coredump: custom core dump stack is now supported on Xtensa targets

components/espcoredump/include_core_dump/port/riscv/esp_core_dump_port_impl.h

@@ -23,23 +23,39 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Define the type that will be used to describe the current context when
+ * doing a backup of the current stack. This same structure is used to restore the stack.
+ */
+typedef struct {
+    uint32_t sp;
+} core_dump_stack_context_t;
+
 /**
  * @brief Set the stack pointer to the address passed as a parameter.
  * @note This function must be inlined.
  *
  * @param new_sp New stack pointer to set in sp register.
- *
+ * @param old_ctx CPU context, related to SP, to fill. It will be given back when restoring SP.
- * @return Former stack pointer address (sp register value).
  */
-FORCE_INLINE_ATTR void* esp_core_dump_replace_sp(void* new_sp)
+FORCE_INLINE_ATTR void esp_core_dump_replace_sp(void* new_sp, core_dump_stack_context_t* old_ctx)
 {
-    void* current_sp = NULL;
     asm volatile ("mv %0, sp \n\t\
                    mv sp, %1 \n\t\
                   "
-                   : "=&r"(current_sp)
+                   : "=&r"(old_ctx->sp)
                    : "r"(new_sp));
-    return current_sp;
+}
+
+
+/**
+ * @brief Restore the stack pointer that was returned when calling `esp_core_dump_replace_sp()` function.
+ *
+ * @param ctx CPU context, related to SP, to restore.
+ */
+FORCE_INLINE_ATTR void esp_core_dump_restore_sp(core_dump_stack_context_t* old_ctx)
+{
+    asm volatile ("mv sp, %0 \n\t" :: "r"(old_ctx->sp));
 }
 
 #ifdef __cplusplus

components/espcoredump/include_core_dump/port/xtensa/esp_core_dump_port_impl.h

@@ -33,23 +33,75 @@
 extern "C" {
 #endif
 
+/**
+ * @brief Define the type that will be used to describe the current context when
+ * doing a backup of the current stack. This same structure is used to restore the stack.
+ */
+typedef struct {
+    uint32_t sp;
+    uint32_t a0;
+    uint32_t ps;
+    uint32_t windowbase;
+    uint32_t windowstart;
+} core_dump_stack_context_t;
+
 /**
  * @brief Set the stack pointer to the address passed as a parameter.
  * @note This function must be inlined.
  *
  * @param new_sp New stack pointer to set in sp register.
- *
+ * @param old_ctx CPU context, related to SP, to fill. It will be given back when restoring SP.
- * @return Former stack pointer address (sp register value).
  */
-FORCE_INLINE_ATTR void* esp_core_dump_replace_sp(void* new_sp)
+FORCE_INLINE_ATTR void esp_core_dump_replace_sp(void* new_sp, core_dump_stack_context_t* old_ctx)
 {
-    void* current_sp = NULL;
+    /* We have to spill all the windows to the stack first as the new stack pointer
-    asm volatile ("mov %0, sp \n\t\
+     * represents a clean new environment. */
-                  "
+    xthal_window_spill();
-                   : "=&r"(current_sp)
+
-                   :);
+    /* Backup the special registers PS, WindowBase and WindowStart. We will need to restore them later */
+    asm volatile ("mov %0, sp \n" \
+                  "mov %1, a0 \n" \
+                  "rsr.ps %2 \n"\
+                  "rsr.windowbase %3 \n"\
+                  "rsr.windowstart %4 \n"\
+                : "=r"(old_ctx->sp),
+                  "=r"(old_ctx->a0),
+                  "=r"(old_ctx->ps),
+                  "=r"(old_ctx->windowbase),
+                  "=r"(old_ctx->windowstart) :);
+
+    /* Set the new stack */
     SET_STACK(new_sp);
-    return current_sp;
+}
+
+
+/**
+ * @brief Restore the stack pointer that was returned when calling `esp_core_dump_replace_sp()` function.
+ *
+ * @param ctx CPU context, related to SP, to restore.
+ */
+FORCE_INLINE_ATTR void esp_core_dump_restore_sp(core_dump_stack_context_t* old_ctx)
+{
+    /* Start by disabling WindowOverflowEnable bit from PS to make sure we won't get a Window Overflow exception
+     * restoring WindowBase and WindowStart registers */
+    const uint32_t ps_woe = old_ctx->ps & ~(PS_WOE_MASK);
+    asm volatile ( \
+        "wsr.ps %0 \n"\
+        "rsync \n"\
+        "wsr.windowbase %1 \n"\
+        "rsync \n"\
+        "wsr.windowstart %2 \n"\
+        "rsync \n"\
+        "mov sp, %3 \n" \
+        "mov a0, %4 \n" \
+        "wsr.ps %5 \n"\
+        "rsync \n"\
+        :: "r"(ps_woe),
+           "r"(old_ctx->windowbase),
+           "r"(old_ctx->windowstart),
+           "r"(old_ctx->sp),
+           "r"(old_ctx->a0),
+           "r"(old_ctx->ps));
 }
 
