linux-kernel - [RFC 03/12] riscv: Switch to CSR

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Message-Id: <20231023082911.23242-4-luxu.kernel@bytedance.com>
Date:   Mon, 23 Oct 2023 16:29:02 +0800
From:   Xu Lu <luxu.kernel@...edance.com>
To:     paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, tglx@...utronix.de, maz@...nel.org,
        anup@...infault.org, atishp@...shpatra.org
Cc:     dengliang.1214@...edance.com, liyu.yukiteru@...edance.com,
        sunjiadong.lff@...edance.com, xieyongji@...edance.com,
        lihangjing@...edance.com, chaiwen.cc@...edance.com,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        Xu Lu <luxu.kernel@...edance.com>
Subject: [RFC 03/12] riscv: Switch to CSR_IE masking when disabling irqs

This commit switch the way of disabling irqs to CSR_IE masking.

After CSR_IE has been made a part of context, now we can safely
switch to CSR_IE masking when disabling irqs.

Signed-off-by: Xu Lu <luxu.kernel@...edance.com>
Signed-off-by: Hangjing Li <lihangjing@...edance.com>
Reviewed-by: Liang Deng <dengliang.1214@...edance.com>
Reviewed-by: Yu Li <liyu.yukiteru@...edance.com>
---
 arch/riscv/include/asm/irqflags.h | 58 +++++++++++++++++++++++++++++++
 arch/riscv/include/asm/ptrace.h   |  4 +++
 arch/riscv/kernel/entry.S         |  7 +++-
 arch/riscv/kernel/head.S          | 10 ++++++
 4 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/irqflags.h b/arch/riscv/include/asm/irqflags.h
index 08d4d6a5b7e9..e0ff37315178 100644
--- a/arch/riscv/include/asm/irqflags.h
+++ b/arch/riscv/include/asm/irqflags.h
@@ -10,6 +10,62 @@
 #include <asm/processor.h>
 #include <asm/csr.h>
 
+#ifdef CONFIG_RISCV_PSEUDO_NMI
+
+static inline void local_irq_switch_on(void)
+{
+	csr_set(CSR_STATUS, SR_IE);
+}
+
+static inline void local_irq_switch_off(void)
+{
+	csr_clear(CSR_STATUS, SR_IE);
+}
+
+/* read interrupt enabled status */
+static inline unsigned long arch_local_save_flags(void)
+{
+	return csr_read(CSR_IE);
+}
+
+/* unconditionally enable interrupts */
+static inline void arch_local_irq_enable(void)
+{
+	csr_set(CSR_IE, irqs_enabled_ie);
+}
+
+/* unconditionally disable interrupts */
+static inline void arch_local_irq_disable(void)
+{
+	csr_clear(CSR_IE, irqs_enabled_ie);
+}
+
+/* get status and disable interrupts */
+static inline unsigned long arch_local_irq_save(void)
+{
+	return csr_read_clear(CSR_IE, irqs_enabled_ie);
+}
+
+/* test flags */
+static inline int arch_irqs_disabled_flags(unsigned long flags)
+{
+	return (flags != irqs_enabled_ie);
+}
+
+/* test hardware interrupt enable bit */
+static inline int arch_irqs_disabled(void)
+{
+	return arch_irqs_disabled_flags(arch_local_save_flags());
+}
+
+/* set interrupt enabled status */
+static inline void arch_local_irq_restore(unsigned long flags)
+{
+	csr_write(CSR_IE, flags);
+}
+
+#else /* CONFIG_RISCV_PSEUDO_NMI */
+
 /* read interrupt enabled status */
 static inline unsigned long arch_local_save_flags(void)
 {
@@ -52,4 +108,6 @@ static inline void arch_local_irq_restore(unsigned long flags)
 	csr_set(CSR_STATUS, flags & SR_IE);
 }
 
+#endif /* !CONFIG_RISCV_PSEUDO_NMI */
+
 #endif /* _ASM_RISCV_IRQFLAGS_H */
diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
index b57d3a6b232f..e552e7fb46f3 100644
--- a/arch/riscv/include/asm/ptrace.h
+++ b/arch/riscv/include/asm/ptrace.h
@@ -178,7 +178,11 @@ static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
 
 static inline int regs_irqs_disabled(struct pt_regs *regs)
 {
+#ifdef CONFIG_RISCV_PSEUDO_NMI
+	return (regs->ie != irqs_enabled_ie);
+#else
 	return !(regs->status & SR_PIE);
+#endif
 }
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 19ba7c4520b9..d1f28dab02f7 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -66,8 +66,13 @@ _save_context:
 	REG_S s4, PT_CAUSE(sp)
 	REG_S s5, PT_TP(sp)
 #ifdef CONFIG_RISCV_PSEUDO_NMI
-	csrr s0, CSR_IE
+	csrrw s0, CSR_IE, x0
 	REG_S s0, PT_IE(sp)
+	andi s1, s1, SR_PIE
+	beqz s1, 1f
+	li s1, SR_IE
+	csrs CSR_STATUS, s1
+1:
 #endif /* CONFIG_RISCV_PSEUDO_NMI */
 
 	/*
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 3710ea5d160f..4f9446defacd 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -169,6 +169,10 @@ secondary_start_sbi:
 	call relocate_enable_mmu
 #endif
 	call setup_trap_vector
+#ifdef CONFIG_RISCV_PSEUDO_NMI
+	li t0, SR_IE
+	csrs CSR_STATUS, t0
+#endif
 	tail smp_callin
 #endif /* CONFIG_SMP */
 
@@ -320,6 +324,12 @@ clear_bss_done:
 #ifdef CONFIG_KASAN
 	call kasan_early_init
 #endif
+
+#ifdef CONFIG_RISCV_PSEUDO_NMI
+	li t0, SR_IE
+	csrs CSR_STATUS, t0
+#endif
+
 	/* Start the kernel */
 	call soc_early_init
 	tail start_kernel
-- 
2.20.1