Re: [patch 16/18] x86/entry: Get rid of the sys_ni_syscall() indirection

[H. Peter Anvin]

On October 23, 2026 6:09:07 AM PDT, Thomas Gleixner <tglx at kernel.org> wrote:
>On Thu, Oct 22 2026 at 17:22, H. Peter Anvin wrote:
>> On October 22, 2026 2:34:08 PM PDT, Thomas Gleixner <tglx at kernel.org> wrote:
>>>-static __always_inline void do_syscall_x32(struct pt_regs *regs, unsigned long nr)
>>>+static __always_inline bool do_syscall_x32(struct pt_regs *regs, unsigned long nr)
>>> {
>>>+	if (!IS_ENABLED(CONFIG_X86_X32_ABI))
>>>+		return false;
>>>+
>>>+	/* Preserve the historic insanity of treating -1 special on x32 */
>>>+	if (nr == ULONG_MAX)
>>>+		return true;
>>
>> It was never limited to x32...
>
>Tired brain misread the test output:
>
>[RUN]   Running tests under ptrace: modifying the default return
>[RUN]       Checking system calls with msb = 0 (0x0)
>[OK]                x32 syscalls 0:-64..-2 returned -ENOSYS as expected
>[OK]                x32 syscall 0:-1 returned MODIFIED_BY_PTRACE as expected
>[OK]                x64 syscalls 0:-64..-1 returned -ENOSYS as expected
>
>But that's because the "-1" on x32 is actually 0xFFFFFFFF while on x64
>it's 0x7FFFFFFF.
>
>The whole mess comes from using -1 as indicator for syscall abort which
>is undistinguishable from a syscall(nr=-1).
>
>Bah. Let me restore this nonsense.
>
>Thanks,
>
>        tglx
>
>
>

Yeah, that was always a WTF.