From: Ingo Molnar <mingo@kernel.org>
To: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: linux-kernel@vger.kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
Andi Kleen <ak@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, Maninder Singh <maninder1.s@samsung.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH 0/3] syscalls: clean up stub naming convention
Date: Sun, 8 Apr 2018 10:35:50 +0200 [thread overview]
Message-ID: <20180408083550.32d65b6ra6yca5p7@gmail.com> (raw)
In-Reply-To: <20180407074651.29014-1-linux@dominikbrodowski.net>
* Dominik Brodowski <linux@dominikbrodowski.net> wrote:
> In short (0xffffffff prefix removed, re-ordered):
>
> 810f0af0 t kernel_waitid # common (32/64) kernel helper
>
> <inline> __in_sys_waitid # inlined helper doing actual work
> 810f0be0 t __do_sys_waitid # C func calling inlined helper
>
> <inline> __in_compat_sys_waitid # inlined helper doing actual work
> 810f0d80 t __do_compat_sys_waitid # compat C func calling inlined helper
>
> 810f2080 T __x64_sys_waitid # x64 64-bit-ptregs -> C stub
> 810f20b0 T __ia32_sys_waitid # ia32 32-bit-ptregs -> C stub [unused]
> 810f2470 T __ia32_compat_sys_waitid # ia32 32-bit-ptregs -> compat C stub
> 810f2490 T __x32_compat_sys_waitid # x32 64-bit-ptregs -> compat C stub
Ok, looks pretty clean and nice to me all around, and looking at the highest level
syscall tables the actual calling convention and address encoding is now a _lot_
more obvious at first sight as well.
The "in" part is a tiny bit confusing because it reads like a preposition:
"are we in sys_waitid?".
But I have no better idea, other than we could perhaps use more underscores to
signal the inline helper, instead of the 'in_' prefix:
> 810f0af0 t kernel_waitid # common (32/64) kernel helper
>
> <inline> _____sys_waitid # inlined helper doing actual work
> 810f0be0 t __do_sys_waitid # C func calling inlined helper
>
> <inline> _____compat_sys_waitid # inlined helper doing actual work
> 810f0d80 t __do_compat_sys_waitid # compat C func calling inlined helper
>
> 810f2080 T __x64_sys_waitid # x64 64-bit-ptregs -> C stub
> 810f20b0 T __ia32_sys_waitid # ia32 32-bit-ptregs -> C stub [unused]
> 810f2470 T __ia32_compat_sys_waitid # ia32 32-bit-ptregs -> compat C stub
> 810f2490 T __x32_compat_sys_waitid # x32 64-bit-ptregs -> compat C stub
?
There are some other variants as well, here's the list of all the options I could
think of:
- _____sys_waitid() # ridiculous number of underscores?
- __sys_waitid() # too generic sounding?
- __inline_sys_waitid() # too long?
- __il_sys_waitid() # reminds me of the IL country code ;-)
- __in_sys_waitid() # easy to read as 'are we in syscall?'
None is super convinging - but maybe __inline_sys_waitid is the most natural one.
[ Note, whichever we pick (if we pick a new one), there no need to resend, I can
edit the patches in place if you agree. ]
One more fundamental question: why do we have the __do_sys_waitid() and
__inline_sys_waitid() distinction - aren't the function call signatures the same
with no conversion done?
I.e. couldn't we just do a single, static __do_sys_waitid(), where the compiler
would decide to what extent inlining is justified? This would allow the compiler
to inline all the intermediate code into the stubs themselves.
Or is this a side effect of the error injection feature, which needs to add extra
logic at this intermediate level? That too should be able to use the
__do_sys_waitid() variant though.
> The kbuild test robot barked at an alleged +20038 bytes kernel size regression
> for i386-tinyconfig due to the first patch of this series. That seems to be a
> false positive, as it likely doesn't take into account the change to
> scripts/bloat-o-meter. Moreover, I could not reproduce such a size regression
> on local i386 builds.
Ok, I'll ignore that.
Is UML unaffected by these renames?
Thanks,
Ingo
next prev parent reply other threads:[~2018-04-08 8:35 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-07 7:46 [PATCH 0/3] syscalls: clean up stub naming convention Dominik Brodowski
2018-04-07 7:46 ` [PATCH 1/3] syscalls: clean up syscall " Dominik Brodowski
2018-04-07 7:46 ` [PATCH 2/3] syscalls: clean up compat " Dominik Brodowski
2018-04-07 7:46 ` [PATCH 3/3] syscalls: rename struct pt_regs-based sys_*() to __x64_sys_*() Dominik Brodowski
2018-04-08 8:35 ` Ingo Molnar [this message]
2018-04-08 9:15 ` [PATCH 0/3] syscalls: clean up stub naming convention Dominik Brodowski
2018-04-08 19:59 ` Dominik Brodowski
2018-04-08 20:06 ` [PATCH 4/3] syscalls/x86: adapt syscall_wrapper.h to the new syscall " Dominik Brodowski
2018-04-09 6:49 ` [PATCH 0/3] syscalls: clean up " Ingo Molnar
2018-04-09 6:54 ` Dominik Brodowski
2018-04-09 6:39 ` Ingo Molnar
2018-04-09 19:13 ` Linus Torvalds
2018-04-09 6:45 ` Ingo Molnar
2018-04-09 6:53 ` Dominik Brodowski
2018-04-09 7:06 ` Ingo Molnar
2018-04-09 7:08 ` Dominik Brodowski
2018-04-09 7:34 ` Ingo Molnar
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