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Re: [ECOS] Calling exit in a Redboot standalone Arm program


I have been testing Pierre's exit patch and ended up rearranging
some parts of it so that the gdb kill command also uses the same
stub exit mechanism. Also, I realized that the call_breakpoint
wrapper was not necessary as I originally thought because the
existing trampoline function already wrapped the target function
in the HAL_ARCH_PROGRAM_NEW_STACK macro. Anyway, here is what the
reworked patch looks like. I'll probably check it in today along
with Pierre's "step into swi" and usermode patches.

--Mark

Index: hal/arm/arch/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/arm/arch/current/ChangeLog,v
retrieving revision 1.89
diff -u -p -5 -r1.89 ChangeLog
--- hal/arm/arch/current/ChangeLog	30 Apr 2003 20:02:41 -0000	1.89
+++ hal/arm/arch/current/ChangeLog	6 May 2003 19:00:12 -0000
@@ -1,5 +1,10 @@
+2003-05-06  Pierre Habraken  <Pierre.Habraken@imag.fr>
+
+	* src/arm_stub.c (target_ins, target_thumb_ins): Added code to
+	enable stepping into swi instructions.
+
 2003-04-30  Jonathan Larmour  <jifl@eCosCentric.com>
 
 	* src/vectors.S (handle_IRQ_or_FIQ): Tweak below to be conditional on
 	__thumb__.
 
Index: hal/arm/arch/current/src/arm_stub.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/arm/arch/current/src/arm_stub.c,v
retrieving revision 1.26
diff -u -p -5 -r1.26 arm_stub.c
--- hal/arm/arch/current/src/arm_stub.c	12 Nov 2002 21:50:39 -0000	1.26
+++ hal/arm/arch/current/src/arm_stub.c	6 May 2003 19:00:12 -0000
@@ -6,11 +6,11 @@
 //
 //========================================================================
 //####ECOSGPLCOPYRIGHTBEGIN####
 // -------------------------------------------
 // This file is part of eCos, the Embedded Configurable Operating System.
-// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
+// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Red Hat, Inc.
 //
 // eCos is free software; you can redistribute it and/or modify it under
 // the terms of the GNU General Public License as published by the Free
 // Software Foundation; either version 2 or (at your option) any later version.
 //
@@ -526,11 +526,16 @@ target_ins(unsigned long *pc, unsigned l
                 // Falls through
                 return (pc+1);
             }
         }
     case 0x3:  // Coprocessor & SWI
-        return (pc+1);
+        if (((ins & 0x03000000) == 0x03000000) && ins_will_execute(ins)) {
+           // SWI
+           return (CYGNUM_HAL_VECTOR_SOFTWARE_INTERRUPT * 4);
+        } else {
+           return (pc+1);
+        }
     default:
         // Never reached - but fixes compiler warning.
         return 0;
     }
 }
@@ -568,14 +573,17 @@ target_thumb_ins(unsigned long pc, unsig
             if (!v5T_semantics())
                 new_pc = MAKE_THUMB_ADDR(new_pc);
         }
         break;
     case 0xd:
-        // Bcc
+        // Bcc | SWI
         // Use ARM function to check condition
         arm_ins = ((unsigned long)(ins & 0x0f00)) << 20;
-        if (ins_will_execute(arm_ins)) {
+        if ((arm_ins & 0xF0000000) == 0xF0000000) {
+            // SWI
+            new_pc = CYGNUM_HAL_VECTOR_SOFTWARE_INTERRUPT * 4;
+        } else if (ins_will_execute(arm_ins)) {
             offset = (ins & 0x00FF) << 1;
             if (ins & 0x0080) offset |= 0xFFFFFE00;  // sign extend
             new_pc = MAKE_THUMB_ADDR((unsigned long)(pc+4) + offset);
         }
         break;
Index: hal/common/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/common/current/ChangeLog,v
retrieving revision 1.91
diff -u -p -5 -r1.91 ChangeLog
--- hal/common/current/ChangeLog	8 Apr 2003 17:14:58 -0000	1.91
+++ hal/common/current/ChangeLog	6 May 2003 19:00:15 -0000
@@ -1,5 +1,15 @@
+2003-05-06  Mark Salter  <msalter@redhat.com>
+
+	* src/hal_stub.c (handle_exception_exit): Call sys_profile_reset from
+	here. Setup to return through return_from_stub() when appropriate.
+	(return_from_stub): New function to call CYGACC_CALL_IF_MONITOR_RETURN
+	from thread context.
+
+	* src/generic-stub.c (__handle_exception): Call exit_vec if
+	hal_syscall_handler returns negative number.
+
 2003-04-08  Mark Salter  <msalter@redhat.com>
 
