From 702f0980522239bc7fd1360b24f722a90b6b4418 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 26 Feb 2020 03:35:38 +1000 Subject: [PATCH] powerpc/64s/exception: Remove lite interrupt return Regular interrupt return restores NVGPRS whereas lite returns do not. This is clumsy: most interrupts can return without restoring NVGPRS in most of the time, but there are special cases that require it (when registers have been modified by the kernel). So change interrupt return to not restore NVGPRS, and have interrupt handlers restore them explicitly in the cases that requires it. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200225173541.1549955-30-npiggin@gmail.com --- arch/powerpc/kernel/entry_64.S | 6 ------ arch/powerpc/kernel/exceptions-64s.S | 24 ++++++++++++++---------- 2 files changed, 14 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 5d782ac..95905ed 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -479,12 +479,6 @@ _ASM_NOKPROBE_SYMBOL(fast_interrupt_return) .globl interrupt_return interrupt_return: _ASM_NOKPROBE_SYMBOL(interrupt_return) - REST_NVGPRS(r1) - - .balign IFETCH_ALIGN_BYTES - .globl interrupt_return_lite -interrupt_return_lite: -_ASM_NOKPROBE_SYMBOL(interrupt_return_lite) ld r4,_MSR(r1) andi. r0,r4,MSR_PR beq .Lkernel_interrupt_return diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 1124403..18bbce1 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1529,7 +1529,7 @@ EXC_COMMON_BEGIN(hardware_interrupt_common) RUNLATCH_ON addi r3,r1,STACK_FRAME_OVERHEAD bl do_IRQ - b interrupt_return_lite + b interrupt_return GEN_KVM hardware_interrupt @@ -1557,6 +1557,7 @@ EXC_COMMON_BEGIN(alignment_common) GEN_COMMON alignment addi r3,r1,STACK_FRAME_OVERHEAD bl alignment_exception + REST_NVGPRS(r1) /* instruction emulation may change GPRs */ b interrupt_return GEN_KVM alignment @@ -1620,6 +1621,7 @@ EXC_COMMON_BEGIN(program_check_common) 3: addi r3,r1,STACK_FRAME_OVERHEAD bl program_check_exception + REST_NVGPRS(r1) /* instruction emulation may change GPRs */ b interrupt_return GEN_KVM program_check @@ -1716,7 +1718,7 @@ EXC_COMMON_BEGIN(decrementer_common) RUNLATCH_ON addi r3,r1,STACK_FRAME_OVERHEAD bl timer_interrupt - b interrupt_return_lite + b interrupt_return GEN_KVM decrementer @@ -1807,7 +1809,7 @@ EXC_COMMON_BEGIN(doorbell_super_common) #else bl unknown_exception #endif - b interrupt_return_lite + b interrupt_return GEN_KVM doorbell_super @@ -2076,6 +2078,7 @@ EXC_COMMON_BEGIN(emulation_assist_common) GEN_COMMON emulation_assist addi r3,r1,STACK_FRAME_OVERHEAD bl emulation_assist_interrupt + REST_NVGPRS(r1) /* instruction emulation may change GPRs */ b interrupt_return GEN_KVM emulation_assist @@ -2194,7 +2197,7 @@ EXC_COMMON_BEGIN(h_doorbell_common) #else bl unknown_exception #endif - b interrupt_return_lite + b interrupt_return GEN_KVM h_doorbell @@ -2224,7 +2227,7 @@ EXC_COMMON_BEGIN(h_virt_irq_common) RUNLATCH_ON addi r3,r1,STACK_FRAME_OVERHEAD bl do_IRQ - b interrupt_return_lite + b interrupt_return GEN_KVM h_virt_irq @@ -2271,7 +2274,7 @@ EXC_COMMON_BEGIN(performance_monitor_common) RUNLATCH_ON addi r3,r1,STACK_FRAME_OVERHEAD bl performance_monitor_exception - b interrupt_return_lite + b interrupt_return GEN_KVM performance_monitor @@ -2668,6 +2671,7 @@ EXC_COMMON_BEGIN(altivec_assist_common) addi r3,r1,STACK_FRAME_OVERHEAD #ifdef CONFIG_ALTIVEC bl altivec_assist_exception + REST_NVGPRS(r1) /* instruction emulation may change GPRs */ #else bl unknown_exception #endif @@ -3057,7 +3061,7 @@ do_hash_page: cmpdi r3,0 /* see if __hash_page succeeded */ /* Success */ - beq interrupt_return_lite /* Return from exception on success */ + beq interrupt_return /* Return from exception on success */ /* Error */ blt- 13f @@ -3074,7 +3078,7 @@ handle_page_fault: addi r3,r1,STACK_FRAME_OVERHEAD bl do_page_fault cmpdi r3,0 - beq+ interrupt_return_lite + beq+ interrupt_return mr r5,r3 addi r3,r1,STACK_FRAME_OVERHEAD ld r4,_DAR(r1) @@ -3089,9 +3093,9 @@ handle_dabr_fault: bl do_break /* * do_break() may have changed the NV GPRS while handling a breakpoint. - * If so, we need to restore them with their updated values. Don't use - * interrupt_return_lite here. + * If so, we need to restore them with their updated values. */ + REST_NVGPRS(r1) b interrupt_return -- 2.7.4