[PATCH v2] xen/riscv: dump GPRS and CSRs on unexpected traps

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Provide more context on the exception state when an unexpected
exception occurs by dumping various Supervisor, Virtual Supervisor
and Hypervisor CSRs, and GPRs pertaining to the trap.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2
 - Address coments about print_csr() macros and dump_csrs().
 - Add dumping of GPRs pertaining to the trap.
---
 xen/arch/riscv/traps.c | 82 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/xen/arch/riscv/traps.c b/xen/arch/riscv/traps.c
index e9c967786312..4e0df698552f 100644
--- a/xen/arch/riscv/traps.c
+++ b/xen/arch/riscv/traps.c
@@ -17,6 +17,13 @@
 #include <asm/traps.h>
 #include <asm/vsbi.h>
 
+#define print_csr(csr) \
+    printk("\t" #csr ": %016lx\n", csr_read(csr));
+
+#define print_gprs(regs, reg1, reg2) \
+    printk("\t%-7s: %016lx %-7s: %016lx\n", \
+           #reg1, (regs)->reg1, #reg2, (regs)->reg2)
+
 /*
  * Initialize the trap handling.
  *
@@ -99,12 +106,87 @@ static const char *decode_cause(unsigned long cause)
     return decode_trap_cause(cause);
 }
 
+static void dump_general_regs(const struct cpu_user_regs *regs)
+{
+    printk("\nDumping GPRs...\n");
+
+    print_gprs(regs, ra, sp);
+    print_gprs(regs, gp, tp);
+    print_gprs(regs, t0, t1);
+    print_gprs(regs, t2, s0);
+    print_gprs(regs, s1, a0);
+    print_gprs(regs, a1, a2);
+    print_gprs(regs, a3, a4);
+    print_gprs(regs, a5, a6);
+    print_gprs(regs, a7, s2);
+    print_gprs(regs, s3, s4);
+    print_gprs(regs, s5, s6);
+    print_gprs(regs, s7, s8);
+    print_gprs(regs, s9, s10);
+    print_gprs(regs, s11, t3);
+    print_gprs(regs, t4, t5);
+    print_gprs(regs, t6, sepc);
+    print_gprs(regs, sstatus, hstatus);
+}
+
+static void dump_csrs(unsigned long cause)
+{
+    unsigned long hstatus;
+
+    printk("\nDumping CSRs...\n");
+
+    printk("Supervisor CSRs\n");
+    print_csr(CSR_STVEC);
+    print_csr(CSR_SATP);
+    print_csr(CSR_SEPC);
+
+    hstatus = csr_read(CSR_HSTATUS);
+
+    printk("\tCSR_STVAL: %016lx%s\n", csr_read(CSR_STVAL),
+           (hstatus & HSTATUS_GVA) ? ", (guest virtual address)" : "");
+
+    printk("\tCSR_SCAUSE: %016lx\n", cause);
+    printk("\t\tDescription: %s\n", decode_cause(cause));
+    print_csr(CSR_SSTATUS);
+
+    printk("\nVirtual Supervisor CSRs\n");
+    print_csr(CSR_VSTVEC);
+    print_csr(CSR_VSATP);
+    print_csr(CSR_VSEPC);
+    print_csr(CSR_VSTVAL);
+    cause = csr_read(CSR_VSCAUSE);
+    printk("\tCSR_VSCAUSE: %016lx\n", cause);
+    printk("\t\tDescription: %s\n", decode_cause(cause));
+    print_csr(CSR_VSSTATUS);
+
+    printk("\nHypervisor CSRs\n");
+
+    printk("\tCSR_HSTATUS: %016lx [%s%s%s%s%s%s ]\n",
+           hstatus,
+           (hstatus & HSTATUS_VTSR) ? " VTSR" : "",
+           (hstatus & HSTATUS_VTVM) ? " VTVM" : "",
+           (hstatus & HSTATUS_HU)   ? " HU"   : "",
+           (hstatus & HSTATUS_SPVP) ? " SPVP" : "",
+           (hstatus & HSTATUS_SPV)  ? " SPV"  : "",
+           (hstatus & HSTATUS_GVA)  ? " GVA"  : "");
+
+    print_csr(CSR_HGATP);
+    print_csr(CSR_HTVAL);
+    print_csr(CSR_HTINST);
+    print_csr(CSR_HEDELEG);
+    print_csr(CSR_HIDELEG);
+    print_csr(CSR_HSTATEEN0);
+}
+
 static void do_unexpected_trap(const struct cpu_user_regs *regs)
 {
     unsigned long cause = csr_read(CSR_SCAUSE);
 
     printk("Unhandled exception: %s\n", decode_cause(cause));
 
+    dump_csrs(cause);
+    dump_general_regs(regs);
+
     die();
 }
 
-- 
2.52.0