 	* src/hal_misc.c (hal_default_isr): Allow HAL to override default
 	GDB vector matching test.
 
Index: hal/common/current/src/generic-stub.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/common/current/src/generic-stub.c,v
retrieving revision 1.31
diff -u -p -5 -r1.31 generic-stub.c
--- hal/common/current/src/generic-stub.c	8 Apr 2003 01:13:15 -0000	1.31
+++ hal/common/current/src/generic-stub.c	6 May 2003 19:00:15 -0000
@@ -905,12 +905,15 @@ __handle_exception (void)
 #if defined(CYGSEM_REDBOOT_BSP_SYSCALLS)
   // Temporary support for gnupro bsp SWIs
   if (__is_bsp_syscall())
   {
       sigval = hal_syscall_handler();
-      if (0 == sigval)
+      if (sigval <= 0)
       {
+	  if (sigval < 0)
+	      __process_exit_vec ();
+
 	  if (__init_vec != NULL)
               __init_vec ();
 	  return;
       }
   }
@@ -1434,16 +1437,10 @@ __process_packet (char *packet)
       /* fall through */
     case 'k' :      /* kill the program */
 #ifdef __ECOS__
       hal_flush_output();
 #endif
-#ifdef CYGSEM_REDBOOT_BSP_SYSCALLS_GPROF
-      {   // Reset the timer to default and cancel any callback
-          extern void sys_profile_reset(void);
-          sys_profile_reset();
-      }
-#endif // CYGSEM_REDBOOT_BSP_SYSCALLS_GPROF
       __process_exit_vec ();
       return -1;
 
     case 'r':           /* Reset */
       /* With the next 'k' packet, reset the board */
Index: hal/common/current/src/hal_stub.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/hal/common/current/src/hal_stub.c,v
retrieving revision 1.37
diff -u -p -5 -r1.37 hal_stub.c
--- hal/common/current/src/hal_stub.c	23 May 2002 23:02:49 -0000	1.37
+++ hal/common/current/src/hal_stub.c	6 May 2003 19:00:17 -0000
@@ -6,11 +6,11 @@
 //
 //=============================================================================
 //####ECOSGPLCOPYRIGHTBEGIN####
 // -------------------------------------------
 // This file is part of eCos, the Embedded Configurable Operating System.
-// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
+// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003 Red Hat, Inc.
 //
 // eCos is free software; you can redistribute it and/or modify it under
 // the terms of the GNU General Public License as published by the Free
 // Software Foundation; either version 2 or (at your option) any later version.
 //
@@ -95,11 +95,13 @@
 // Saved registers.
 HAL_SavedRegisters *_hal_registers;
 target_register_t registers[HAL_STUB_REGISTERS_SIZE];
 target_register_t alt_registers[HAL_STUB_REGISTERS_SIZE] ;  // Thread or saved process state
 target_register_t * _registers = registers;                 // Pointer to current set of registers
+#ifndef CYGPKG_REDBOOT
 target_register_t orig_registers[HAL_STUB_REGISTERS_SIZE];  // Registers to get back to original state
+#endif
 
 #if defined(HAL_STUB_HW_WATCHPOINT) || defined(HAL_STUB_HW_BREAKPOINT)
 static int  _hw_stop_reason;   // Reason we were stopped by hw.
 
