arch: riscv: fatal: print csf in z_riscv_fault()

Refactor the csf saving code into a macro and calls it before jumping
to `z_riscv_fault()`, so that callee-saved-registers are printed on
generic CPU exception as well.

Signed-off-by: Yong Cong Sin <yongcong.sin@gmail.com>
Signed-off-by: Yong Cong Sin <ycsin@meta.com>

Author: ycsin

arch/riscv/core/isr.S

@@ -56,6 +56,20 @@
 	RV_I(	sr s9, ___callee_saved_t_s9_OFFSET(sp)		);\
 	RV_I(	sr s10, ___callee_saved_t_s10_OFFSET(sp)	);\
 	RV_I(	sr s11, ___callee_saved_t_s11_OFFSET(sp)	)
+
+/**
+ * Convenience macro to store the caller-saved registers (CSF) on stack,
+ * and link it to the `struct arch_esf`.
+ *  1. Restore the `s0` we saved early in ISR entry so it shows up properly in the CSF.
+ *  2. Allocate space for CSF on current thread stack
+ *  3. Save CSF to the allocated stack
+ *  4. Link the saved CSF to the `struct arch_esf`
+ */
+#define STORE_CSF_IN_ESF(_esf)                                                                     \
+	lr s0, __struct_arch_esf_s0_OFFSET(sp)		;                                          \
+	addi sp, sp, -__callee_saved_t_SIZEOF		;                                          \
+	STORE_CALLEE_SAVED()				;                                          \
+	sr sp __struct_arch_esf_csf_OFFSET(_esf)
 #endif /* CONFIG_EXCEPTION_DEBUG */
 
 	.macro get_current_cpu dst
@@ -383,8 +397,18 @@ no_fp:	/* increment _current->arch.exception_depth */
 	 * no_reschedule to restore stack.
 	 */
 	mv a0, sp
+#ifdef CONFIG_EXCEPTION_DEBUG
+	STORE_CSF_IN_ESF(a0)		;
+
+	call z_riscv_fault
+	/* Restore SP if z_riscv_fault returns before jumping to no_reschedule */
+	addi sp, sp, __callee_saved_t_SIZEOF
+
+	j no_reschedule
+#else
 	la ra, no_reschedule
 	tail z_riscv_fault
+#endif /* CONFIG_EXCEPTION_DEBUG */
 
 is_kernel_syscall:
 	/*
@@ -454,20 +478,7 @@ do_fault:
 1:	mv a1, sp
 
 #ifdef CONFIG_EXCEPTION_DEBUG
-	/*
-	 * Restore the s0 we saved early in ISR entry
-	 * so it shows up properly in the CSF.
-	 */
-	lr s0, __struct_arch_esf_s0_OFFSET(sp)
-
-	/* Allocate space for caller-saved registers on current thread stack */
-	addi sp, sp, -__callee_saved_t_SIZEOF
-
-	/* Save callee-saved registers */
-	STORE_CALLEE_SAVED()		;
-
-	/* Store csf's addr into esf (a1 still holds the pointer to the esf at this point) */
-	sr sp __struct_arch_esf_csf_OFFSET(a1)
+	STORE_CSF_IN_ESF(a1)		;
 #endif /* CONFIG_EXCEPTION_DEBUG */
 	tail z_riscv_fatal_error