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| author | Andy Lutomirski <luto@kernel.org> | 2016-01-29 02:11:25 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-01-29 11:46:38 +0300 |
| commit | 302f5b260c322696cbeb962a263a4d2d99864aed (patch) | |
| tree | 5220f43391b35c862d52f47c12f1cb5877ac838a /arch/x86/entry/syscall_64.c | |
| parent | cfcbadb49dabb05efa23e1a0f95f3391c0a815bc (diff) | |
| download | linux-302f5b260c322696cbeb962a263a4d2d99864aed.tar.xz | |
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>
Diffstat (limited to 'arch/x86/entry/syscall_64.c')
| -rw-r--r-- | arch/x86/entry/syscall_64.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c index a1d408772ae6..9dbc5abb6162 100644 --- a/arch/x86/entry/syscall_64.c +++ b/arch/x86/entry/syscall_64.c @@ -6,11 +6,14 @@ #include <asm/asm-offsets.h> #include <asm/syscall.h> -#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long) ; +#define __SYSCALL_64_QUAL_(sym) sym +#define __SYSCALL_64_QUAL_ptregs(sym) ptregs_##sym + +#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long __SYSCALL_64_QUAL_##qual(sym)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); #include <asm/syscalls_64.h> #undef __SYSCALL_64 -#define __SYSCALL_64(nr, sym, qual) [nr] = sym, +#define __SYSCALL_64(nr, sym, qual) [nr] = __SYSCALL_64_QUAL_##qual(sym), extern long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); |