 //#define HAL_STUB_HW_SEND_STOP_REASON_TEXT
@@ -376,43 +378,66 @@ interruptible(int state)
 
 #ifdef CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT
 int cyg_hal_gdb_break;
 #endif
 
+#ifdef CYGPKG_REDBOOT
+// Trampoline for returning to RedBoot from exception/stub code
+static void
+return_from_stub(int exit_status)
+{
+    CYGACC_CALL_IF_MONITOR_RETURN(exit_status);
+}
+#endif
+
 // Called at stub *kill*
 static void 
 handle_exception_exit( void )
 {
+#ifdef CYGPKG_REDBOOT
+#ifdef CYGSEM_REDBOOT_BSP_SYSCALLS_GPROF
+    {   // Reset the timer to default and cancel any callback
+	extern void sys_profile_reset(void);
+	sys_profile_reset();
+    }
+#endif // CYGSEM_REDBOOT_BSP_SYSCALLS_GPROF
+    set_pc((target_register_t)return_from_stub);
+#else
     int i;
 
     for (i = 0; i < (sizeof(registers)/sizeof(registers[0])); i++)
 	registers[i] = orig_registers[i];
+#endif
 }
 
 // Called at stub *entry*
 static void 
 handle_exception_cleanup( void )
 {
+#ifndef CYGPKG_REDBOOT
     static int orig_registers_set = 0;
+#endif
 
     interruptible(0);
 
     // Expand the HAL_SavedRegisters structure into the GDB register
     // array format.
     HAL_GET_GDB_REGISTERS(&registers[0], _hal_registers);
     _registers = &registers[0];
 
+#ifndef CYGPKG_REDBOOT
     if (!orig_registers_set) {
 	int i;
 	for (i = 0; i < (sizeof(registers)/sizeof(registers[0])); i++)
 	    orig_registers[i] = registers[i];
 	_registers = &orig_registers[0];
 	if (__is_breakpoint_function ())
 	    __skipinst ();
 	_registers = &registers[0];
 	orig_registers_set = 1;
     }
+#endif
 	
 #ifdef HAL_STUB_PLATFORM_STUBS_FIXUP
     // Some architectures may need to fix the PC in case of a partial
     // or fully executed trap instruction. GDB only takes correct action
     // when the PC is pointing to the breakpoint instruction it set.
Index: redboot/current/ChangeLog
===================================================================
RCS file: /cvs/ecos/ecos/packages/redboot/current/ChangeLog,v
retrieving revision 1.107
diff -u -p -5 -r1.107 ChangeLog
--- redboot/current/ChangeLog	24 Apr 2003 03:33:04 -0000	1.107
+++ redboot/current/ChangeLog	6 May 2003 19:00:24 -0000
@@ -1,5 +1,28 @@
+2003-05-06  Mark Salter  <msalter@redhat.com>
+
+	* src/main.c (cyg_start): Clear gdb_active when returning from stub.
+
+2003-05-06  Pierre Habraken  <Pierre.Habraken@imag.fr>
+
+	* cdl/redboot.cdl: Added option
+	CYGOPT_REDBOOT_BSP_SYSCALLS_EXIT_WITHOUT_TRAP for enabling (possibly
+	single shot) programs to exit and return a termination status as
+	their normal behavior (i.e. without raising a SIGTRAP).
+	* src/syscall.c (__do_syscall): Added conditionally compiled code
+	to SYS_exit for returning to RedBoot main loop without raising a
+	SIGTRAP, even when the calling program is not being debugged.
+	* src/main.c (cyg_start): Added code (following Jonathan Larmour's
+	and Mark Salter's suggestions) to RedBoot main loop: a (context)
+	savepoint is created before the thread of control is transferred to
+	gdb stubs (through a trampoline procedure). This savepoint enables
+	the stubs to return control back to the main loop by calling the
+	return_to_redboot procedure (macro CYGACC_CALL_IF_MONITOR_RETURN).
+	Procedure go_trampoline and variables go_saved_context and
+	go_return_status have been respectively renamed	to trampoline,
+	saved_context and return_status.
+
 2003-04-23  Chris Garry <cgarry@sweeneydesign.co.uk>
 	
