arch: riscv: use symtab to print function name in stack trace

Selecting `CONFIG_EXCEPTION_STACK_TRACE_SYMTAB` will
enable the symtab generation which will be used in the
stack trace to print the function name of the return
address.

Updated the `stack_unwind` test to test the symbols in a
stack trace.

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

arch/riscv/core/stacktrace.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+#include <zephyr/debug/symtab.h>
 #include <zephyr/kernel.h>
 #include <zephyr/kernel_structs.h>
 #include <kernel_internal.h>
@@ -26,6 +27,21 @@ struct stackframe {
 	uintptr_t ra;
 };
 
+#ifdef CONFIG_RISCV_ENABLE_FRAME_POINTER
+#define SFP_FMT "fp: "
+#else
+#define SFP_FMT "sp: "
+#endif
+
+#ifdef CONFIG_EXCEPTION_STACK_TRACE_SYMTAB
+#define LOG_STACK_TRACE(idx, sfp, ra, name, offset)                                                \
+	LOG_ERR("     %2d: " SFP_FMT PR_REG "   ra: " PR_REG " [%s+0x%x]", idx, sfp, ra, name,     \
+		offset)
+#else
+#define LOG_STACK_TRACE(idx, sfp, ra, name, offset)                                                \
+	LOG_ERR("     %2d: " SFP_FMT PR_REG "   ra: " PR_REG, idx, sfp, ra)
+#endif
+
 static bool in_stack_bound(uintptr_t addr)
 {
 #ifdef CONFIG_THREAD_STACK_INFO
@@ -82,7 +98,11 @@ void z_riscv_unwind_stack(const z_arch_esf_t *esf)
 		frame = (struct stackframe *)fp - 1;
 		ra = frame->ra;
 		if (in_text_region(ra)) {
-			LOG_ERR("     %2d: fp: " PR_REG "   ra: " PR_REG, i, fp, ra);
+#ifdef CONFIG_EXCEPTION_STACK_TRACE_SYMTAB
+			uint32_t offset = 0;
+			const char *name = symtab_find_symbol_name(ra, &offset);
+#endif
+			LOG_STACK_TRACE(i, fp, ra, name, offset);
 			/*
 			 * Increment the iterator only if `ra` is within the text region to get the
 			 * most out of it
@@ -112,7 +132,11 @@ void z_riscv_unwind_stack(const z_arch_esf_t *esf)
 	     ksp++) {
 		ra = *ksp;
 		if (in_text_region(ra)) {
-			LOG_ERR("     %2d: sp: " PR_REG "   ra: " PR_REG, i, (uintptr_t)ksp, ra);
+#ifdef CONFIG_EXCEPTION_STACK_TRACE_SYMTAB
+			uint32_t offset = 0;
+			const char *name = symtab_find_symbol_name(ra, &offset);
+#endif
+			LOG_STACK_TRACE(i, (uintptr_t)ksp, ra, name, offset);
 			/*
 			 * Increment the iterator only if `ra` is within the text region to get the
 			 * most out of it

doc/releases/release-notes-3.7.rst

@@ -73,10 +73,15 @@ Architectures
 
 * RISC-V
 
-  * Implemented frame-pointer based stack unwinding.
-
   * The fatal error message triggered from a fault now contains the callee-saved-registers states.
 
+  * Implemented stack unwinding
+
+    * Frame-pointer can be selected to enable precise stack traces at the expense of slightly
+      increased size and decreased speed.
+
+    * Symbol names can be enabled by selecting :kconfig:option:`CONFIG_EXCEPTION_STACK_TRACE_SYMTAB`
+
 * Xtensa
 
 Kernel

subsys/debug/Kconfig

@@ -389,6 +389,15 @@ config EXCEPTION_STACK_TRACE
 	  print a stack trace of function memory addresses when an
 	  exception is reported.
 
+config EXCEPTION_STACK_TRACE_SYMTAB
+	bool "Print function names in the stack trace"
+	select SYMTAB
+	depends on EXCEPTION_STACK_TRACE
+	help
+	  Enable this if you want to print the function names in the
+	  stack trace output. This will generate the symtab and
+	  can consume a lot of ROM if there's a lot of functions.
+
 #
 # Miscellaneous debugging options
 #

tests/arch/common/stack_unwind/testcase.yaml

@@ -50,3 +50,18 @@ tests:
       regex:
         - "E: backtrace  0: fp: \\w+ lr: \\w+"
         - "E: backtrace  1: fp: \\w+ lr: \\w+"
+  arch.common.stack_unwind.symtab:
+    arch_allow:
+      - riscv
+    integration_platforms:
+      - qemu_riscv32
+      - qemu_riscv64
+    extra_args: OVERLAY_CONFIG="enable_fp.conf"
+    harness_config:
+      type: multi_line
+      regex:
+        - "[func1+\\w+]"
+        - "[func2+\\w+]"
+        - "[func1+\\w+]"
+        - "[func2+\\w+]"
+        - "[func1+\\w+]"