From: Denys Vlasenko <dvlas...@redhat.com> This vDSO code only gets used by 64-bit kernel, not 32-bit. In 64-bit kernels, data segment is the same for 32-bit and 64-bit userspace, and SYSRET insn does load %ss with its selector. No need to repeat it by hand. Segment loads are somewhat expensive: tens of cycles.
Signed-off-by: Denys Vlasenko <dvlas...@redhat.com> CC: Linus Torvalds <torva...@linux-foundation.org> CC: Steven Rostedt <rost...@goodmis.org> CC: Ingo Molnar <mi...@kernel.org> CC: Borislav Petkov <b...@alien8.de> CC: "H. Peter Anvin" <h...@zytor.com> CC: Andy Lutomirski <l...@amacapital.net> CC: Oleg Nesterov <o...@redhat.com> CC: Frederic Weisbecker <fweis...@gmail.com> CC: Alexei Starovoitov <a...@plumgrid.com> CC: Will Drewry <w...@chromium.org> CC: Kees Cook <keesc...@chromium.org> CC: x...@kernel.org CC: linux-kernel@vger.kernel.org Message-Id: <1427129240-15543-1-git-send-email-dvlas...@redhat.com> [removed unnecessary comment] Signed-off-by: Andy Lutomirski <l...@kernel.org> --- arch/x86/vdso/vdso32/syscall.S | 2 -- 1 file changed, 2 deletions(-) diff --git a/arch/x86/vdso/vdso32/syscall.S b/arch/x86/vdso/vdso32/syscall.S index 5415b5613d55..6b286bb5251c 100644 --- a/arch/x86/vdso/vdso32/syscall.S +++ b/arch/x86/vdso/vdso32/syscall.S @@ -19,8 +19,6 @@ __kernel_vsyscall: .Lpush_ebp: movl %ecx, %ebp syscall - movl $__USER32_DS, %ecx - movl %ecx, %ss movl %ebp, %ecx popl %ebp .Lpop_ebp: -- 2.3.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/