Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
IronPort-SDR: HRozAmFiV/7Gzc7ZPJJ0YxLbB6LZFQ+tz+7aHvI3pHzEAu5KhKJPPYhWPLifMo6RVWvsBYog6d
 5ZDhOGuJgUXzBR1BkPSyx8PDzo1W1mhOUe1Xb15Wr2YDJjDUPcTNay2Xl9ELynzWifFdvGU5xy
 U3NEePKAe8oXRPjwWwulqgptc0FRm0lXcIfvcnGrw2ILSAz/9JDlIRu7Q2Wmpg/PA5mwh4U0R7
 TN6iKImALwa/h788kBNYfOyHTx85aBQrz3L38/juAICQaHxa/oqTDhZL/x5B8zlR+R25aNr6Z8
 UBk=
From:   Anup Patel <anup.patel@wdc.com>
To:     Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <marc.zyngier@arm.com>
Cc:     Atish Patra <atish.patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        Anup Patel <anup@brainfault.org>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        Anup Patel <anup.patel@wdc.com>
Subject: [PATCH v4 1/5] RISC-V: self-contained IPI handling routine
Date:   Mon,  9 Mar 2020 16:32:07 +0530
Message-Id: <20200309110211.91130-2-anup.patel@wdc.com>
In-Reply-To: <20200309110211.91130-1-anup.patel@wdc.com>
References: <20200309110211.91130-1-anup.patel@wdc.com>
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-MessageSentRepresentingType: 1
Received: from wdc.com (106.51.22.61) by MAXPR01CA0071.INDPRD01.PROD.OUTLOOK.COM (2603:1096:a00:49::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.2793.11 via Frontend Transport; Mon, 9 Mar 2020 11:02:45 +0000
X-Mailer: git-send-email 2.17.1
X-Originating-IP: [106.51.22.61]
X-MS-PublicTrafficType: Email
X-MS-Office365-Filtering-HT: Tenant
X-MS-Office365-Filtering-Correlation-Id: ea943b68-7003-4f44-43dd-08d7c4196823
X-MS-TrafficTypeDiagnostic: MN2PR04MB6685:
X-MS-Exchange-Transport-Forked: True
X-Microsoft-Antispam-PRVS: <MN2PR04MB6685D41F37303A9C83678C698DFE0@MN2PR04MB6685.namprd04.prod.outlook.com>
WDCIPOUTBOUND: EOP-TRUE
X-MS-Oob-TLC-OOBClassifiers: OLM:6790;
X-Forefront-PRVS: 0337AFFE9A
X-Forefront-Antispam-Report: SFV:NSPM;SFS:(10019020)(4636009)(136003)(346002)(366004)(39860400002)(376002)(396003)(199004)(189003)(16526019)(5660300002)(186003)(1076003)(36756003)(2906002)(478600001)(26005)(8886007)(4326008)(55236004)(7696005)(52116002)(8936002)(316002)(81156014)(8676002)(44832011)(81166006)(55016002)(956004)(1006002)(110136005)(86362001)(54906003)(66556008)(66476007)(2616005)(66946007)(6666004)(7416002)(32040200004);DIR:OUT;SFP:1102;SCL:1;SRVR:MN2PR04MB6685;H:MN2PR04MB6061.namprd04.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1;
X-MS-Exchange-SenderADCheck: 1
X-Microsoft-Antispam: BCL:0;
X-Microsoft-Antispam-Message-Info: 78Uvk1jzGZF2Vmy3tLFDFzI19PH0GsNfeAHBbRdqnMy1DYeHHlRyatB9ebEGESlNT37oODJQtJ7VBPcy/hB04xck4ybhvxjcRyQBAv8cF5o7fIKG18jkpxza5HIQ5C1cNX+4aM0Ciiknn7z+dNEkZtiCyBwyBUhXTFr5z0flGjz07X5vWPHlIi7oKO7dHlj7TWIoA390vPRnYvmKlOXVPlpP/vcCUy99dfNnRYs96u5+P3tcVNhRNnbOsWAI5jODGy+G0aTnQ1BSeT50VOMVAdfNI3TjRULhdtlQwlgIR3jT+I5DUe1WixGxyl+GR31aDXD0NwHD99iTOgnGzR2iKMMQZP6fMNaMPfHZh+X74pzEfiFVjxyOo4C4IVM3tzNS6HNtyHGD97/Jkjmr0Fi8ON6DvGidHn4yKs5AktdUlrpvD4fWYINIMquCXR2tbyZW5f94eA5LLeSgPlZ3kG6zD+xxLW0+tZC5C5GUTwERYBPXCqh6z+FNdY4+JyGUeGQm
X-MS-Exchange-AntiSpam-MessageData: dndXmUsYdWzDsyOW+yWNx8kUoviYrLyD4T3zMaLhURgdhKessTpBQtp0WN82kuN9kCoALtYeI8VZPfZNF6RpcMzFhwO6i+UgEWLCCtZw7C6rnEatOE8rKjAAeklr69VmW20jqpZB8rUXN56okwTt2w==
X-OriginatorOrg: wdc.com
X-MS-Exchange-CrossTenant-Network-Message-Id: ea943b68-7003-4f44-43dd-08d7c4196823
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Mar 2020 11:02:49.9570
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: b61c8803-16f3-4c35-9b17-6f65f441df86
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: U4gkWY9QzLfC7TRJt4haYOCDcsWNBQXuxawMYrTu+G6zKIrj4YCEpvYsCPpKXZ63AlgE+DnXDFItPmd++8GSbQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR04MB6685
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Currently, the IPI handling routine riscv_software_interrupt() does
not take any argument and also does not perform irq_enter()/irq_exit().

