Re: [RFC v2 4/6] common-user: Adjust system call return on FreeBSD

2021-11-10 Thread Warner Losh
On Wed, Nov 10, 2021 at 9:59 AM Richard Henderson <
richard.hender...@linaro.org> wrote:

> On 11/10/21 5:31 PM, Warner Losh wrote:
> > All the *-users generally use the Linux style of negative return codes
> > for errno. FreeBSD returns errno, not -errno. Add ifdefs for FreeBSD to
> > make the adjustment on the 4 hosts that we have support for.
> >
> > Signed-off-by: Warner Losh 
> > ---
> >   common-user/host/aarch64/safe-syscall.inc.S | 5 +
> >   common-user/host/arm/safe-syscall.inc.S | 5 +
> >   common-user/host/i386/safe-syscall.inc.S| 5 +
> >   common-user/host/x86_64/safe-syscall.inc.S  | 5 +
> >   4 files changed, 20 insertions(+)
> >
> > diff --git a/common-user/host/aarch64/safe-syscall.inc.S
> b/common-user/host/aarch64/safe-syscall.inc.S
> > index bc1f5a9792..6584950ccf 100644
> > --- a/common-user/host/aarch64/safe-syscall.inc.S
> > +++ b/common-user/host/aarch64/safe-syscall.inc.S
> > @@ -64,6 +64,11 @@ safe_syscall_start:
> >   svc 0x0
> >   safe_syscall_end:
> >   /* code path for having successfully executed the syscall */
> > +#ifdef __FreeBSD__
> > +b.cc2f  /* Convert to Linux -ERRNO convention */
> > +neg x0, x0
> > +2:
> > +#endif
>
> I think it should be a little odd to mention Linux.
>

Yea, from my view of hacking on Unix and Unix-derived systems for the
last 30 years, Linux is the outlier in returning -errno. However, the
'norms'
have shifted, I guess, so I'm happy with your suggestion...


> How about
>
>  /*
>   * FreeBSD kernel returns C bit set with positive errno.
>   * Encode this for use in bsd-user as -errno:
>   *x0 = !c ? x0 : -x0
>   */
>  csneg  x0, x0, x0, cc
>

Ah, better assembler. Good!


>
> > +++ b/common-user/host/arm/safe-syscall.inc.S
> > @@ -78,6 +78,11 @@ safe_syscall_start:
> >   swi 0
> >   safe_syscall_end:
> >   /* code path for having successfully executed the syscall */
> > +#ifdef __FreeBSD__
> > +bcc 2f
> > +neg r0, r0
>
> negcs   r0, r0
>
> I just can't help myself.  :-)


I can relate... Really :)

I'll rework and resend in the next round.

Warner


Re: [RFC v2 4/6] common-user: Adjust system call return on FreeBSD

2021-11-10 Thread Richard Henderson

On 11/10/21 5:31 PM, Warner Losh wrote:

All the *-users generally use the Linux style of negative return codes
for errno. FreeBSD returns errno, not -errno. Add ifdefs for FreeBSD to
make the adjustment on the 4 hosts that we have support for.

Signed-off-by: Warner Losh 
---
  common-user/host/aarch64/safe-syscall.inc.S | 5 +
  common-user/host/arm/safe-syscall.inc.S | 5 +
  common-user/host/i386/safe-syscall.inc.S| 5 +
  common-user/host/x86_64/safe-syscall.inc.S  | 5 +
  4 files changed, 20 insertions(+)

diff --git a/common-user/host/aarch64/safe-syscall.inc.S 
b/common-user/host/aarch64/safe-syscall.inc.S
index bc1f5a9792..6584950ccf 100644
--- a/common-user/host/aarch64/safe-syscall.inc.S
+++ b/common-user/host/aarch64/safe-syscall.inc.S
@@ -64,6 +64,11 @@ safe_syscall_start:
svc 0x0
  safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+b.cc2f  /* Convert to Linux -ERRNO convention */
+neg x0, x0
+2:
+#endif


I think it should be a little odd to mention Linux.
How about

/*
 * FreeBSD kernel returns C bit set with positive errno.
 * Encode this for use in bsd-user as -errno:
 *x0 = !c ? x0 : -x0
 */
csneg  x0, x0, x0, cc



+++ b/common-user/host/arm/safe-syscall.inc.S
@@ -78,6 +78,11 @@ safe_syscall_start:
swi 0
  safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+bcc 2f
+neg r0, r0


negcs   r0, r0

I just can't help myself.  :-)


r~



[RFC v2 4/6] common-user: Adjust system call return on FreeBSD

2021-11-10 Thread Warner Losh
All the *-users generally use the Linux style of negative return codes
for errno. FreeBSD returns errno, not -errno. Add ifdefs for FreeBSD to
make the adjustment on the 4 hosts that we have support for.

Signed-off-by: Warner Losh 
---
 common-user/host/aarch64/safe-syscall.inc.S | 5 +
 common-user/host/arm/safe-syscall.inc.S | 5 +
 common-user/host/i386/safe-syscall.inc.S| 5 +
 common-user/host/x86_64/safe-syscall.inc.S  | 5 +
 4 files changed, 20 insertions(+)

diff --git a/common-user/host/aarch64/safe-syscall.inc.S 
b/common-user/host/aarch64/safe-syscall.inc.S
index bc1f5a9792..6584950ccf 100644
--- a/common-user/host/aarch64/safe-syscall.inc.S
+++ b/common-user/host/aarch64/safe-syscall.inc.S
@@ -64,6 +64,11 @@ safe_syscall_start:
svc 0x0
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+b.cc2f  /* Convert to Linux -ERRNO convention */
+neg x0, x0
+2:
+#endif
ret
 
 0:
diff --git a/common-user/host/arm/safe-syscall.inc.S 
b/common-user/host/arm/safe-syscall.inc.S
index 88c4958504..85c47387f9 100644
--- a/common-user/host/arm/safe-syscall.inc.S
+++ b/common-user/host/arm/safe-syscall.inc.S
@@ -78,6 +78,11 @@ safe_syscall_start:
swi 0
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+bcc 2f
+neg r0, r0
+2:
+#endif
pop { r4, r5, r6, r7, r8, pc }
 
 1:
diff --git a/common-user/host/i386/safe-syscall.inc.S 
b/common-user/host/i386/safe-syscall.inc.S
index 9e58fc6504..7bb6a98a8b 100644
--- a/common-user/host/i386/safe-syscall.inc.S
+++ b/common-user/host/i386/safe-syscall.inc.S
@@ -75,6 +75,11 @@ safe_syscall_start:
int $0x80
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+jnb 2f  /* Convert to Linux -ERRNO convention */
+neg %eax
+2:
+#endif
pop %ebx
.cfi_remember_state
.cfi_adjust_cfa_offset -4
diff --git a/common-user/host/x86_64/safe-syscall.inc.S 
b/common-user/host/x86_64/safe-syscall.inc.S
index f36992daa3..7d8792c7ef 100644
--- a/common-user/host/x86_64/safe-syscall.inc.S
+++ b/common-user/host/x86_64/safe-syscall.inc.S
@@ -72,6 +72,11 @@ safe_syscall_start:
 syscall
 safe_syscall_end:
 /* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+jnb 2f /* Convert to Linux -ERRNO convention */
+neg %rax
+2:
+#endif
 pop %rbp
 .cfi_remember_state
 .cfi_def_cfa_offset 8
-- 
2.33.0