[RFC PATCH 02/11] powerpc/tm: Reclaim on unavailable exception
From: Breno Leitao <leitao@debian.org>
Date: 2018-09-12 19:40:36
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
If there is a FP/VEC/Altivec touch inside a transaction and the facility is
disabled, then a facility unavailable exception is raised and ends up
calling {fp,vec,vsx}_unavailable_tm, which was reclaiming and recheckpointing.
This is not required anymore, since the checkpointed state was reclaimed in
the trap entrace itself, and it will be recheckpointed by restore_tm_state
later.
With this new patchset, we only reclaim at exception entrance (except at
syscall level if the transaction is suspended), and always recheckpoint on
restore_tm_state.
Adding a WARN_ON() warning if we hit the _unavailable_tm() in suspended
mode, i.e, the reclaim was not executed somehow in the trap entrance.
Signed-off-by: Breno Leitao <leitao@debian.org>
---
arch/powerpc/kernel/exceptions-64s.S | 3 +++
arch/powerpc/kernel/traps.c | 16 ++++------------
2 files changed, 7 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 78aba71a4b2d..4108f3944bdd 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S@@ -874,6 +874,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM) #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 2: /* User process was in a transaction */ bl save_nvgprs + TM_KERNEL_ENTRY(TM_CAUSE_FAC_UNAV) RECONCILE_IRQ_STATE(r10, r11) addi r3,r1,STACK_FRAME_OVERHEAD bl fp_unavailable_tm
@@ -1216,6 +1217,7 @@ BEGIN_FTR_SECTION #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 2: /* User process was in a transaction */ bl save_nvgprs + TM_KERNEL_ENTRY(TM_CAUSE_FAC_UNAV) RECONCILE_IRQ_STATE(r10, r11) addi r3,r1,STACK_FRAME_OVERHEAD bl altivec_unavailable_tm
@@ -1252,6 +1254,7 @@ BEGIN_FTR_SECTION #ifdef CONFIG_PPC_TRANSACTIONAL_MEM 2: /* User process was in a transaction */ bl save_nvgprs + TM_KERNEL_ENTRY(TM_CAUSE_FAC_UNAV) RECONCILE_IRQ_STATE(r10, r11) addi r3,r1,STACK_FRAME_OVERHEAD bl vsx_unavailable_tm
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index c85adb858271..b973fdb72826 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c@@ -1749,19 +1749,12 @@ void fp_unavailable_tm(struct pt_regs *regs) * transaction, and probably retry but now with FP enabled. So the * checkpointed FP registers need to be loaded. */ - tm_reclaim_current(TM_CAUSE_FAC_UNAV); + WARN_ON(MSR_TM_SUSPENDED(mfmsr())); /* Reclaim didn't save out any FPRs to transact_fprs. */ /* Enable FP for the task: */ current->thread.load_fp = 1; - /* This loads and recheckpoints the FP registers from - * thread.fpr[]. They will remain in registers after the - * checkpoint so we don't need to reload them after. - * If VMX is in use, the VRs now hold checkpointed values, - * so we don't want to load the VRs from the thread_struct. - */ - tm_recheckpoint(¤t->thread); } void altivec_unavailable_tm(struct pt_regs *regs)
@@ -1773,10 +1766,10 @@ void altivec_unavailable_tm(struct pt_regs *regs) TM_DEBUG("Vector Unavailable trap whilst transactional at 0x%lx," "MSR=%lx\n", regs->nip, regs->msr); - tm_reclaim_current(TM_CAUSE_FAC_UNAV); + WARN_ON(MSR_TM_SUSPENDED(mfmsr())); current->thread.load_vec = 1; - tm_recheckpoint(¤t->thread); current->thread.used_vr = 1; + } void vsx_unavailable_tm(struct pt_regs *regs)
@@ -1795,12 +1788,11 @@ void vsx_unavailable_tm(struct pt_regs *regs) current->thread.used_vsr = 1; /* This reclaims FP and/or VR regs if they're already enabled */ - tm_reclaim_current(TM_CAUSE_FAC_UNAV); + WARN_ON(MSR_TM_SUSPENDED(mfmsr())); current->thread.load_vec = 1; current->thread.load_fp = 1; - tm_recheckpoint(¤t->thread); } #endif /* CONFIG_PPC_TRANSACTIONAL_MEM */
--
2.19.0