This patch makes IPI handling routine more self-contained by:
1. Passing "pt_regs *" argument
2. Explicitly doing irq_enter()/irq_exit()
3. Explicitly save/restore "pt_regs *" using set_irq_regs()

With above changes, IPI handling routine does not depend on caller
function to perform irq_enter()/irq_exit() and save/restore of
"pt_regs *" hence its more self-contained. This also enables us
to call IPI handling routine from IRQCHIP drivers.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
 arch/riscv/include/asm/irq.h |  1 -
 arch/riscv/include/asm/smp.h |  3 +++
 arch/riscv/kernel/irq.c      | 16 ++++++++++------
 arch/riscv/kernel/smp.c      | 11 +++++++++--
 4 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/arch/riscv/include/asm/irq.h b/arch/riscv/include/asm/irq.h
index 6e1b0e0325eb..0183e15ace66 100644
--- a/arch/riscv/include/asm/irq.h
+++ b/arch/riscv/include/asm/irq.h
@@ -13,7 +13,6 @@
 #define NR_IRQS         0
 
 void riscv_timer_interrupt(void);
-void riscv_software_interrupt(void);
 
 #include <asm-generic/irq.h>
 
diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index f4c7cfda6b7f..40bb1c15a731 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -28,6 +28,9 @@ void show_ipi_stats(struct seq_file *p, int prec);
 /* SMP initialization hook for setup_arch */
 void __init setup_smp(void);
 
+/* Called from C code, this handles an IPI. */
+void handle_IPI(struct pt_regs *regs);
+
 /* Hook for the generic smp_call_function_many() routine. */
 void arch_send_call_function_ipi_mask(struct cpumask *mask);
 
diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index 345c4f2eba13..bb0bfcd537e7 100644
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -19,12 +19,15 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 
 asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
 {
-	struct pt_regs *old_regs = set_irq_regs(regs);
+	struct pt_regs *old_regs;
 
-	irq_enter();
 	switch (regs->cause & ~CAUSE_IRQ_FLAG) {
 	case RV_IRQ_TIMER:
+		old_regs = set_irq_regs(regs);
+		irq_enter();
 		riscv_timer_interrupt();
+		irq_exit();
+		set_irq_regs(old_regs);
 		break;
 #ifdef CONFIG_SMP
 	case RV_IRQ_SOFT:
@@ -32,19 +35,20 @@ asmlinkage __visible void __irq_entry do_IRQ(struct pt_regs *regs)
 		 * We only use software interrupts to pass IPIs, so if a non-SMP
 		 * system gets one, then we don't know what to do.
 		 */
-		riscv_software_interrupt();
+		handle_IPI(regs);
 		break;
 #endif
 	case RV_IRQ_EXT:
+		old_regs = set_irq_regs(regs);
+		irq_enter();
 		handle_arch_irq(regs);
+		irq_exit();
+		set_irq_regs(old_regs);
 		break;
 	default:
 		pr_alert("unexpected interrupt cause 0x%lx", regs->cause);
 		BUG();
 	}
-	irq_exit();
-
-	set_irq_regs(old_regs);
 }
 
 void __init init_IRQ(void)
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index eb878abcaaf8..1e8f44a47e14 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -121,11 +121,14 @@ static inline void clear_ipi(void)
 		clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 }
 
-void riscv_software_interrupt(void)
+void handle_IPI(struct pt_regs *regs)
 {
+	struct pt_regs *old_regs = set_irq_regs(regs);
 	unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
 	unsigned long *stats = ipi_data[smp_processor_id()].stats;
 
+	irq_enter();
+
 	clear_ipi();
 
 	while (true) {
@@ -136,7 +139,7 @@ void riscv_software_interrupt(void)
 
 		ops = xchg(pending_ipis, 0);
 		if (ops == 0)
-			return;
+			goto done;
 
 		if (ops & (1 << IPI_RESCHEDULE)) {
 			stats[IPI_RESCHEDULE]++;
@@ -158,6 +161,10 @@ void riscv_software_interrupt(void)
 		/* Order data access and bit testing. */
 		mb();
 	}
+
+done:
+	irq_exit();
+	set_irq_regs(old_regs);
 }
 
 static const char * const ipi_names[] = {
-- 
2.17.1