Messages in this thread | | | Date | Thu, 9 Apr 2020 09:47:51 +0200 (CEST) | From | Thorsten Glaser <> | Subject | Re: __X32_SYSCALL_BIT being defined as UL constant breaks userspace |
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On Wed, 8 Apr 2020, Andy Lutomirski wrote:
> One might reasonably ask whether it makes sense for syscall nrs to be > signed at all.
It doesn’t, but it’s probably this way for hysteric raisins.
> But regardless, this breaks userspace and we should fix it. I can > whip up a patch to split it into X32_SYSCALL_BIT (unsigned long) and > __X32_SYSCALL_BIT (uapi, int). Thomas, etc, does this seem
This would help with the issue, thanks.
> reasonable? (For those not following all the machinations, this > change caused some userspace build failures in libseccomp and/or > systemd for reasons that are vaguely silly.)
Not very silly:
printf("%d\n", __NR_mmap);
That with -Wformat and -Werror (or -Werror=format) rightfully warns, as the compiler cannot, on x32 (where int=long), detect that, on architectures where int≠long the constant is int.
Even worse, switching userspace to unsigned long globally would completely hose this on LP64 architectures.
So this is, in my opinion, completely justified. (Disclaimer: I’m not affiliated with systemd and not even running it except udev.)
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