e19f377a25e0 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) I'll try and get this series into my test setup at some point, been a bit busy lately :) cheers -- 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
