diff mbox series

[v4,8/9] common-user: Adjust system call return on FreeBSD

Message ID 20211116110256.365484-9-richard.henderson@linaro.org
State Superseded
Headers show
Series linux-user: simplify safe signal handling | expand

Commit Message

Richard Henderson Nov. 16, 2021, 11:02 a.m. UTC 
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(-)

Comments

Warner Losh Nov. 16, 2021, 8:58 p.m. UTC | #1 
On Tue, Nov 16, 2021 at 4:03 AM Richard Henderson <
richard.henderson@linaro.org> wrote:

> 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..a9382f777e 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. */
> +       jcs     1f
>

I needed to change this to 'jc' and that's all google found for Intel.

+#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..36b7efe2ca 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. */
> +       jcs     1f
>

Likewise.


> +#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
>

I've not yet tested this on my arm/aarch64 systems, but I think it will
work there.

Warner
Richard Henderson Nov. 16, 2021, 9:43 p.m. UTC | #2 
On 11/16/21 9:58 PM, Warner Losh wrote:
>     +#elif defined(__FreeBSD__)
>     +       /* FreeBSD kernel returns positive errno and C bit set. */
>     +       jcs     1f
> 
> 
> I needed to change this to 'jc' and that's all google found for Intel.

Yep, that's me jumping between too many arches in one day.  It's jc/jnc for intel.


r~
Philippe Mathieu-Daudé Nov. 17, 2021, 8:23 a.m. UTC | #3 
On 11/16/21 12:02, Richard Henderson wrote:
> 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 +++++++++++

Can we split this in 2 patches?

>  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(-)
Richard Henderson Nov. 17, 2021, 8:32 a.m. UTC | #4 
On 11/17/21 9:23 AM, Philippe Mathieu-Daudé wrote:
> On 11/16/21 12:02, Richard Henderson wrote:
>> 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 +++++++++++
> 
> Can we split this in 2 patches?
> 
>>   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(-)

Why 2?

They're small enough that I think having them all together is fine, but otherwise why 
wouldn't I split to 4?


r~
Philippe Mathieu-Daudé Nov. 17, 2021, 8:38 a.m. UTC | #5 
On 11/17/21 09:32, Richard Henderson wrote:
> On 11/17/21 9:23 AM, Philippe Mathieu-Daudé wrote:
>> On 11/16/21 12:02, Richard Henderson wrote:
>>> 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 +++++++++++
>>
>> Can we split this in 2 patches?
>>
>>>   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(-)
> 
> Why 2?

Personal brain limitation, it is easier to me when I focus on
one base arch at a time. Previous mips/sparc64 changes are
in different patches.

> They're small enough that I think having them all together is fine, but
> otherwise why wouldn't I split to 4?

4 is even better for my brain, but I think I could force my brain
to focus in 1 hunk at a time in a single patch :)
diff mbox series

Patch

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..a9382f777e 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. */
+	jcs	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..36b7efe2ca 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. */
+	jcs	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