arch: riscv: stacktrace: implement arch_stack_walk()

Created the `arch_stack_walk()` function out from the original
`z_riscv_unwind_stack()`. Updated test case accordingly.

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

arch/Kconfig

@@ -111,6 +111,7 @@ config RISCV
 	select ARCH_SUPPORTS_ROM_START if !SOC_SERIES_ESP32C3
 	select ARCH_HAS_CODE_DATA_RELOCATION
 	select ARCH_HAS_THREAD_LOCAL_STORAGE
+	select ARCH_HAS_STACKWALK
 	select IRQ_OFFLOAD_NESTED if IRQ_OFFLOAD
 	select USE_SWITCH_SUPPORTED
 	select USE_SWITCH
@@ -411,6 +412,13 @@ config ARCH_STACKWALK
 	help
 	  Select Y here to enable the `arch_stack_walk()` function for stack unwinding.
 
+config ARCH_STACKWALK_MAX_FRAMES
+	int "Max depth for stack walk function"
+	default 8
+	depends on ARCH_STACKWALK
+	help
+	  Blah
+
 menu "Interrupt Configuration"
 
 config ISR_TABLES_LOCAL_DECLARATION_SUPPORTED

arch/riscv/Kconfig

@@ -41,6 +41,7 @@ config RISCV_ALWAYS_SWITCH_THROUGH_ECALL
 config RISCV_EXCEPTION_STACK_TRACE
 	bool
 	default y
+	depends on ARCH_STACKWALK
 	depends on EXCEPTION_STACK_TRACE
 	imply THREAD_STACK_INFO
 	help

arch/riscv/core/CMakeLists.txt

@@ -25,5 +25,5 @@ zephyr_library_sources_ifdef(CONFIG_RISCV_PMP pmp.c pmp.S)
 zephyr_library_sources_ifdef(CONFIG_THREAD_LOCAL_STORAGE tls.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE userspace.S)
 zephyr_library_sources_ifdef(CONFIG_SEMIHOST semihost.c)
-zephyr_library_sources_ifdef(CONFIG_RISCV_EXCEPTION_STACK_TRACE stacktrace.c)
+zephyr_library_sources_ifdef(CONFIG_ARCH_STACKWALK stacktrace.c)
 zephyr_linker_sources(ROM_START SORT_KEY 0x0vectors vector_table.ld)

arch/riscv/core/stacktrace.c

@@ -14,34 +14,14 @@ LOG_MODULE_DECLARE(os, CONFIG_KERNEL_LOG_LEVEL);
 
 uintptr_t z_riscv_get_sp_before_exc(const z_arch_esf_t *esf);
 
-#if __riscv_xlen == 32
- #define PR_REG "%08" PRIxPTR
-#elif __riscv_xlen == 64
- #define PR_REG "%016" PRIxPTR
-#endif
-
-#define MAX_STACK_FRAMES CONFIG_EXCEPTION_STACK_TRACE_MAX_FRAMES
+#define MAX_STACK_FRAMES                                                                           \
+	MAX(CONFIG_EXCEPTION_STACK_TRACE_MAX_FRAMES, CONFIG_ARCH_STACKWALK_MAX_FRAMES)
 
 struct stackframe {
 	uintptr_t fp;
 	uintptr_t ra;
 };
 
-#ifdef CONFIG_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, const z_arch_esf_t *esf)
 {
 #ifdef CONFIG_THREAD_STACK_INFO
@@ -86,23 +66,19 @@ static inline bool in_text_region(uintptr_t addr)
 }
 
 #ifdef CONFIG_FRAME_POINTER
-void z_riscv_unwind_stack(const z_arch_esf_t *esf)
+static void walk_stackframe(const z_arch_esf_t *esf, bool (*fn)(void *, unsigned long), void *arg)
 {
 	uintptr_t fp = esf->s0;
 	uintptr_t ra;
 	struct stackframe *frame;
 
