From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756651AbbAHQ0E (ORCPT ); Thu, 8 Jan 2015 11:26:04 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58569 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756519AbbAHQ0B (ORCPT ); Thu, 8 Jan 2015 11:26:01 -0500 From: Denys Vlasenko To: linux-kernel@vger.kernel.org Cc: Denys Vlasenko , Linus Torvalds , Oleg Nesterov , "H. Peter Anvin" , Andy Lutomirski , Frederic Weisbecker , X86 ML , Alexei Starovoitov , Will Drewry , Kees Cook Subject: [PATCH 3/4] x86: open-code register save/restore in trace_hardirqs thunks Date: Thu, 8 Jan 2015 17:25:14 +0100 Message-Id: <1420734315-30943-4-git-send-email-dvlasenk@redhat.com> In-Reply-To: <1420734315-30943-1-git-send-email-dvlasenk@redhat.com> References: <1420734315-30943-1-git-send-email-dvlasenk@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a preparatory patch for change in "struct pt_regs" handling in entry_64.S. trace_hardirqs thunks were (ab)using a part of pt_regs handling code, namely SAVE_ARGS/RESTORE_ARGS macros, to save/restore registers across C function calls. Since SAVE_ARGS is going to be changed, open-code register saving/restoring here. Incidentally, this removes a bit of dead code: one SAVE_ARGS was used just to emit a CFI annotation, but it also generated unreachable assembly insns. Signed-off-by: Denys Vlasenko CC: Linus Torvalds CC: Oleg Nesterov CC: "H. Peter Anvin" CC: Andy Lutomirski CC: Frederic Weisbecker CC: X86 ML CC: Alexei Starovoitov CC: Will Drewry CC: Kees Cook CC: linux-kernel@vger.kernel.org --- arch/x86/lib/thunk_64.S | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S index b30b5eb..03a3883 100644 --- a/arch/x86/lib/thunk_64.S +++ b/arch/x86/lib/thunk_64.S @@ -16,10 +16,20 @@ \name: CFI_STARTPROC - /* this one pushes 9 elems, the next one would be %rIP */ - SAVE_ARGS + subq $9*8, %rsp + CFI_ADJUST_CFA_OFFSET 9*8 + movq_cfi r11, 0*8 + movq_cfi r10, 1*8 + movq_cfi r9, 2*8 + movq_cfi r8, 3*8 + movq_cfi rax, 4*8 + movq_cfi rcx, 5*8 + movq_cfi rdx, 6*8 + movq_cfi rsi, 7*8 + movq_cfi rdi, 8*8 .if \put_ret_addr_in_rdi + /* 9*8(%rsp) is return addr on stack */ movq_cfi_restore 9*8, rdi .endif @@ -45,11 +55,20 @@ #endif #endif - /* SAVE_ARGS below is used only for the .cfi directives it contains. */ CFI_STARTPROC - SAVE_ARGS + CFI_ADJUST_CFA_OFFSET 9*8 restore: - RESTORE_ARGS + movq_cfi_restore 0*8, r11 + movq_cfi_restore 1*8, r10 + movq_cfi_restore 2*8, r9 + movq_cfi_restore 3*8, r8 + movq_cfi_restore 4*8, rax + movq_cfi_restore 5*8, rcx + movq_cfi_restore 6*8, rdx + movq_cfi_restore 7*8, rsi + movq_cfi_restore 8*8, rdi + addq 9*8, %rsp + CFI_ADJUST_CFA_OFFSET -9*8 ret CFI_ENDPROC _ASM_NOKPROBE(restore) -- 1.8.1.4