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| author |   Dominik Brodowski <linux@dominikbrodowski.net> | 2018-03-06 22:18:08 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2018-03-07 07:57:31 +0100 |
| commit | af52201d991624d2d5adce2c123805b3d42a8d4d (patch) | |
| tree | 6fcb0ec95c5ad0c7fff5dd51abb8df12c623dc53 /arch/x86/entry/entry_64_compat.S | |
| parent | x86/syscalls: Use COMPAT_SYSCALL_DEFINEx() macros for x86-only compat syscalls (diff) | |
| download | linux-dev-af52201d991624d2d5adce2c123805b3d42a8d4d.tar.xz linux-dev-af52201d991624d2d5adce2c123805b3d42a8d4d.zip | |
x86/entry: Do not special-case clone(2) in compat entry
With the CPU renaming registers on its own, and all the overhead of the
syscall entry/exit, it is doubtful whether the compiled output of
mov %r8, %rax
mov %rcx, %r8
mov %rax, %rcx
jmpq sys_clone
is measurably slower than the hand-crafted version of
xchg %r8, %rcx
So get rid of this special case.
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@amacapital.net
Cc: viro@zeniv.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/entry/entry_64_compat.S')
| -rw-r--r-- | arch/x86/entry/entry_64_compat.S | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S index e811dd9c5e99..ff61b7bb750b 100644 --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -406,15 +406,3 @@ ENTRY(entry_INT80_compat) TRACE_IRQS_ON jmp swapgs_restore_regs_and_return_to_usermode END(entry_INT80_compat) - -ENTRY(stub32_clone) - /* - * The 32-bit clone ABI is: clone(..., int tls_val, int *child_tidptr). - * The 64-bit clone ABI is: clone(..., int *child_tidptr, int tls_val). - * - * The native 64-bit kernel's sys_clone() implements the latter, - * so we need to swap arguments here before calling it: - */ - xchg %r8, %rcx - jmp sys_clone -ENDPROC(stub32_clone) |