| Message ID | 1541508028-31865-9-git-send-email-leitao@debian.org (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | New TM Model | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
| snowpatch_ozlabs/checkpatch | warning | Test checkpatch on branch next |
On Tue, 2018-11-06 at 10:40 -0200, Breno Leitao wrote: > In the past, TIF_RESTORE_TM was being handled with the rest of the TIF > workers, > but, that was too early, and can cause some IRQ to be replayed in suspended > state (after recheckpoint). > > This patch moves TIF_RESTORE_TM handler to as late as possible, it also > forces the IRQ to be disabled, and it will continue to be until RFID, so, > no IRQ will be replayed at all. I.e, if trecheckpoint happens, it will RFID > to userspace. > > This makes TIF_RESTORE_TM a special case that should not be handled > similarly to the _TIF_USER_WORK_MASK. > > Since _TIF_RESTORE_TM is not part of _TIF_USER_WORK_MASK anymore, we > need to force system_call_exit to continue to leaves through > fast_exception_return, so, we add the flags together with > _TIF_USER_WORK_MASK at system_call_exist path. > > If this flag is set at system_call_exit, it means that recheckpoint > will be called, and doing it through fast_exception_return is the only > way to do so. > > Signed-off-by: Breno Leitao <leitao@debian.org> > --- > arch/powerpc/include/asm/thread_info.h | 2 +- > arch/powerpc/kernel/entry_64.S | 23 ++++++++++++++--------- > 2 files changed, 15 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/include/asm/thread_info.h > b/arch/powerpc/include/asm/thread_info.h > index 544cac0474cb..2835d60bc9ef 100644 > --- a/arch/powerpc/include/asm/thread_info.h > +++ b/arch/powerpc/include/asm/thread_info.h > @@ -139,7 +139,7 @@ void arch_setup_new_exec(void); > > #define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \ > _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ > - _TIF_RESTORE_TM | _TIF_PATCH_PENDING | \ > + _TIF_PATCH_PENDING | \ > _TIF_FSCHECK) > #define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR) > > diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S > index 17484ebda66c..a86619edf29d 100644 > --- a/arch/powerpc/kernel/entry_64.S > +++ b/arch/powerpc/kernel/entry_64.S > @@ -255,7 +255,7 @@ system_call_exit: > > ld r9,TI_FLAGS(r12) > li r11,-MAX_ERRNO > - andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MAS > K|_TIF_PERSYSCALL_MASK) > + andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK| > _TIF_PERSYSCALL_MASK |_TIF_RESTORE_TM) > bne- .Lsyscall_exit_work > > andi. r0,r8,MSR_FP > @@ -784,14 +784,6 @@ _GLOBAL(ret_from_except_lite) > SCHEDULE_USER > b ret_from_except_lite > 2: > -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM > - andi. r0,r4,_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM > - bne 3f /* only restore TM if nothing else to do */ > - addi r3,r1,STACK_FRAME_OVERHEAD > - bl restore_tm_state > - b restore > -3: > -#endif > bl save_nvgprs > /* > * Use a non volatile GPR to save and restore our thread_info flags > @@ -938,6 +930,19 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) > */ > .globl fast_exception_return > fast_exception_return: > + > +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM > + CURRENT_THREAD_INFO(r4, r1) > + ld r4,TI_FLAGS(r4) > + andi. r0,r4,_TIF_RESTORE_TM > + beq 22f > + ld r4,_MSR(r1) /* TODO: MSR[!PR] shouldn't be here */ > + andi. r0,r4,MSR_PR > + beq 22f /* Skip if Kernel thread */ > + addi r3,r1,STACK_FRAME_OVERHEAD > + bl restore_tm_state Calling out to C here is a bit concerning this late. The main thing you are calling out to is asm anyway (with a small C wrapper). We might want to adapt the asm this case, rather than the old model of getting it called from __switch_to(). We shouldn't need to call tm_reclaim/tm_recheckpoint from C anymore (especially if we use BUG_ON() rather than WARN_ON() in the cases already mentioned.). Same for patch 1. > +22: > +#endif > ld r3,_MSR(r1) > ld r4,_CTR(r1) > ld r0,_LINK(r1)
diff --git a/arch/powerpc/include/asm/thread_info.h b/arch/powerpc/include/asm/thread_info.h index 544cac0474cb..2835d60bc9ef 100644 --- a/arch/powerpc/include/asm/thread_info.h +++ b/arch/powerpc/include/asm/thread_info.h @@ -139,7 +139,7 @@ void arch_setup_new_exec(void); #define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \ _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ - _TIF_RESTORE_TM | _TIF_PATCH_PENDING | \ + _TIF_PATCH_PENDING | \ _TIF_FSCHECK) #define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 17484ebda66c..a86619edf29d 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -255,7 +255,7 @@ system_call_exit: ld r9,TI_FLAGS(r12) li r11,-MAX_ERRNO - andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) + andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK |_TIF_RESTORE_TM) bne- .Lsyscall_exit_work andi. r0,r8,MSR_FP @@ -784,14 +784,6 @@ _GLOBAL(ret_from_except_lite) SCHEDULE_USER b ret_from_except_lite 2: -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM - andi. r0,r4,_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM - bne 3f /* only restore TM if nothing else to do */ - addi r3,r1,STACK_FRAME_OVERHEAD - bl restore_tm_state - b restore -3: -#endif bl save_nvgprs /* * Use a non volatile GPR to save and restore our thread_info flags @@ -938,6 +930,19 @@ ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) */ .globl fast_exception_return fast_exception_return: + +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + CURRENT_THREAD_INFO(r4, r1) + ld r4,TI_FLAGS(r4) + andi. r0,r4,_TIF_RESTORE_TM + beq 22f + ld r4,_MSR(r1) /* TODO: MSR[!PR] shouldn't be here */ + andi. r0,r4,MSR_PR + beq 22f /* Skip if Kernel thread */ + addi r3,r1,STACK_FRAME_OVERHEAD + bl restore_tm_state +22: +#endif ld r3,_MSR(r1) ld r4,_CTR(r1) ld r0,_LINK(r1)
In the past, TIF_RESTORE_TM was being handled with the rest of the TIF workers, but, that was too early, and can cause some IRQ to be replayed in suspended state (after recheckpoint). This patch moves TIF_RESTORE_TM handler to as late as possible, it also forces the IRQ to be disabled, and it will continue to be until RFID, so, no IRQ will be replayed at all. I.e, if trecheckpoint happens, it will RFID to userspace. This makes TIF_RESTORE_TM a special case that should not be handled similarly to the _TIF_USER_WORK_MASK. Since _TIF_RESTORE_TM is not part of _TIF_USER_WORK_MASK anymore, we need to force system_call_exit to continue to leaves through fast_exception_return, so, we add the flags together with _TIF_USER_WORK_MASK at system_call_exist path. If this flag is set at system_call_exit, it means that recheckpoint will be called, and doing it through fast_exception_return is the only way to do so. Signed-off-by: Breno Leitao <leitao@debian.org> --- arch/powerpc/include/asm/thread_info.h | 2 +- arch/powerpc/kernel/entry_64.S | 23 ++++++++++++++--------- 2 files changed, 15 insertions(+), 10 deletions(-)