[Patch][newlib][arm] Enable return code with semi-hosting SYS_EXIT_EXTENDED

[Matthew Malcomson]

The _exit function currently passes -1 as a "sig" to the _kill function as an
invalid signal number so that _kill can distinguish between an abort and a
standard exit.

For boards using the SYS_EXIT_EXTENDED semi-hosting operation to return a
status code, this means that the "status" paramter to _exit is ignored and the
return code is always -1.
https://developer.arm.com/docs/100863/latest/semihosting-operations/sys_exit_extended-0x20

This patch puts shared code between _kill and _exit into a new function
_kill_shared that takes the semi-hosting "reason" to use (if semi-hosting is
available) as an argument.

For semi-hosting _kill_shared provides that "reason".

Without the "sig" argument being used to distinguish between a normal and
abnormal exit, the _exit function can provide the return code to be used if the
SYS_EXIT_EXTENDED operation is available.

Hence the exit code can be returned.

Tested with gcc testsuite on arm-none-eabi and no issues.
Ok for master?

PS. I don't have commit rights so if OK can someone commit for me?

Thanks,
Matthew

############### Attachment also inlined for ease of reply ###############


diff --git a/libgloss/arm/_exit.c b/libgloss/arm/_exit.c
index 4a071df58e4c1bc48c64e62d2eae62d33224e806..180541eceb8dbac69e160fdda24af2696a5599a2 100644
--- a/libgloss/arm/_exit.c
+++ b/libgloss/arm/_exit.c
@@ -1,15 +1,16 @@
#include <_ansi.h>
+#include "swi.h"

-int _kill (int, int) __attribute__((__noreturn__));
+int _kill_shared (int, int, int) __attribute__((__noreturn__));
void _exit (int);

void
_exit (int status)
{
- /* There is only one SWI for both _exit and _kill. For _exit, call
- the SWI with the second argument set to -1, an invalid value for
- signum, so that the SWI handler can distinguish the two calls.
- Note: The RDI implementation of _kill throws away both its
- arguments. */
- _kill (status, -1);
+ /* The same SWI is used for both _exit and _kill.
+ For _exit, call the SWI with "reason" set to ADP_Stopped_ApplicationExit
+ to mark a standard exit.
+ Note: The RDI implementation of _kill_shared throws away all its
+ arguments and all implementations ignore the first argument. */
+ _kill_shared (-1, status, ADP_Stopped_ApplicationExit);
}
diff --git a/libgloss/arm/_kill.c b/libgloss/arm/_kill.c
index 34a6ffddfa0e458cb8db3633249d533fbab98a67..69f9856537a9312ff4d6bc1ccdca38e22e7de50f 100644
--- a/libgloss/arm/_kill.c
+++ b/libgloss/arm/_kill.c
@@ -2,16 +2,27 @@
#include <signal.h>
#include "swi.h"

-int _kill (int, int) __attribute__((__noreturn__));
+int _kill_shared (int, int, int) __attribute__((__noreturn__));
+int _kill (int, int);

int
_kill (int pid, int sig)
{
+ if (sig == SIGABRT)
+ _kill_shared (pid, sig, ADP_Stopped_RunTimeError);
+ else
+ _kill_shared (pid, sig, ADP_Stopped_ApplicationExit);
+}
+
+int
+_kill_shared (int pid, int sig, int reason)
+{
(void) pid; (void) sig;
#ifdef ARM_RDI_MONITOR
/* Note: The pid argument is thrown away. */
int block[2];
block[1] = sig;
+ block[0] = reason;
int insn;

#if SEMIHOST_V2
@@ -25,20 +36,6 @@ _kill (int pid, int sig)
insn = AngelSWI_Reason_ReportException;
}

- switch (sig)
- {
- case SIGABRT:
- {
- block[0] = ADP_Stopped_RunTimeError;
- break;
- }
- default:
- {
- block[0] = ADP_Stopped_ApplicationExit;
- break;
- }
- }
-
#if SEMIHOST_V2
if (_has_ext_exit_extended ())
do_AngelSWI (insn, block);