riscv: andes: Support Andes supervisor detailed trap cause (sdcause)

Reformed from the following patches on RISCV-Linux-5.4:
- (edf0bb0) Support sdcause
- (7ed459d) Fix sdcause read using wrong register

Reformed from the following patches on ast-v5_4_0-branch:
- (7fca221) riscv: andes: fix make failure with riscv generic defconfig (torvalds#206)

Signed-off-by: Alan Kao <alankao@andestech.com>

Author: NonerKao

arch/riscv/include/asm/ptrace.h

@@ -49,6 +49,11 @@ struct pt_regs {
 	unsigned long status;
 	unsigned long badaddr;
 	unsigned long cause;
+
+#ifdef CONFIG_ARCH_ANDES
+	/* Andes supervisor detailed trap cause */
+	unsigned long sdcause;
+#endif
 	/* a0 value before the syscall */
 	unsigned long orig_a0;
 };

arch/riscv/kernel/asm-offsets.c

@@ -125,6 +125,9 @@ void asm_offsets(void)
 	OFFSET(PT_STATUS, pt_regs, status);
 	OFFSET(PT_BADADDR, pt_regs, badaddr);
 	OFFSET(PT_CAUSE, pt_regs, cause);
+#ifdef CONFIG_ARCH_ANDES
+	OFFSET(PT_SDCAUSE, pt_regs, sdcause);
+#endif
 
 	OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
 

arch/riscv/kernel/entry.S

@@ -16,6 +16,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/errata_list.h>
 #include <linux/sizes.h>
+#include <linux/soc/andes/csr.h>
 
 	.section .irqentry.text, "ax"
 
@@ -151,12 +152,18 @@ SYM_CODE_START(handle_exception)
 	csrr s3, CSR_TVAL
 	csrr s4, CSR_CAUSE
 	csrr s5, CSR_SCRATCH
+#ifdef CONFIG_ARCH_ANDES
+	csrr s6, CSR_SDCAUSE
+#endif
 	REG_S s0, PT_SP(sp)
 	REG_S s1, PT_STATUS(sp)
 	REG_S s2, PT_EPC(sp)
 	REG_S s3, PT_BADADDR(sp)
 	REG_S s4, PT_CAUSE(sp)
 	REG_S s5, PT_TP(sp)
+#ifdef CONFIG_ARCH_ANDES
+	REG_S s6, PT_SDCAUSE(sp)
+#endif
 
 	/*
 	 * Set the scratch register to 0, so that if a recursive exception

arch/riscv/kernel/process.c

@@ -91,8 +91,8 @@ void __show_regs(struct pt_regs *regs)
 	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
 		regs->t5, regs->t6);
 
-	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
-		regs->status, regs->badaddr, regs->cause);
+	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT " sdcause: " REG_FMT "\n",
+		regs->status, regs->badaddr, regs->cause, regs->sdcause);
 }
 void show_regs(struct pt_regs *regs)
 {