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From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>,
	Nicholas Piggin <npiggin@gmail.com>
Subject: [RFC PATCH 25/27] powerpc/64s/exception: remove lite interrupt return
Date: Sun, 15 Sep 2019 11:28:11 +1000	[thread overview]
Message-ID: <20190915012813.29317-26-npiggin@gmail.com> (raw)
In-Reply-To: <20190915012813.29317-1-npiggin@gmail.com>

The difference between lite and regular returns is that the lite case
restores all NVGPRs, whereas lite skips that. This is quite clumsy
though, most interrupts want the NVGPRs saved for debugging, not to
modify in the caller, so the NVGPRs restore is not necessary most of
the time. Restore NVGPRs explicitly for one case that requires it,
and move everything else over to avoiding the restore unless the
interrupt return demands it (e.g., handling a signal).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/entry_64.S       |  4 ----
 arch/powerpc/kernel/exceptions-64s.S | 21 +++++++++++----------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index b2e68f5ca8f7..00173cc904ef 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -452,10 +452,6 @@ _GLOBAL(fast_interrupt_return)
 
 	.balign IFETCH_ALIGN_BYTES
 _GLOBAL(interrupt_return)
-	REST_NVGPRS(r1)
-
-	.balign IFETCH_ALIGN_BYTES
-_GLOBAL(interrupt_return_lite)
 	ld	r4,_MSR(r1)
 	andi.	r0,r4,MSR_PR
 	beq	kernel_interrupt_return
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 269edd1460be..1bccc869ebd3 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1507,7 +1507,7 @@ 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
 
@@ -1694,7 +1694,7 @@ 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
 
@@ -1785,7 +1785,7 @@ EXC_COMMON_BEGIN(doorbell_super_common)
 #else
 	bl	unknown_exception
 #endif
-	b	interrupt_return_lite
+	b	interrupt_return
 
 	GEN_KVM doorbell_super
 
@@ -2183,7 +2183,7 @@ EXC_COMMON_BEGIN(h_doorbell_common)
 #else
 	bl	unknown_exception
 #endif
-	b	interrupt_return_lite
+	b	interrupt_return
 
 	GEN_KVM h_doorbell
 
@@ -2213,7 +2213,7 @@ 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
 
@@ -2260,7 +2260,7 @@ 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
 
@@ -3013,7 +3013,7 @@ 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
@@ -3027,10 +3027,11 @@ do_hash_page:
 handle_page_fault:
 11:	andis.  r0,r5,DSISR_DABRMATCH@h
 	bne-    handle_dabr_fault
+	bl	save_nvgprs
 	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)
@@ -3045,9 +3046,9 @@ 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
 
 
-- 
2.23.0


  parent reply	other threads:[~2019-09-15  2:21 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-15  1:27 [RFC PATCH 00/27] current interrupt series plus scv syscall Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 01/27] powerpc/64s/exception: Introduce INT_DEFINE parameter block for code generation Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 02/27] powerpc/64s/exception: Add GEN_COMMON macro that uses INT_DEFINE parameters Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 03/27] powerpc/64s/exception: Add GEN_KVM " Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 04/27] powerpc/64s/exception: Expand EXC_COMMON and EXC_COMMON_ASYNC macros Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 05/27] powerpc/64s/exception: Move all interrupt handlers to new style code gen macros Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 06/27] powerpc/64s/exception: Remove old INT_ENTRY macro Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 07/27] powerpc/64s/exception: Remove old INT_COMMON macro Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 08/27] powerpc/64s/exception: Remove old INT_KVM_HANDLER Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 09/27] powerpc/64s/exception: Add ISIDE option Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 10/27] powerpc/64s/exception: move real->virt switch into the common handler Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 11/27] powerpc/64s/exception: move soft-mask test to common code Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 12/27] powerpc/64s/exception: move KVM " Nicholas Piggin
2019-09-15  1:27 ` [RFC PATCH 13/27] powerpc/64s/exception: remove confusing IEARLY option Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 14/27] powerpc/64s/exception: remove the SPR saving patch code macros Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 15/27] powerpc/64s/exception: trim unused arguments from KVMTEST macro Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 16/27] powerpc/64s/exception: hdecrementer avoid touching the stack Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 17/27] powerpc/64s/exception: re-inline some handlers Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 18/27] powerpc/64s/exception: Clean up SRR specifiers Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 19/27] powerpc/64s/exception: add more comments for interrupt handlers Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 20/27] powerpc/64s/exception: only test KVM in SRR interrupts when PR KVM is supported Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 21/27] powerpc/64s/exception: soft nmi interrupt should not use ret_from_except Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 22/27] powerpc/64: system call remove non-volatile GPR save optimisation Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 23/27] powerpc/64: system call implement the bulk of the logic in C Nicholas Piggin
2019-10-02  8:21   ` Michal Suchánek
2019-10-02  3:10     ` Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 24/27] powerpc/64s: interrupt return " Nicholas Piggin
2019-10-02  8:20   ` Michal Suchánek
2019-09-15  1:28 ` Nicholas Piggin [this message]
2019-09-15  1:28 ` [RFC PATCH 26/27] powerpc/64s/exception: treat NIA below __end_interrupts as soft-masked Nicholas Piggin
2019-09-15  1:28 ` [RFC PATCH 27/27] powerpc/64s: system call support for scv/rfscv instructions Nicholas Piggin
2019-10-02  8:21   ` Michal Suchánek
2019-10-02  8:20 ` [RFC PATCH 00/27] current interrupt series plus scv syscall Michal Suchánek
2019-10-02  3:13   ` Nicholas Piggin
2019-10-30 12:55     ` Michal Suchánek

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