linux-kernel - Re: [linus:master] [x86/entry] be5341eb0d: WARNING:CPU:#PID:#at_int80

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Date: Tue, 19 Dec 2023 15:15:07 -0800
From: Linus Torvalds <torvalds@...uxfoundation.org>
To: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Borislav Petkov <bp@...en8.de>, kernel test robot <oliver.sang@...el.com>, 
	Thomas Gleixner <tglx@...utronix.de>, oe-lkp@...ts.linux.dev, lkp@...el.com, 
	linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...ux.intel.com>, 
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>, xen-devel@...ts.xenproject.org
Subject: Re: [linus:master] [x86/entry] be5341eb0d: WARNING:CPU:#PID:#at_int80_emulation

On Tue, 19 Dec 2023 at 12:17, Linus Torvalds
<torvalds@...uxfoundation.org> wrote:
>
> That said, I still think that just getting rid of this horrid special
> case for posix timers is the right thing, and we should just remove
> that SYS_NI() alias thing entirely.

IOW, something like the attached patch.

It's not extensively tested, but hey, the diffstat looks nice:

  arch/arm64/include/asm/syscall_wrapper.h |  4 ---
  arch/riscv/include/asm/syscall_wrapper.h |  5 ----
  arch/s390/include/asm/syscall_wrapper.h  | 13 +--------
  arch/x86/include/asm/syscall_wrapper.h   | 34 +++---------------------
  kernel/sys_ni.c                          | 14 ++++++++++
  kernel/time/posix-stubs.c                | 45 --------------------------------
  6 files changed, 19 insertions(+), 96 deletions(-)

and it builds in at least a *couple* of configurations, including with
CONFIG_POSIX_TIMERS disabled.

I did *not* check whether it might fix the warning, since I doubt my
user space would even boot without that posix timer support (actually,
honestly, because I'm just lazy and "it _looks_ fine to me" was the
main real thing).

But that SYS_NI() thing really does deserve to die, as it was purely
used as a hack for some random timer system calls.

Comments?

            Linus

View attachment "patch.diff" of type "text/x-patch" (10456 bytes)