Re: [RFC 4/4] common-user: Allow return codes to be adjusted after sytsem call

[Richard Henderson]

On 11/8/21 3:37 AM, Warner Losh wrote:
> All the *-users generally use the Linux style of negative return codes
> for errno. However, other systems, like FreeBSD, have a different
> convention. Allow those systems to insert code after the syscall that
> adjusts the return value of the system call to match the native linux
> format.
>
> Signed-off-by: Warner Losh <imp@bsdimp.com>
> ---
>   common-user/host/aarch64/safe-syscall.inc.S | 1 +
>   common-user/host/arm/safe-syscall.inc.S     | 1 +
>   common-user/host/i386/safe-syscall.inc.S    | 1 +
>   common-user/host/ppc64/safe-syscall.inc.S   | 1 +
>   common-user/host/riscv/safe-syscall.inc.S   | 1 +
>   common-user/host/s390x/safe-syscall.inc.S   | 1 +
>   common-user/host/x86_64/safe-syscall.inc.S  | 1 +
>   linux-user/safe-syscall.S                   | 1 +
>   8 files changed, 8 insertions(+)
>
> diff --git a/common-user/host/aarch64/safe-syscall.inc.S 
> b/common-user/host/aarch64/safe-syscall.inc.S
> index bc1f5a9792..81d83e8e79 100644
> --- a/common-user/host/aarch64/safe-syscall.inc.S
> +++ b/common-user/host/aarch64/safe-syscall.inc.S
> @@ -64,6 +64,7 @@ safe_syscall_start:
>         svc     0x0
>   safe_syscall_end:
>         /* code path for having successfully executed the syscall */
> +       ADJUST_SYSCALL_RETCODE
>         ret
>   
>   0:

Not sure about this, really.  Is it really that much cleaner to insert this than create 
separate 10-line files, with the adjustment included?


r~