From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: <linux-snps-arc@lists.infradead.org>
Cc: <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Vineet Gupta <Vineet.Gupta1@synopsys.com>
Subject: [PATCH 4/4] ARCv2: entry: Reduce perf intr return path
Date: Tue, 7 Nov 2017 14:13:04 -0800 [thread overview]
Message-ID: <1510092784-19942-5-git-send-email-vgupta@synopsys.com> (raw)
In-Reply-To: <1510092784-19942-1-git-send-email-vgupta@synopsys.com>
In the more likely case of returning to kernel from perf interrupt, do a
fast path returning w/o bothering about CONFIG_PREEMPT etc
However, if returning to user space, need do go thru the usual gyrations,
as check for pending signals is an absolute must.
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/entry-arcv2.h | 2 ++
arch/arc/kernel/entry-arcv2.S | 23 ++++++++++++++++++++++-
2 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h
index 257a68f3c2fe..8b49b327b1f9 100644
--- a/arch/arc/include/asm/entry-arcv2.h
+++ b/arch/arc/include/asm/entry-arcv2.h
@@ -58,6 +58,8 @@
/*------------------------------------------------------------------------*/
.macro INTERRUPT_EPILOGUE called_from
+ ; Assumes STATUS32.Z bit set if return to K
+
.ifnc \called_from, exception
add sp, sp, 12 ; skip BTA/ECR/orig_r0 placeholderss
.endif
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index cc558a25b8fa..9ca1d146426b 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -51,7 +51,7 @@ VECTOR handle_interrupt ; (16) Timer0
VECTOR handle_interrupt ; unused (Timer1)
VECTOR handle_interrupt ; unused (WDT)
VECTOR handle_interrupt ; (19) Inter core Interrupt (IPI)
-VECTOR handle_interrupt ; (20) perf Interrupt
+VECTOR handle_interrupt_pct ; (20) perf Interrupt
VECTOR handle_interrupt ; (21) Software Triggered Intr (Self IPI)
VECTOR handle_interrupt ; unused
VECTOR handle_interrupt ; (23) unused
@@ -97,6 +97,26 @@ ENTRY(handle_interrupt)
END(handle_interrupt)
+ENTRY(handle_interrupt_pct)
+
+ INTERRUPT_PROLOGUE irq
+
+ IRQ_DISABLE
+
+ lr r0, [ICAUSE]
+
+ bl.d arch_do_IRQ
+ mov r1, sp
+
+ ld r0, [sp, PT_status32] ; returning to User/Kernel Mode
+ btst r0, STATUS_U_BIT
+ bnz resume_user_mode_begin
+
+ clri
+ b .Lisr_ret_fast_path_to_k
+
+END(handle_interrupt_pct)
+
;################### Non TLB Exception Handling #############################
ENTRY(EV_SWI)
@@ -224,6 +244,7 @@ debug_marker_l1:
bset.nz r11, r11, AUX_IRQ_ACT_BIT_U ; NZ means U
sr r11, [AUX_IRQ_ACT]
+.Lisr_ret_fast_path_to_k:
INTERRUPT_EPILOGUE irq
rtie
--
2.7.4
next prev parent reply other threads:[~2017-11-07 22:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 22:13 [PATCH 0/4] ARC perf updates Vineet Gupta
2017-11-07 22:13 ` [PATCH 1/4] ARCv2: perf: tweak overflow interrupt Vineet Gupta
2017-11-07 22:13 ` [PATCH 2/4] ARCv2: perf: optimize given that num counters <= 32 Vineet Gupta
2017-11-07 22:13 ` [PATCH 3/4] ARC: perf: avoid vmalloc backed mmap Vineet Gupta
2017-11-07 22:13 ` Vineet Gupta [this message]
2017-11-14 10:28 ` [PATCH 4/4] ARCv2: entry: Reduce perf intr return path Peter Zijlstra
2017-11-14 23:01 ` Vineet Gupta
2017-11-15 10:18 ` Peter Zijlstra
2017-11-17 23:42 ` Vineet Gupta
2017-11-21 23:26 ` Vineet Gupta
2017-11-13 21:30 ` [PATCH 0/4] ARC perf updates Vineet Gupta
2017-11-21 22:09 ` Vineet Gupta
2017-11-21 23:13 ` Peter Zijlstra
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