[libcpu][component][debug] add debug info for gdb (#7033)

libcpu/arm/cortex-a/asm-generic.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2006-2023 RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2023-03-12     WangXiaoyao  the first version
+ */
+#ifndef __ASM_GENERIC_H__
+#define __ASM_GENERIC_H__
+
+#define START_POINT(funcname)               \
+    .type funcname, %function;	            \
+    .global funcname;                       \
+    funcname:                               \
+    .cfi_sections .debug_frame, .eh_frame;  \
+    .cfi_startproc;                         \
+    .cfi_undefined lr
+
+#define START_POINT_END(name)   \
+    .cfi_endproc;               \
+    .size name, .-name;
+
+#endif /* __ASM_GENERIC_H__ */

libcpu/arm/cortex-a/cpuport.h

@@ -97,4 +97,6 @@ rt_inline void rt_hw_dsb(void)
     __asm volatile ("dsb":::"memory");
 }
 
+void _thread_start(void);
+
 #endif  /*CPUPORT_H__*/

libcpu/arm/cortex-a/stack.c

@@ -35,7 +35,7 @@ rt_uint8_t *rt_hw_stack_init(void *tentry, void *parameter,
     stack_addr += sizeof(rt_uint32_t);
     stack_addr  = (rt_uint8_t *)RT_ALIGN_DOWN((rt_uint32_t)stack_addr, 8);
     stk      = (rt_uint32_t *)stack_addr;
-    *(--stk) = (rt_uint32_t)tentry;         /* entry point */
+    *(--stk) = (rt_uint32_t)_thread_start;  /* entry point */
     *(--stk) = (rt_uint32_t)texit;          /* lr */
     *(--stk) = 0xdeadbeef;                  /* r12 */
     *(--stk) = 0xdeadbeef;                  /* r11 */
@@ -48,8 +48,8 @@ rt_uint8_t *rt_hw_stack_init(void *tentry, void *parameter,
     *(--stk) = 0xdeadbeef;                  /* r4 */
     *(--stk) = 0xdeadbeef;                  /* r3 */
     *(--stk) = 0xdeadbeef;                  /* r2 */
-    *(--stk) = 0xdeadbeef;                  /* r1 */
-    *(--stk) = (rt_uint32_t)parameter;      /* r0 : argument */
+    *(--stk) = (rt_uint32_t)tentry;         /* r1 : argument 2 for trampoline */
+    *(--stk) = (rt_uint32_t)parameter;      /* r0 : argument 1 */
     /* cpsr */
     if ((rt_uint32_t)tentry & 0x01)
         *(--stk) = SVCMODE | 0x20;          /* thumb mode */

libcpu/arm/cortex-a/start_gcc.S

@@ -673,6 +673,15 @@ rt_hw_clz:
 #define RT_CPUS_NR 1
 #endif
 
+#include "asm-generic.h"
+
+START_POINT(_thread_start)
+    mov     r10, lr
+    blx     r1
+    blx     r10
+    b       .   /* never here */
+START_POINT_END(_thread_start)
+
 .bss
 .align 3     /* align to  2~3=8 */
 svc_stack_n: