Re: [RFC v3 4/5] common-user: Adjust system call return on FreeBSD

2021-11-14 Thread Richard Henderson

On 11/13/21 5:56 AM, Warner Losh wrote:

All the *-users generally use the negative errno return codes to signal
errno for a system call.  FreeBSD's system calls, on the other hand,
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 | 8 
  common-user/host/arm/safe-syscall.inc.S | 7 +++
  common-user/host/i386/safe-syscall.inc.S| 9 +
  common-user/host/x86_64/safe-syscall.inc.S  | 9 +
  4 files changed, 33 insertions(+)


Reviewed-by: Richard Henderson 

r~



[RFC v3 4/5] common-user: Adjust system call return on FreeBSD

2021-11-12 Thread Warner Losh
All the *-users generally use the negative errno return codes to signal
errno for a system call.  FreeBSD's system calls, on the other hand,
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 | 8 
 common-user/host/arm/safe-syscall.inc.S | 7 +++
 common-user/host/i386/safe-syscall.inc.S| 9 +
 common-user/host/x86_64/safe-syscall.inc.S  | 9 +
 4 files changed, 33 insertions(+)

diff --git a/common-user/host/aarch64/safe-syscall.inc.S 
b/common-user/host/aarch64/safe-syscall.inc.S
index bc1f5a9792..9f9525fe25 100644
--- a/common-user/host/aarch64/safe-syscall.inc.S
+++ b/common-user/host/aarch64/safe-syscall.inc.S
@@ -64,6 +64,14 @@ safe_syscall_start:
svc 0x0
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+/*
+ * 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
+#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..459e5f87c2 100644
--- a/common-user/host/arm/safe-syscall.inc.S
+++ b/common-user/host/arm/safe-syscall.inc.S
@@ -78,6 +78,13 @@ safe_syscall_start:
swi 0
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+/*
+ * FreeBSD kernel returns C bit set with positive errno.
+ * Encode this for use in bsd-user as -errno:
+ */
+negcs   r0, r0
+#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..ba55a35e92 100644
--- a/common-user/host/i386/safe-syscall.inc.S
+++ b/common-user/host/i386/safe-syscall.inc.S
@@ -75,6 +75,15 @@ safe_syscall_start:
int $0x80
 safe_syscall_end:
/* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+/*
+ * FreeBSD kernel returns C bit set with positive errno.
+ * Encode this for use in bsd-user as -errno:
+ */
+jnb 2f
+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..46c527e058 100644
--- a/common-user/host/x86_64/safe-syscall.inc.S
+++ b/common-user/host/x86_64/safe-syscall.inc.S
@@ -72,6 +72,15 @@ safe_syscall_start:
 syscall
 safe_syscall_end:
 /* code path for having successfully executed the syscall */
+#ifdef __FreeBSD__
+/*
+ * FreeBSD kernel returns C bit set with positive errno.
+ * Encode this for use in bsd-user as -errno:
+ */
+jnb 2f
+neg %rax
+2:
+#endif
 pop %rbp
 .cfi_remember_state
 .cfi_def_cfa_offset 8
-- 
2.33.0