linux-kernel - [PATCH 2/3] RISC-V: Move cpuid to hartid mapping to SMP.

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Message-Id: <1545865741-22795-3-git-send-email-atish.patra@wdc.com>
Date:   Wed, 26 Dec 2018 15:09:00 -0800
From:   Atish Patra <atish.patra@....com>
To:     linux-riscv@...ts.infradead.org
Cc:     Atish Patra <atish.patra@....com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup@...infault.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Dmitriy Cherkasov <dmitriy@...-tech.org>,
        Jason Cooper <jason@...edaemon.net>,
        linux-kernel@...r.kernel.org, Marc Zyngier <marc.zyngier@....com>,
        Michael Clark <michaeljclark@....com>,
        Palmer Dabbelt <palmer@...ive.com>,
        Patrick Stählin <me@...ki.ch>,
        Rob Herring <robh@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Damien Le Moal <Damien.LeMoal@....com>
Subject: [PATCH 2/3] RISC-V: Move cpuid to hartid mapping to SMP.

Currently, logical CPU id to physical hartid mapping is
defined for both smp and non-smp configurations. This
is not required as we need this only for smp configuration.
The mapping function can define directly boot_cpu_hartid
for non-smp usecase.

The reverse mapping function i.e. hartid to cpuid can be called
for any valid but not booted harts. So it should return default
cpu 0 only if it is a boot hartid

Signed-off-by: Atish Patra <atish.patra@....com>
---
 arch/riscv/include/asm/smp.h | 13 +++++++++++--
 arch/riscv/kernel/setup.c    |  2 ++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
index 41aa73b4..8f30300f 100644
--- a/arch/riscv/include/asm/smp.h
+++ b/arch/riscv/include/asm/smp.h
@@ -22,12 +22,13 @@
 /*
  * Mapping between linux logical cpu index and hartid.
  */
-extern unsigned long __cpuid_to_hartid_map[NR_CPUS];
-#define cpuid_to_hartid_map(cpu)    __cpuid_to_hartid_map[cpu]
 
+extern unsigned long boot_cpu_hartid;
 struct seq_file;
 
 #ifdef CONFIG_SMP
+extern unsigned long __cpuid_to_hartid_map[NR_CPUS];
+#define cpuid_to_hartid_map(cpu)    __cpuid_to_hartid_map[cpu]
 
 /* print IPI stats */
 void show_ipi_stats(struct seq_file *p, int prec);
@@ -58,7 +59,15 @@ static inline void show_ipi_stats(struct seq_file *p, int prec)
 
 static inline int riscv_hartid_to_cpuid(int hartid)
 {
+	if (hartid == boot_cpu_hartid)
 		return 0;
+	else
+		return -1;
+}
+static inline unsigned long cpuid_to_hartid_map(int cpu)
+{
+
+	return boot_cpu_hartid;
 }
 
 static inline void riscv_cpuid_to_hartid_mask(const struct cpumask *in,
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 2c290e6a..bd4d7b85 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -83,6 +83,7 @@ EXPORT_SYMBOL(empty_zero_page);
 atomic_t hart_lottery;
 unsigned long boot_cpu_hartid;
 
+#ifdef CONFIG_SMP
 unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
 	[0 ... NR_CPUS-1] = INVALID_HARTID
 };
@@ -91,6 +92,7 @@ void __init smp_setup_processor_id(void)
 {
 	cpuid_to_hartid_map(0) = boot_cpu_hartid;
 }
+#endif
 
 #ifdef CONFIG_BLK_DEV_INITRD
 static void __init setup_initrd(void)
-- 
2.7.4