-	LOG_ERR("call trace:");
-
 	for (int i = 0; (i < MAX_STACK_FRAMES) && (fp != 0U) && in_stack_bound(fp, esf);) {
 		frame = (struct stackframe *)fp - 1;
 		ra = frame->ra;
 		if (in_text_region(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);
+			if (!fn(arg, ra)) {
+				break;
+			}
 			/*
 			 * Increment the iterator only if `ra` is within the text region to get the
 			 * most out of it
@@ -111,36 +87,73 @@ void z_riscv_unwind_stack(const z_arch_esf_t *esf)
 		}
 		fp = frame->fp;
 	}
-
-	LOG_ERR("");
 }
 #else /* !CONFIG_FRAME_POINTER */
-void z_riscv_unwind_stack(const z_arch_esf_t *esf)
+static void walk_stackframe(const z_arch_esf_t *esf, bool (*fn)(void *, unsigned long), void *arg)
 {
 	uintptr_t sp = z_riscv_get_sp_before_exc(esf);
 	uintptr_t ra;
 	uintptr_t *ksp = (uintptr_t *)sp;
 
-	LOG_ERR("call trace:");
-
 	for (int i = 0; (i < MAX_STACK_FRAMES) && ((uintptr_t)ksp != 0U) &&
 			in_stack_bound((uintptr_t)ksp, esf);
 	     ksp++) {
 		ra = *ksp;
 		if (in_text_region(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);
+			if (!fn(arg, ra)) {
+				break;
+			}
 			/*
 			 * Increment the iterator only if `ra` is within the text region to get the
 			 * most out of it
 			 */
 			i++;
 		}
 	}
+}
+#endif /* CONFIG_FRAME_POINTER */
+
+void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie, void *thread,
+		     const void *esf)
+{
+	ARG_UNUSED(thread);
 
+	walk_stackframe(esf, consume_entry, cookie);
+}
+
+#ifdef CONFIG_RISCV_EXCEPTION_STACK_TRACE
+#ifdef CONFIG_EXCEPTION_STACK_TRACE_SYMTAB
+#if __riscv_xlen == 32
+#define PR_REG "%08" PRIxPTR
+#elif __riscv_xlen == 64
+#define PR_REG "%016" PRIxPTR
+#endif
+
+#define LOG_STACK_TRACE(idx, ra, name, offset)                                                     \
+	LOG_ERR("     %2d: ra: " PR_REG " [%s+0x%x]", idx, ra, name, offset)
+#else
+#define LOG_STACK_TRACE(idx, ra, name, offset) LOG_ERR("     %2d: ra: " PR_REG, idx, ra)
+#endif /* CONFIG_EXCEPTION_STACK_TRACE_SYMTAB */
+
+static bool print_trace_address(void *arg, unsigned long ra)
+{
+	int *i = arg;
+#ifdef CONFIG_EXCEPTION_STACK_TRACE_SYMTAB
+	uint32_t offset = 0;
+	const char *name = symtab_find_symbol_name(ra, &offset);
+#endif
+
+	LOG_STACK_TRACE((*i)++, ra, name, offset);
+
+	return true;
+}
+
+void z_riscv_unwind_stack(const z_arch_esf_t *esf)
+{
+	int i = 0;
+
+	LOG_ERR("call trace:");
+	arch_stack_walk(print_trace_address, &i, NULL, esf);
 	LOG_ERR("");
 }
-#endif /* CONFIG_FRAME_POINTER */
+#endif /* CONFIG_RISCV_EXCEPTION_STACK_TRACE */

include/zephyr/arch/arch_interface.h

@@ -1266,7 +1266,7 @@ typedef bool (*stack_trace_consume_fn)(void *cookie, unsigned long addr);
  * ============ ======= ============================================
  */
 void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
-		     k_thread *thread, const void *esf);
+		     void *thread, const void *esf);
 #endif /* CONFIG_ARCH_STACKWALK */
 
 #ifdef __cplusplus

tests/arch/common/stack_unwind/testcase.yaml

@@ -15,8 +15,8 @@ tests:
       type: multi_line
       regex:
         - "E: call trace:"
-        - "E:       0: fp: \\w+   ra: \\w+"
-        - "E:       1: fp: \\w+   ra: \\w+"
+        - "E:       0: ra: \\w+"
+        - "E:       1: ra: \\w+"
   arch.common.stack_unwind.riscv_sp:
     arch_allow: riscv
     integration_platforms:
@@ -26,8 +26,8 @@ tests:
       type: multi_line
       regex:
         - "E: call trace:"
-        - "E:       0: sp: \\w+   ra: \\w+"
-        - "E:       1: sp: \\w+   ra: \\w+"
+        - "E:       0: ra: \\w+"
+        - "E:       1: ra: \\w+"
   arch.common.stack_unwind.x86:
     arch_allow: x86
     extra_configs: