linux-kernel - [PATCHv2 0/4] syscalls: clean up stub naming convention

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Message-Id: <20180409105145.5364-1-linux@dominikbrodowski.net>
Date:   Mon,  9 Apr 2018 12:51:41 +0200
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     linux-kernel@...r.kernel.org, mingo@...nel.org
Cc:     Dominik Brodowski <linux@...inikbrodowski.net>,
        Al Viro <viro@...iv.linux.org.uk>,
        Andi Kleen <ak@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Brian Gerst <brgerst@...il.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Maninder Singh <maninder1.s@...sung.com>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arch <linux-arch@...r.kernel.org>
Subject: [PATCHv2 0/4] syscalls: clean up stub naming convention

As per the discussion with Ingo, here is an updated patchset on top of tip/asm
to clean up the syscall stub naming convention. Changes to v1 include renames
(__do_ becomes __se_ for sign-extending, __in_ becomes __do_) and more
comments.

For the generic case, we now will have:

t	        kernel_waitid	# common C function (see kernel/exit.c)

i	      __do_sys_waitid	# inlined helper doing the actual work
				# (takes original parameters as declared)

T	      __se_sys_waitid	# sign-extending C function calling inlined
				# helper (takes parameters of type long; casts
				# them to the declared type)

i	__do_compat_sys_waitid	# inlined helper doing the actual work
				# (takes parameters as declared)

T	__se_compat_sys_waitid	# sign-extending C function calling inlined
				# helper (takes parameters of type long, casts
				# them to unsigned long and then to the
				# declared type)

T	            sys_waitid	# alias to __se_sys_waitid() (taking
				# parameters as declared), to be included
				# in syscall table

T	     compat_sys_waitid	# alias to __se_compat_sys_waitid()
				# (taking parameters as declared), to
				# be included in syscall table


For 64-bit x86, kernel_waitid, __do_sys_waitid and __se_sys_waitid are the
same. But instead of sys_waitid and compat_sys_waitid, there are:

T	      __x64_sys_waitid	# x86 64-bit-ptregs -> C stub, calls
				# __se_sys_waitid(); to be included in
				# syscall table

T	     __ia32_sys_waitid	# IA32_EMULATION 32-bit-ptregs -> C stub,
				# calls __se_sys_waitid(); to be included
				# in syscall table unless there is a
				# compat syscall stub [in that case, it is
				# unused]

T     __ia32_compat_sys_waitid	# IA32_EMULATION 32-bit-ptregs -> C stub,
				# calls __se_compat_sys_waitid(); to be
				# included in syscall table

T      __x32_compat_sys_waitid	# x32 64-bit-ptregs -> C stub, calls
				# __se_compat_sys_waitid(); to be included
				# in syscall table

In short (0xffffffff prefix removed, re-ordered):

810f0af0 t            kernel_waitid	# common (32/64) kernel helper

<inline>            __do_sys_waitid	# inlined helper doing actual work
810f0be0 t          __se_sys_waitid	# C func calling inlined helper

<inline>     __do_compat_sys_waitid	# inlined helper doing actual work
810f0d80 t   __se_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

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.

Thanks,
	Dominik


Dominik Brodowski (4):
  syscalls: clean up syscall stub naming convention
  syscalls: clean up compat syscall stub naming convention
  syscalls: rename struct pt_regs-based sys_*() to __x64_sys_*()
  syscalls/x86: adapt syscall_wrapper.h to the new syscall stub naming
    convention

 Documentation/process/adding-syscalls.rst |   4 +-
 arch/x86/entry/syscalls/syscall_32.tbl    | 720 +++++++++++-----------
 arch/x86/entry/syscalls/syscall_64.tbl    | 710 ++++++++++-----------
 arch/x86/entry/syscalls/syscalltbl.sh     |  14 +-
 arch/x86/entry/vsyscall/vsyscall_64.c     |   6 +-
 arch/x86/include/asm/syscall_wrapper.h    | 156 +++--
 arch/x86/include/asm/syscalls.h           |   2 +-
 include/linux/compat.h                    |  29 +-
 include/linux/syscalls.h                  |  17 +-
 scripts/bloat-o-meter                     |   4 +-
 10 files changed, 858 insertions(+), 804 deletions(-)

-- 
2.17.0