From nobody Sun Feb 8 18:27:37 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 55C2BC4332F for ; Wed, 8 Nov 2023 14:29:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343981AbjKHO3B (ORCPT ); Wed, 8 Nov 2023 09:29:01 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235399AbjKHO2g (ORCPT ); Wed, 8 Nov 2023 09:28:36 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C3E3213B for ; Wed, 8 Nov 2023 06:28:29 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A424C433C8; Wed, 8 Nov 2023 14:28:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699453709; bh=G3M7rbLjDgrYIoVpHOxqlUDZWOOF6wiqlb0+xA/Zo8s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eBc2p8Oovhos6kzYacPKsTG2cNxhxOf8Zc9rKcUW5GN5AHQLo8RjtjINvAETh0q6G 7L1hdzBjsdJUvpWoFoOqRFMth+slPDl0CKH39BBf7/lrTNEp7Q13ZI/MWjqIH7gv1l 6orjGNmYalsNsgRNFjwA5tGGGGgPHXRAsvATWYc3TOhGgGoh2+mMrpi4cTJRNyfX/L /8f1wRO2HxRUua3LjREkEPer52K25ScmIJJdCxQ8LMhBUNwihl14mMdDIRr02KoM9Z g81tT2GZ9RBIYxEQZNc+Dk8Epnkrb0xZBu2A45FMsu/yBCTFAH/CyHSR/NCAHlj7t/ FquFR4zRAVsCw== From: "Masami Hiramatsu (Google)" To: Alexei Starovoitov , Steven Rostedt , Florent Revest Cc: linux-trace-kernel@vger.kernel.org, LKML , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Mark Rutland , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: [RFC PATCH v2 21/31] x86/ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Date: Wed, 8 Nov 2023 23:28:23 +0900 Message-Id: <169945370304.55307.2480628822573420604.stgit@devnote2> X-Mailer: git-send-email 2.34.1 In-Reply-To: <169945345785.55307.5003201137843449313.stgit@devnote2> References: <169945345785.55307.5003201137843449313.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Support HAVE_FUNCTION_GRAPH_FREGS on x86-64, which saves ftrace_regs on the stack in ftrace_graph return trampoline so that the callbacks can access registers via ftrace_regs APIs. Note that this only recovers 'rax' and 'rdx' registers because other registers are not used anymore and recovered by caller. 'rax' and 'rdx' will be used for passing the return value. Signed-off-by: Masami Hiramatsu (Google) --- Changes in v2: - Save rsp register and drop clearing orig_ax. --- arch/x86/Kconfig | 3 ++- arch/x86/kernel/ftrace_64.S | 36 ++++++++++++++++++++++++++++-------- 2 files changed, 30 insertions(+), 9 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 66bfabae8814..4b4c2f9d67da 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -219,7 +219,8 @@ config X86 select HAVE_FAST_GUP select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD - select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_GRAPH_FREGS if HAVE_DYNAMIC_FTRACE_WITH_ARGS + select HAVE_FUNCTION_GRAPH_RETVAL if !HAVE_DYNAMIC_FTRACE_WITH_ARGS select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE) select HAVE_FUNCTION_TRACER select HAVE_GCC_PLUGINS diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index 945cfa5f7239..029b0e3a0206 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -348,21 +348,41 @@ STACK_FRAME_NON_STANDARD_FP(__fentry__) SYM_CODE_START(return_to_handler) UNWIND_HINT_UNDEFINED ANNOTATE_NOENDBR - subq $24, %rsp + /* + * Save the registers requires for ftrace_regs; + * rax, rcx, rdx, rdi, rsi, r8, r9 and rbp + */ + subq $(FRAME_SIZE), %rsp + movq %rax, RAX(%rsp) + movq %rcx, RCX(%rsp) + movq %rdx, RDX(%rsp) + movq %rsi, RSI(%rsp) + movq %rdi, RDI(%rsp) + movq %r8, R8(%rsp) + movq %r9, R9(%rsp) + movq %rbp, RBP(%rsp) + /* + * orig_ax is not cleared because it is used for indicating the direct + * trampoline in the fentry. + */ + + leaq FRAME_SIZE(%rsp), %rcx + movq %rcx, RSP(%rsp) =20 - /* Save the return values */ - movq %rax, (%rsp) - movq %rdx, 8(%rsp) - movq %rbp, 16(%rsp) movq %rsp, %rdi =20 call ftrace_return_to_handler =20 movq %rax, %rdi - movq 8(%rsp), %rdx - movq (%rsp), %rax =20 - addq $24, %rsp + /* + * Restore only rax and rdx because other registers are not used + * for return value nor callee saved. Caller will reuse/recover it. + */ + movq RDX(%rsp), %rdx + movq RAX(%rsp), %rax + + addq $(FRAME_SIZE), %rsp /* * Jump back to the old return address. This cannot be JMP_NOSPEC rdi * since IBT would demand that contain ENDBR, which simply isn't so for