 	* src/flash.c: Only perform RAM check in fis load command when 
 	CYGSEM_REDBOOT_VALIDATE_USER_RAM_LOADS = 1
 
Index: redboot/current/cdl/redboot.cdl
===================================================================
RCS file: /cvs/ecos/ecos/packages/redboot/current/cdl/redboot.cdl,v
retrieving revision 1.47
diff -u -p -5 -r1.47 redboot.cdl
--- redboot/current/cdl/redboot.cdl	28 Mar 2003 13:49:32 -0000	1.47
+++ redboot/current/cdl/redboot.cdl	6 May 2003 19:00:24 -0000
@@ -859,10 +859,19 @@ cdl_package CYGPKG_REDBOOT {
     
             cdl_interface CYGINT_REDBOOT_BSP_SYSCALLS_GPROF_SUPPORT {
                 display	"Does the HAL support 'gprof' profiling?"
                 no_define
             }
+
+            cdl_option CYGOPT_REDBOOT_BSP_SYSCALLS_EXIT_WITHOUT_TRAP {
+                display "Do not raise SIGTRAP when program exits"
+                default_value 0
+                description "
+                    For some (single shot) newlib based programs,
+                    exiting and returning a termination status may be
+                    the normal expected behavior."
+            }
         }
     
         cdl_component CYGOPT_REDBOOT_FIS_ZLIB_COMMON_BUFFER {
             display     	"Use a common buffer for Zlib and FIS"
             flavor	    	bool
Index: redboot/current/src/main.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/redboot/current/src/main.c,v
retrieving revision 1.44
diff -u -p -5 -r1.44 main.c
--- redboot/current/src/main.c	8 Apr 2003 05:09:06 -0000	1.44
+++ redboot/current/src/main.c	6 May 2003 19:00:24 -0000
@@ -78,13 +78,23 @@ extern void breakpoint(void);
 #endif
 
 // Builtin Self Test (BIST)
 externC void bist(void);
 
-// Return path for code run from a go command
+// Path to code run from a go command or to GDB stubs
+static void trampoline(unsigned long entry);
+
+// Return path for code run from a go command or for GDB stubs
 static void return_to_redboot(int status);
 
+// Address of area where current context is saved before executing
+// trampoline procedure
+static void * saved_context;
+
+// Status returned after trampoline execution
+static int return_status;
+ 
 
 // CLI command processing (defined in this file)
 RedBoot_cmd("version", 
             "Display RedBoot version information",
             "",
@@ -314,15 +324,20 @@ cyg_start(void)
                     __chan = CYGACC_CALL_IF_CONSOLE_PROCS();
                     CYGACC_COMM_IF_CONTROL( *__chan, __COMMCTL_IRQ_DISABLE );
                 }
     
                 CYGACC_CALL_IF_SET_CONSOLE_COMM(cur);
-#ifdef HAL_ARCH_PROGRAM_NEW_STACK
-                HAL_ARCH_PROGRAM_NEW_STACK(breakpoint);
-#else
-                breakpoint();  // Get GDB stubs started, with a proper environment, etc.
-#endif
+
+                // set up a temporary context that will take us to the trampoline
+                HAL_THREAD_INIT_CONTEXT((CYG_ADDRESS)workspace_end,
+                                        breakpoint, trampoline, 0);
+
+                // switch context to trampoline (get GDB stubs started)
+                HAL_THREAD_SWITCH_CONTEXT(&saved_context, &workspace_end);
+
+                gdb_active = false;
+
 		dbgchan = CYGACC_CALL_IF_SET_DEBUG_COMM(CYGNUM_CALL_IF_SET_COMM_ID_QUERY_CURRENT);
 		CYGACC_CALL_IF_SET_CONSOLE_COMM(dbgchan);
             } else 
 #endif // CYGDBG_HAL_DEBUG_GDB_INCLUDE_STUBS
             {
@@ -386,15 +401,12 @@ do_help(int argc, char *argv[])
     cmd = __RedBoot_CMD_TAB__;
     show_help(cmd, &__RedBoot_CMD_TAB_END__, which, "");
     return;
 }
 
