linux/arch/x86
Andy Lutomirski 302f5b260c x86/entry/64: Always run ptregs-using syscalls on the slow path
64-bit syscalls currently have an optimization in which they are
called with partial pt_regs.  A small handful require full
pt_regs.

In the 32-bit and compat cases, I cleaned this up by forcing
full pt_regs for all syscalls.  The performance hit doesn't
really matter as the affected system calls are fundamentally
heavy and this is the 32-bit compat case.

I want to clean up the 64-bit case as well, but I don't want to
hurt fast path performance.  To do that, I want to force the
syscalls that use pt_regs onto the slow path.  This will enable
us to make slow path syscalls be real ABI-compliant C functions.

Use the new syscall entry qualification machinery for this.
'stub_clone' is now 'stub_clone/ptregs'.

The next patch will eliminate the stubs, and we'll just have
'sys_clone/ptregs'.

As of this patch, two-phase entry tracing is no longer used.  It
has served its purpose (namely a huge speedup on some workloads
prior to more general opportunistic SYSRET support), and once
the dust settles I'll send patches to back it out.

The implementation is heavily based on a patch from Brian Gerst:

  http://lkml.kernel.org/g/1449666173-15366-1-git-send-email-brgerst@gmail.com

Originally-From: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b9beda88460bcefec6e7d792bd44eca9b760b0c4.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-29 09:46:38 +01:00
..
boot UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
configs Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-09-04 15:49:32 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-01-12 18:51:14 -08:00
entry x86/entry/64: Always run ptregs-using syscalls on the slow path 2016-01-29 09:46:38 +01:00
ia32 Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
include Linux 4.5-rc1 2016-01-29 09:41:18 +01:00
kernel x86/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
kvm kvm: rename pfn_t to kvm_pfn_t 2016-01-15 17:56:32 -08:00
lguest Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 16:26:03 -08:00
lib Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-01-11 16:46:20 -08:00
math-emu Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
mm mm, x86: get_user_pages() for dax mappings 2016-01-15 17:56:32 -08:00
net bpf, x86: detect/optimize loading 0 immediates 2015-12-18 16:04:51 -05:00
oprofile
pci PCI changes for the v4.5 merge window: 2016-01-21 11:52:16 -08:00
platform Power management and ACPI updates for v4.5-rc1 2016-01-12 20:25:09 -08:00
power x86/pm: Introduce quirk framework to save/restore extra MSR registers around suspend/resume 2015-11-26 10:04:53 +01:00
purgatory
ras x86/ras/mce_amd_inj: Inject bank 4 errors on the NBC 2015-10-12 16:15:48 +02:00
realmode UBSAN: run-time undefined behavior sanity checker 2016-01-20 17:09:18 -08:00
tools
um x86/syscalls: Add syscall entry qualifiers 2016-01-29 09:46:38 +01:00
video
xen xen: features and fixes for 4.5-rc0 2016-01-12 13:05:36 -08:00
.gitignore
Kbuild
Kconfig Merge branch 'akpm' (patches from Andrew) 2016-01-21 12:32:08 -08:00
Kconfig.cpu x86/Kconfig/cpus: Fix/complete CPU type help texts 2015-10-21 11:12:56 +02:00
Kconfig.debug libnvdimm for 4.5 2016-01-13 19:15:14 -08:00
Makefile Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2015-11-04 09:11:12 -08:00
Makefile_32.cpu
Makefile.um