 #ifdef __cplusplus

components/espcoredump/src/core_dump_common.c

@@ -57,7 +57,7 @@ extern int _coredump_rtc_fast_end;
 
 static uint8_t s_coredump_stack[ESP_COREDUMP_STACK_SIZE];
 static uint8_t* s_core_dump_sp = NULL;
-static uint8_t* s_core_dump_backup = NULL;
+static core_dump_stack_context_t s_stack_context;
 
 /**
  * @brief Function setting up the core dump stack.
@@ -77,9 +77,9 @@ FORCE_INLINE_ATTR void esp_core_dump_setup_stack(void)
     /* Replace the stack pointer depending on the architecture, but save the
      * current stack pointer, in order to be able too restore it later.
      * This function must be inlined. */
-    s_core_dump_backup = esp_core_dump_replace_sp(s_core_dump_sp);
+    esp_core_dump_replace_sp(s_core_dump_sp, &s_stack_context);
     ESP_COREDUMP_LOGI("Backing up stack @ %p and use core dump stack @ %p",
-                      s_core_dump_backup, esp_cpu_get_sp());
+                      s_stack_context.sp, esp_cpu_get_sp());
 }
 
 /**
@@ -111,8 +111,8 @@ FORCE_INLINE_ATTR void esp_core_dump_report_stack_usage(void)
         s_core_dump_sp - s_coredump_stack - bytes_free, bytes_free);
 
     /* Restore the stack pointer. */
-    ESP_COREDUMP_LOGI("Restoring stack @ %p", s_core_dump_backup);
+    ESP_COREDUMP_LOGI("Restoring stack @ %p", s_stack_context.sp);
-    esp_core_dump_replace_sp(s_core_dump_backup);
+    esp_core_dump_restore_sp(&s_stack_context);
 }
 
 #else

components/xtensa/include/xt_instr_macros.h

@@ -84,11 +84,11 @@
     do { \
         uint32_t sp = (uint32_t)new_sp - SAVE_AREA_OFFSET; \
         *(uint32_t*)(sp - BASE_AREA_SP_OFFSET) = (uint32_t)new_sp; \
+        const uint32_t mask = ~(PS_WOE_MASK | PS_OWB_MASK | PS_CALLINC_MASK); \
         uint32_t tmp1 = 0, tmp2 = 0; \
         asm volatile ( \
           "rsr.ps %1 \n"\
-          "movi %2, ~" XTSTR( PS_WOE_MASK | PS_OWB_MASK | PS_CALLINC_MASK ) " \n"\
+          "and %1, %1, %3 \n"\
-          "and %1, %1, %2 \n"\
           "wsr.ps %1 \n"\
           "rsync \n"\
           " \n"\
@@ -99,6 +99,7 @@
           "wsr.windowstart %1 \n"\
           "rsync \n"\
           " \n"\
+          "movi a0, 0\n" \
           "mov sp, %0 \n"\
           "rsr.ps %1 \n"\
           " \n"\
@@ -107,6 +108,6 @@
           "or %1, %1, %2 \n"\
           "wsr.ps %1 \n"\
           "rsync \n"\
-          : "+r"(sp), "+r"(tmp1), "+r"(tmp2)); \
+          : "+r"(sp), "+r"(tmp1), "+r"(tmp2) : "r"(mask)); \
     } while (0);
 #endif // __ASSEMBLER__