-static void * go_saved_context;
-static int go_return_status;
-
 static void
-go_trampoline(unsigned long entry)
+trampoline(unsigned long entry)
 {
     typedef void code_fun(void);
     code_fun *fun = (code_fun *)entry;
     unsigned long oldints;
 
@@ -403,19 +415,21 @@ go_trampoline(unsigned long entry)
 #ifdef HAL_ARCH_PROGRAM_NEW_STACK
     HAL_ARCH_PROGRAM_NEW_STACK(fun);
 #else
     (*fun)();
 #endif
+
+    HAL_THREAD_LOAD_CONTEXT(&saved_context);
 }
 
 static void
 return_to_redboot(int status)
 {
     CYGARC_HAL_SAVE_GP();
 
-    go_return_status = status;
-    HAL_THREAD_LOAD_CONTEXT(&go_saved_context);
+    return_status = status;
+    HAL_THREAD_LOAD_CONTEXT(&saved_context);
     // never returns
 
     // need this to balance above CYGARC_HAL_SAVE_GP on
     // some platforms. It will never run, though.
     CYGARC_HAL_RESTORE_GP();
@@ -498,14 +512,14 @@ do_go(int argc, char *argv[])
     }
     HAL_ICACHE_INVALIDATE_ALL();
     HAL_DCACHE_INVALIDATE_ALL();
 
     // set up a temporary context that will take us to the trampoline
-    HAL_THREAD_INIT_CONTEXT((CYG_ADDRESS)workspace_end, entry, go_trampoline, 0);
+    HAL_THREAD_INIT_CONTEXT((CYG_ADDRESS)workspace_end, entry, trampoline, 0);
 
     // switch context to trampoline
-    HAL_THREAD_SWITCH_CONTEXT(&go_saved_context, &workspace_end);
+    HAL_THREAD_SWITCH_CONTEXT(&saved_context, &workspace_end);
 
     // we get back here by way of return_to_redboot()
 
     // undo the changes we made before switching context
     if (!cache_enabled) {
@@ -515,11 +529,11 @@ do_go(int argc, char *argv[])
 
     CYGACC_COMM_IF_CONTROL(*__chan, __COMMCTL_DISABLE_LINE_FLUSH);
 
     HAL_RESTORE_INTERRUPTS(oldints);
 
-    diag_printf("\nProgram completed with status %d\n", go_return_status);
+    diag_printf("\nProgram completed with status %d\n", return_status);
 }
 
 #ifdef HAL_PLATFORM_RESET
 void
 do_reset(int argc, char *argv[])
Index: redboot/current/src/syscall.c
===================================================================
RCS file: /cvs/ecos/ecos/packages/redboot/current/src/syscall.c,v
retrieving revision 1.9
diff -u -p -5 -r1.9 syscall.c
--- redboot/current/src/syscall.c	31 Jan 2003 16:46:01 -0000	1.9
+++ redboot/current/src/syscall.c	6 May 2003 19:00:24 -0000
@@ -629,16 +629,20 @@ __do_syscall(CYG_ADDRWORD func,         
       case __GET_SHARED:
         *(__shared_t **)arg1 = &__shared_data;
         break;
 
       case SYS_exit:
+	*sig = -1;    // signal exit
+	err = arg1;
+
 	if (gdb_active) {
+#ifdef CYGOPT_REDBOOT_BSP_SYSCALLS_EXIT_WITHOUT_TRAP
+	    __send_exit_status((int)arg1);
+#else
 	    *sig = SIGTRAP;
 	    err = func;
-	} else {
-	    CYGACC_CALL_IF_MONITOR_RETURN(arg1);
-	    // never returns
+#endif // CYGOPT_REDBOOT_BSP_SYSCALLS_EXIT_WITHOUT_TRAP
 	}
 	break;
 
       default:
         return 0;




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