[PATCH] semihosting/arm-compat: Have TARGET_SYS_EXIT[_EXTENDED] return signed

[Philippe Mathieu-Daudé]

Per the "Semihosting for AArch32 and AArch64" spec. v2 (2023Q3) [*]:

  6.5   SYS_EXIT (0x18)
  6.5.2   Entry (64-bit)

    On entry, the PARAMETER REGISTER contains a pointer to
    a two-field argument block:

    . field 1
      The exception type, which is one of the set of reason
      codes in the above tables.

    . field 2
      A subcode, whose meaning depends on the reason code in
      field 1.

    In particular, if field 1 is ADP_Stopped_ApplicationExit
    then field 2 is an exit status code, as passed to the C
    standard library exit() function. [...]

Having libc exit() is declared as:

  LIBRARY
       Standard C Library (libc, -lc)

  SYNOPSIS

       void
       exit(int status);

the status is expected to be signed.

[*] 
https://github.com/ARM-software/abi-aa/blob/2023q3-release/semihosting/semihosting.rst#652entry-64-bit

Fixes: 7446d35e1d ("target-arm/arm-semi.c: SYS_EXIT on A64 takes a parameter 
block")
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
Based-on: <20231004120019.93101-1-philmd@linaro.org>
---
 semihosting/arm-compat-semi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/semihosting/arm-compat-semi.c b/semihosting/arm-compat-semi.c
index 0033a1e018..c419d0c33a 100644
--- a/semihosting/arm-compat-semi.c
+++ b/semihosting/arm-compat-semi.c
@@ -725,7 +725,7 @@ void do_common_semihosting(CPUState *cs)
     case TARGET_SYS_EXIT:
     case TARGET_SYS_EXIT_EXTENDED:
     {
-        uint32_t ret;
+        int ret;
 
         if (common_semi_sys_exit_extended(cs, nr)) {
             /*
-- 
2.41.0