[PATCH v11 3/5] xen/riscv: introduce trap_init()

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Note that trap_init() isn't declared with the __init attribute to
avoid removing __init when multi-CPU support for Xen is added.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
Reviewed-by: Alistair Francis <alistair.francis@xxxxxxx>
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Changes in V11:
  - update the commit message
  - add Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Changes in V10:
  - update the commit message
---
Changes in V9:
 - drop inclusion of <asm/mm.h> in setup.c
 - drop #include <public/version.h>
 - ... <xen/bug.h>
 - introduce stub for
   void arch_get_xen_caps(xen_capabilities_info_t *info);

 - resolve rebase conflicts.
---
Changes in V8:
 - nothing changed. only rebase was done.
---
Changes in V7:
 - #define cast_to_bug_frame(addr) ((const struct bug_frame *)(addr)).
 - remove unnecessary comments in trap_init() function.
---
Changes in V6:
 - trap_init() is now called after enabling the MMU.
 - Add additional explanatory comments.
---
Changes in V5:
  - Nothing changed
---
Changes in V4:
  - Nothing changed
---
Changes in V3:
  - Nothing changed
---
Changes in V2:
  - Rename setup_trap_handler() to trap_init().
  - Add Reviewed-by to the commit message.
---
 xen/arch/riscv/include/asm/traps.h |  1 +
 xen/arch/riscv/setup.c             |  3 +++
 xen/arch/riscv/traps.c             | 12 ++++++++++++
 3 files changed, 16 insertions(+)

diff --git a/xen/arch/riscv/include/asm/traps.h 
b/xen/arch/riscv/include/asm/traps.h
index 3fef318478..c30118e095 100644
--- a/xen/arch/riscv/include/asm/traps.h
+++ b/xen/arch/riscv/include/asm/traps.h
@@ -9,6 +9,7 @@
 
 void do_trap(struct cpu_user_regs *cpu_regs);
 void handle_trap(void);
+void trap_init(void);
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/xen/arch/riscv/setup.c b/xen/arch/riscv/setup.c
index e3cb0866d5..a6a29a1508 100644
--- a/xen/arch/riscv/setup.c
+++ b/xen/arch/riscv/setup.c
@@ -8,6 +8,7 @@
 #include <public/version.h>
 
 #include <asm/early_printk.h>
+#include <asm/traps.h>
 
 void arch_get_xen_caps(xen_capabilities_info_t *info)
 {
@@ -23,6 +24,8 @@ void __init noreturn start_xen(unsigned long bootcpu_id,
 {
     remove_identity_mapping();
 
+    trap_init();
+
     printk("All set up\n");
 
     for ( ;; )
diff --git a/xen/arch/riscv/traps.c b/xen/arch/riscv/traps.c
index 37cec40dfa..cb18b30ff2 100644
--- a/xen/arch/riscv/traps.c
+++ b/xen/arch/riscv/traps.c
@@ -12,6 +12,18 @@
 #include <asm/riscv_encoding.h>
 #include <asm/traps.h>
 
+/*
+ * Initialize the trap handling.
+ *
+ * The function is called after MMU is enabled.
+ */
+void trap_init(void)
+{
+    unsigned long addr = (unsigned long)&handle_trap;
+
+    csr_write(CSR_STVEC, addr);
+}
+
 static const char *decode_trap_cause(unsigned long cause)
 {
     static const char *const trap_causes[] = {
-- 
2.45.2