arch: riscv: stacktrace: handle user threads

Handle user threads stack bound validation in
`in_stack_bound()` to get more accurate traces.

If `CONFIG_PMP_POWER_OF_TWO_ALIGNMENT` is enabled:

```
+------------+ <- thread.arch.priv_stack_start
| Guard      | } Z_RISCV_STACK_GUARD_SIZE
+------------+
| Priv Stack | } CONFIG_PRIVILEGED_STACK_SIZE
+------------+ <- thread.arch.priv_stack_start +
                  CONFIG_PRIVILEGED_STACK_SIZE +
                  Z_RISCV_STACK_GUARD_SIZE
```

otherwise:

```
+------------+ <- thread.stack_obj
| Guard      | } Z_RISCV_STACK_GUARD_SIZE
+------------+
| Priv Stack | } CONFIG_PRIVILEGED_STACK_SIZE
+------------+ <- thread.stack_info.start
| Thread     |
| stack      |
|            |
+............|
| TLS        | } thread.stack_info.delta
+------------+ <- thread.stack_info.start +
                  thread.stack_info.size
```

See: zephyr/include/zephyr/arch/riscv/arch.h

Signed-off-by: Yong Cong Sin <[email protected]>

arch/riscv/core/stacktrace.c

@@ -42,7 +42,7 @@ struct stackframe {
 	LOG_ERR("     %2d: " SFP_FMT PR_REG "   ra: " PR_REG, idx, sfp, ra)
 #endif
 
-static bool in_stack_bound(uintptr_t addr)
+static bool in_stack_bound(uintptr_t addr, const z_arch_esf_t *esf)
 {
 #ifdef CONFIG_THREAD_STACK_INFO
 	uintptr_t start, end;
@@ -54,8 +54,17 @@ static bool in_stack_bound(uintptr_t addr)
 		start = (uintptr_t)K_KERNEL_STACK_BUFFER(z_interrupt_stacks[cpu_id]);
 		end = start + CONFIG_ISR_STACK_SIZE;
 #ifdef CONFIG_USERSPACE
-		/* TODO: handle user threads */
-#endif
+	} else if (((esf->mstatus & MSTATUS_MPP) == PRV_U) &&
+		   ((_current->base.user_options & K_USER) != 0)) {
+		/* See: zephyr/include/zephyr/arch/riscv/arch.h */
+		if (IS_ENABLED(CONFIG_PMP_POWER_OF_TWO_ALIGNMENT)) {
+			start = _current->arch.priv_stack_start - CONFIG_PRIVILEGED_STACK_SIZE;
+			end = _current->arch.priv_stack_start;
+		} else {
+			start = _current->stack_info.start - CONFIG_PRIVILEGED_STACK_SIZE;
+			end = _current->stack_info.start;
+		}
+#endif /* CONFIG_USERSPACE */
 	} else {
 		start = _current->stack_info.start;
 		end = Z_STACK_PTR_ALIGN(_current->stack_info.start + _current->stack_info.size);
@@ -64,6 +73,7 @@ static bool in_stack_bound(uintptr_t addr)
 	return (addr >= start) && (addr < end);
 #else
 	ARG_UNUSED(addr);
+	ARG_UNUSED(esf);
 	return true;
 #endif /* CONFIG_THREAD_STACK_INFO */
 }
@@ -84,7 +94,7 @@ void z_riscv_unwind_stack(const z_arch_esf_t *esf)
 
 	LOG_ERR("call trace:");
 
-	for (int i = 0; (i < MAX_STACK_FRAMES) && (fp != 0U) && in_stack_bound(fp);) {
+	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)) {
@@ -113,8 +123,8 @@ void z_riscv_unwind_stack(const z_arch_esf_t *esf)
 
 	LOG_ERR("call trace:");
 
-	for (int i = 0;
-	     (i < MAX_STACK_FRAMES) && ((uintptr_t)ksp != 0U) && in_stack_bound((uintptr_t)ksp);
+	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)) {