From fc44cbdbdbdf76fb75e7ad39d20e8b86e1f3c691 Mon Sep 17 00:00:00 2001
From: Ville Juven <ville.juven@unikie.com>
Date: Tue, 28 Mar 2023 13:57:08 +0300
Subject: [PATCH] arch/risc-v: Set Supervisor User Memory (access) for idle
 process too

This has been a long issue for me as it results in random crashes when
asynchronous events occur when the idle process is active.

The problem is that the kernel cannot access user memory, because the CPU
status prevents it.
---
 arch/risc-v/src/common/riscv_getnewintctx.c | 9 +++++++++
 arch/risc-v/src/common/riscv_initialstate.c | 4 ++++
 arch/risc-v/src/common/riscv_internal.h     | 1 +
 3 files changed, 14 insertions(+)

diff --git a/arch/risc-v/src/common/riscv_getnewintctx.c b/arch/risc-v/src/common/riscv_getnewintctx.c
index f1fa4cf3ded..2588ff2841d 100644
--- a/arch/risc-v/src/common/riscv_getnewintctx.c
+++ b/arch/risc-v/src/common/riscv_getnewintctx.c
@@ -70,3 +70,12 @@ uintptr_t riscv_get_newintctx(void)
 #endif
   );
 }
+
+void riscv_set_idleintctx(void)
+{
+  /* Set SUM for idle process if needed */
+
+#ifdef CONFIG_ARCH_USE_MMU
+  SET_CSR(CSR_STATUS, STATUS_SUM);
+#endif
+}
diff --git a/arch/risc-v/src/common/riscv_initialstate.c b/arch/risc-v/src/common/riscv_initialstate.c
index 3c2b5f00e78..802c2103d7a 100644
--- a/arch/risc-v/src/common/riscv_initialstate.c
+++ b/arch/risc-v/src/common/riscv_initialstate.c
@@ -78,6 +78,10 @@ void up_initial_state(struct tcb_s *tcb)
 
       riscv_stack_color(tcb->stack_alloc_ptr, 0);
 #endif /* CONFIG_STACK_COLORATION */
+
+      /* Set idle process' initial interrupt context */
+
+      riscv_set_idleintctx();
       return;
     }
 
diff --git a/arch/risc-v/src/common/riscv_internal.h b/arch/risc-v/src/common/riscv_internal.h
index fbfa3f12fa6..a6602b06aa6 100644
--- a/arch/risc-v/src/common/riscv_internal.h
+++ b/arch/risc-v/src/common/riscv_internal.h
@@ -200,6 +200,7 @@ void riscv_copystate(uintptr_t *dest, uintptr_t *src);
 void riscv_sigdeliver(void);
 int riscv_swint(int irq, void *context, void *arg);
 uintptr_t riscv_get_newintctx(void);
+void riscv_set_idleintctx(void);
 void riscv_exception_attach(void);
 
 #ifdef CONFIG_ARCH_FPU