[PATCH v5 08/17] common-user: Adjust system call return on FreeBSD

[Richard Henderson]

From: Warner Losh <imp@bsdimp.com>

FreeBSD system calls return positive errno.  On the 4 hosts for
which we have support, error is indicated by the C bit set or clear.

Signed-off-by: Warner Losh <imp@bsdimp.com>
[rth: Rebase on new safe_syscall_base api; add #error check.]
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 common-user/host/aarch64/safe-syscall.inc.S | 12 +++++++++++-
 common-user/host/arm/safe-syscall.inc.S     | 11 +++++++++++
 common-user/host/i386/safe-syscall.inc.S    | 10 ++++++++++
 common-user/host/x86_64/safe-syscall.inc.S  | 10 ++++++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/common-user/host/aarch64/safe-syscall.inc.S 
b/common-user/host/aarch64/safe-syscall.inc.S
index 95c60d8609..d3f065cdef 100644
--- a/common-user/host/aarch64/safe-syscall.inc.S
+++ b/common-user/host/aarch64/safe-syscall.inc.S
@@ -65,12 +65,22 @@ safe_syscall_start:
 safe_syscall_end:
 
        /* code path for having successfully executed the syscall */
-       cmn     x0, #4095
+#if defined(__linux__)
+       /* Linux kernel returns (small) negative errno. */
+       cmn     x0, #4096
+       b.hi    0f
+#elif defined(__FreeBSD__)
+       /* FreeBSD kernel returns positive errno and C bit set. */
        b.cs    1f
+#else
+#error "unsupported os"
+#endif
        ret
 
        /* code path setting errno */
+#ifdef __linux__
 0:     neg     w0, w0                  /* create positive errno */
+#endif
 1:     str     w0, [x11]               /* store errno */
        mov     x0, #-1
        ret
diff --git a/common-user/host/arm/safe-syscall.inc.S 
b/common-user/host/arm/safe-syscall.inc.S
index 17839c6486..328299021d 100644
--- a/common-user/host/arm/safe-syscall.inc.S
+++ b/common-user/host/arm/safe-syscall.inc.S
@@ -82,12 +82,23 @@ safe_syscall_start:
 safe_syscall_end:
 
        /* code path for having successfully executed the syscall */
+#if defined(__linux__)
+       /* Linux kernel returns (small) negative errno. */
        cmp     r0, #-4096
        bhi     0f
+#elif defined(__FreeBSD__)
+       /* FreeBSD kernel returns positive errno and C bit set. */
+       bcs     1f
+#else
+#error "unsupported os"
+#endif
+
 9:     pop     { r4, r5, r6, r7, r8, r9, r10, pc }
 
        /* code path setting errno */
+#ifdef __linux__
 0:     neg     r0, r0          /* create positive errno */
+#endif
 1:     str     r0, [r9]        /* store errno */
        mov     r0, #-1
        b       9b
diff --git a/common-user/host/i386/safe-syscall.inc.S 
b/common-user/host/i386/safe-syscall.inc.S
index ad89521783..c27207492a 100644
--- a/common-user/host/i386/safe-syscall.inc.S
+++ b/common-user/host/i386/safe-syscall.inc.S
@@ -76,8 +76,16 @@ safe_syscall_start:
 safe_syscall_end:
 
        /* code path for having successfully executed the syscall */
+#if defined(__linux__)
+       /* Linux kernel returns (small) negative errno. */
        cmp     $-4095, %eax
        jae     0f
+#elif defined(__FreeBSD__)
+       /* FreeBSD kernel returns positive errno and C bit set. */
+       jc      1f
+#else
+#error "unsupported os"
+#endif
 
 9:     pop     %ebx
        .cfi_remember_state
@@ -97,7 +105,9 @@ safe_syscall_end:
        .cfi_restore_state
 
        /* code path setting errno */
+#ifdef __linux__
 0:     neg     %eax                    /* create positive errno */
+#endif
 1:     mov     8+16(%esp), %ebx        /* load errno pointer */
        mov     %eax, (%ebx)            /* store errno */
        mov     $-1, %eax
diff --git a/common-user/host/x86_64/safe-syscall.inc.S 
b/common-user/host/x86_64/safe-syscall.inc.S
index 9a0c4c93b4..e3f920fa5c 100644
--- a/common-user/host/x86_64/safe-syscall.inc.S
+++ b/common-user/host/x86_64/safe-syscall.inc.S
@@ -75,8 +75,16 @@ safe_syscall_start:
 safe_syscall_end:
 
         /* code path for having successfully executed the syscall */
+#if defined(__linux__)
+       /* Linux kernel returns (small) negative errno. */
         cmp    $-4095, %rax
         jae    0f
+#elif defined(__FreeBSD__)
+       /* FreeBSD kernel returns positive errno and C bit set. */
+       jc      1f
+#else
+#error "unsupported os"
+#endif
 
 9:      pop     %rbp
         .cfi_remember_state
@@ -86,7 +94,9 @@ safe_syscall_end:
         .cfi_restore_state
 
         /* code path setting errno */
+#ifdef __linux__
 0:      neg    %eax                    /* create positive errno */
+#endif
 1:      mov    %eax, (%rbp)            /* store errno */
         mov    $-1, %rax
         jmp    9b
-- 
2.25.1