riscv: stack: Support HAVE_SOFTIRQ_ON_OWN_STACK

Add the HAVE_SOFTIRQ_ON_OWN_STACK feature for the IRQ_STACKS config, and
the irq and softirq use the same irq_stack of percpu.

Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230614013018.2168426-3-guoren@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index a8368fe..f515cb1 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -591,11 +591,13 @@ config FPU
          If you don't know what to do here, say Y.
 
 config IRQ_STACKS
-       bool "Independent irq stacks" if EXPERT
+       bool "Independent irq & softirq stacks" if EXPERT
        default y
        select HAVE_IRQ_EXIT_ON_IRQ_STACK
+       select HAVE_SOFTIRQ_ON_OWN_STACK
        help
-         Add independent irq stacks for percpu to prevent kernel stack overflows.
+         Add independent irq & softirq stacks for percpu to prevent kernel stack
+         overflows. We may save some memory footprint by disabling IRQ_STACKS.
 
 endmenu # "Platform type"
 

diff --git a/arch/riscv/kernel/irq.c b/arch/riscv/kernel/irq.c
index a1dcf8e..d0577cc 100644 (file)
--- a/arch/riscv/kernel/irq.c
+++ b/arch/riscv/kernel/irq.c
@@ -11,6 +11,9 @@
 #include <linux/module.h>
 #include <linux/seq_file.h>
 #include <asm/sbi.h>
+#include <asm/smp.h>
+#include <asm/softirq_stack.h>
+#include <asm/stacktrace.h>
 
 static struct fwnode_handle *(*__get_intc_node)(void);
 
@@ -56,6 +59,38 @@ static void init_irq_stacks(void)
                per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);
 }
 #endif /* CONFIG_VMAP_STACK */
+
+#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
+void do_softirq_own_stack(void)
+{
+#ifdef CONFIG_IRQ_STACKS
+       if (on_thread_stack()) {
+               ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
+                                       + IRQ_STACK_SIZE/sizeof(ulong);
+               __asm__ __volatile(
+               "addi   sp, sp, -"RISCV_SZPTR  "\n"
+               REG_S"  ra, (sp)                \n"
+               "addi   sp, sp, -"RISCV_SZPTR  "\n"
+               REG_S"  s0, (sp)                \n"
+               "addi   s0, sp, 2*"RISCV_SZPTR "\n"
+               "move   sp, %[sp]               \n"
+               "call   __do_softirq            \n"
+               "addi   sp, s0, -2*"RISCV_SZPTR"\n"
+               REG_L"  s0, (sp)                \n"
+               "addi   sp, sp, "RISCV_SZPTR   "\n"
+               REG_L"  ra, (sp)                \n"
+               "addi   sp, sp, "RISCV_SZPTR   "\n"
+               :
+               : [sp] "r" (sp)
+               : "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
+                 "t0", "t1", "t2", "t3", "t4", "t5", "t6",
+                 "memory");
+       } else
+#endif
+               __do_softirq();
+}
+#endif /* CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK */
+
 #else
 static void init_irq_stacks(void) {}
 #endif /* CONFIG_IRQ_STACKS */