Re: [PATCH v3 08/49] semihosting: Inline set_swi_errno into common_semi_cb

[Peter Maydell]

On Mon, 23 May 2022 at 15:58, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> On 5/23/22 03:58, Peter Maydell wrote:
> > On Sat, 21 May 2022 at 01:04, Richard Henderson
> > <richard.henderson@linaro.org> wrote:
> >>
> >> Do not store 'err' into errno only to read it back immediately.
> >> Use 'ret' for the return value, not 'reg0'.
> >>
> >> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> >> ---
> >>   semihosting/arm-compat-semi.c | 19 ++++++++++---------
> >>   1 file changed, 10 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/semihosting/arm-compat-semi.c b/semihosting/arm-compat-semi.c
> >> index c6bfd4d1ba..b00ed2c6d1 100644
> >> --- a/semihosting/arm-compat-semi.c
> >> +++ b/semihosting/arm-compat-semi.c
> >> @@ -290,28 +290,29 @@ static target_ulong common_semi_syscall_len;
> >>
> >>   static void common_semi_cb(CPUState *cs, target_ulong ret, target_ulong 
> >> err)
> >>   {
> >> -    target_ulong reg0 = common_semi_arg(cs, 0);
> >> -
> >>       if (ret == (target_ulong)-1) {
> >> -        errno = err;
> >> -        set_swi_errno(cs, -1);
> >> -        reg0 = ret;
> >> +#ifdef CONFIG_USER_ONLY
> >> +        TaskState *ts = cs->opaque;
> >> +        ts->swi_errno = err;
> >> +#else
> >> +        syscall_err = err;
> >> +#endif
> >>       } else {
> >>           /* Fixup syscalls that use nonstardard return conventions.  */
> >> +        target_ulong reg0 = common_semi_arg(cs, 0);
> >
> > This should be "ret = ", right? (Otherwise I think this fails to
> > compile. I assume that some later patch has this fix in it.)
>
> Eh?  No, we're extracting argument reg 0, and then switching on it.
> Why would it not compile -- I've moved the whole declaration down.

Yes, you're right -- I misread the diff as doing a rename of
'reg0' to 'ret', but these are different variables and both
present both before and after the change.

-- PMM