Also print symbols when printing arm64 registers

When printing arm64 registers because of an exception in the kernel
also print the symbol and offset. This can be used to track down why
the exception occured without needing external tools.

Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32077

(cherry picked from commit 7ec86b66099124a9c2c88613507a10979cb8b191)

1 files changed, 44 insertions, 14 deletions

diff --git a/sys/arm64/arm64/trap.c b/sys/arm64/arm64/trap.c
index 34e3b08b4e75..a8e016d6bb61 100644
--- a/sys/arm64/arm64/trap.c
+++ b/sys/arm64/arm64/trap.c
@@ -25,6 +25,8 @@
  *
  */
 
+#include "opt_ddb.h"
+
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
@@ -68,7 +70,8 @@ __FBSDID("$FreeBSD$");
 #endif
 
 #ifdef DDB
-#include <ddb/db_output.h>
+#include <ddb/ddb.h>
+#include <ddb/db_sym.h>
 #endif
 
 /* Called from exception.S */
@@ -78,6 +81,7 @@ void do_el0_error(struct trapframe *);
 void do_serror(struct trapframe *);
 void unhandled_exception(struct trapframe *);
 
+static void print_gp_register(const char *name, uint64_t value);
 static void print_registers(struct trapframe *frame);
 
 int (*dtrace_invop_jump_addr)(struct trapframe *);
@@ -206,7 +210,7 @@ align_abort(struct thread *td, struct trapframe *frame, uint64_t esr,
 {
 	if (!lower) {
 		print_registers(frame);
-		printf(" far: %16lx\n", far);
+		print_gp_register("far", far);
 		printf(" esr:         %.8lx\n", esr);
 		panic("Misaligned access from kernel space!");
 	}
@@ -232,7 +236,7 @@ external_abort(struct thread *td, struct trapframe *frame, uint64_t esr,
 	}
 
 	print_registers(frame);
-	printf(" far: %16lx\n", far);
+	print_gp_register("far", far);
 	panic("Unhandled EL%d external data abort", lower ? 0: 1);
 }
 
@@ -302,7 +306,7 @@ data_abort(struct thread *td, struct trapframe *frame, uint64_t esr,
 	if (td->td_critnest != 0 || WITNESS_CHECK(WARN_SLEEPOK |
 	    WARN_GIANTOK, NULL, "Kernel page fault") != 0) {
 		print_registers(frame);
-		printf(" far: %16lx\n", far);
+		print_gp_register("far", far);
 		printf(" esr:         %.8lx\n", esr);
 		panic("data abort in critical section or under mutex");
 	}
@@ -335,7 +339,7 @@ bad_far:
 
 			printf("Fatal data abort:\n");
 			print_registers(frame);
-			printf(" far: %16lx\n", far);
+			print_gp_register("far", far);
 			printf(" esr:         %.8lx\n", esr);
 
 #ifdef KDB
@@ -357,17 +361,43 @@ bad_far:
 }
 
 static void
+print_gp_register(const char *name, uint64_t value)
+{
+#if defined(DDB)
+	c_db_sym_t sym;
+	const char *sym_name;
+	db_expr_t sym_value;
+	db_expr_t offset;
+#endif
+
+	printf(" %s: %16lx", name, value);
+#if defined(DDB)
+	/* If this looks like a kernel address try to find the symbol */
+	if (value >= VM_MIN_KERNEL_ADDRESS) {
+		sym = db_search_symbol(value, DB_STGY_ANY, &offset);
+		if (sym != C_DB_SYM_NULL) {
+			db_symbol_values(sym, &sym_name, &sym_value);
+			printf(" (%s + %lx)", sym_name, offset);
+		}
+	}
+#endif
+	printf("\n");
+}
+
+static void
 print_registers(struct trapframe *frame)
 {
+	char name[4];
 	u_int reg;
 
 	for (reg = 0; reg < nitems(frame->tf_x); reg++) {
-		printf(" %sx%d: %16lx\n", (reg < 10) ? " " : "", reg,
-		    frame->tf_x[reg]);
+		snprintf(name, sizeof(name), "%sx%d", (reg < 10) ? " " : "",
+		    reg);
+		print_gp_register(name, frame->tf_x[reg]);
 	}
 	printf("  sp: %16lx\n", frame->tf_sp);
-	printf("  lr: %16lx\n", frame->tf_lr);
-	printf(" elr: %16lx\n", frame->tf_elr);
+	print_gp_register(" lr", frame->tf_lr);
+	print_gp_register("elr", frame->tf_lr);
 	printf("spsr:         %8x\n", frame->tf_spsr);
 }
 
@@ -422,7 +452,7 @@ do_el1h_sync(struct thread *td, struct trapframe *frame)
 			abort_handlers[dfsc](td, frame, esr, far, 0);
 		} else {
 			print_registers(frame);
-			printf(" far: %16lx\n", far);
+			print_gp_register("far", far);
 			printf(" esr:         %.8lx\n", esr);
 			panic("Unhandled EL1 %s abort: %x",
 			    exception == EXCP_INSN_ABORT ? "instruction" :
@@ -457,7 +487,7 @@ do_el1h_sync(struct thread *td, struct trapframe *frame)
 		/* FALLTHROUGH */
 	default:
 		print_registers(frame);
-		printf(" far: %16lx\n", READ_SPECIALREG(far_el1));
+		print_gp_register("far", READ_SPECIALREG(far_el1));
 		panic("Unknown kernel exception %x esr_el1 %lx", exception,
 		    esr);
 	}
@@ -528,7 +558,7 @@ do_el0_sync(struct thread *td, struct trapframe *frame)
 			abort_handlers[dfsc](td, frame, esr, far, 1);
 		else {
 			print_registers(frame);
-			printf(" far: %16lx\n", far);
+			print_gp_register("far", far);
 			printf(" esr:         %.8lx\n", esr);
 			panic("Unhandled EL0 %s abort: %x",
 			    exception == EXCP_INSN_ABORT_L ? "instruction" :
@@ -608,7 +638,7 @@ do_serror(struct trapframe *frame)
 	esr = frame->tf_esr;
 
 	print_registers(frame);
-	printf(" far: %16lx\n", far);
+	print_gp_register("far", far);
 	printf(" esr:         %.8lx\n", esr);
 	panic("Unhandled System Error");
 }
@@ -622,7 +652,7 @@ unhandled_exception(struct trapframe *frame)
 	esr = frame->tf_esr;
 
 	print_registers(frame);
-	printf(" far: %16lx\n", far);
+	print_gp_register("far", far);
 	printf(" esr:         %.8lx\n", esr);
 	panic("Unhandled exception");
 }