From mboxrd@z Thu Jan 1 00:00:00 1970 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 51C5FC0015E for ; Wed, 9 Aug 2023 10:31:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231185AbjHIKbk (ORCPT ); Wed, 9 Aug 2023 06:31:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231210AbjHIKbj (ORCPT ); Wed, 9 Aug 2023 06:31:39 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54C561BDA for ; Wed, 9 Aug 2023 03:31:39 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id 98e67ed59e1d1-267f8f36a3cso3748494a91.2 for ; Wed, 09 Aug 2023 03:31:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1691577099; x=1692181899; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=hrsBW/bweVeFGqbEFObsS1CtKLg/RluEI+jdzyDd8LM=; b=kp02DhCnBxtJNEdhc8TGr3zPEgGJBqMF/pETbjcWuL0nXrjP+kKw0BOzXHRxFwcyAM Vq8Hq5ZfzKbUUdWMo1HU5Fcs0/p6L5bWv0QDn/JdNjf17WFIdtpK+/8ZCMJ/+33eXRRQ 4pxdlIMTwdRerAi8Zu921N0K3QfZVD6rf2Mg8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691577099; x=1692181899; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=hrsBW/bweVeFGqbEFObsS1CtKLg/RluEI+jdzyDd8LM=; b=cGQY3CfbQiTjxFT9kWVWOiWKzXfC68As0RR19bsf0RO/Rpd8JQQngnvGIActJL6wrE gKk5tUCSe1Bc37wAsKYq29DUVEe9wO/HQ5doqe6JNtqdMG77QNvBsAl0nKV4Cu2zpYra m5avj/nfZF8kalXUscdafTgUhG45CAWE8qNKf+tC0cjPDGbovNip5QRdCIC4NpgmCTfx tv+s9WMr2z3DgntCSa1wQgAe1i9kTGD/J0MLecZW6y+mRliPangQRzxKMsYmFO1Pemau xORgGQCLi3zFWbmwYyuAiw/LB++i0OYjso+yqOUKQKt4/hDNsHycfRRrFqWiScchAz/p ayRQ== X-Gm-Message-State: AOJu0YyUUwfO94IPSyjq7la7gcveHJXM3cuHYD3TBJSvniB0QwwNIIho 3kz391RQGRXmMfxYhpnTS+ikIODClfQXIAaGW4YpeA== X-Google-Smtp-Source: AGHT+IELEKsPXhWoxXahSRpjgF0fdoA/3cunXQAk8442EDq6G3fDPOSobQiaBDQ1GIXYmi9D3LoxJGNFpIcwYMYj9mI= X-Received: by 2002:a17:90a:6fc5:b0:268:2f2:cc88 with SMTP id e63-20020a17090a6fc500b0026802f2cc88mr898566pjk.12.1691577098828; Wed, 09 Aug 2023 03:31:38 -0700 (PDT) MIME-Version: 1.0 References: <169139090386.324433.6412259486776991296.stgit@devnote2> <169139096244.324433.7237290521765120297.stgit@devnote2> In-Reply-To: <169139096244.324433.7237290521765120297.stgit@devnote2> From: Florent Revest Date: Wed, 9 Aug 2023 12:31:27 +0200 Message-ID: Subject: Re: [RFC PATCH v2 5/6] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs To: "Masami Hiramatsu (Google)" Cc: Alexei Starovoitov , Steven Rostedt , 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org On Mon, Aug 7, 2023 at 8:49=E2=80=AFAM Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) > > Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs. ftrace_regs* > If the architecture defines its own ftrace_regs, this copies partial > registers to pt_regs and returns it. If not, ftrace_regs is the same as > pt_regs and ftrace_partial_regs() will return ftrace_regs::regs. > > Signed-off-by: Masami Hiramatsu (Google) > --- > arch/arm64/include/asm/ftrace.h | 11 +++++++++++ > include/linux/ftrace.h | 11 +++++++++++ > 2 files changed, 22 insertions(+) > > diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftr= ace.h > index ab158196480c..b108cd6718cf 100644 > --- a/arch/arm64/include/asm/ftrace.h > +++ b/arch/arm64/include/asm/ftrace.h > @@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_r= egs *fregs) > fregs->pc =3D fregs->lr; > } > > +static __always_inline struct pt_regs * > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *reg= s) > +{ > + memcpy(regs->regs, fregs->regs, sizeof(u64) * 10); Are you intentionally copying that tenth value (fregs.direct_tramp) into pt_regs.regs[9] ? This seems wrong and it looks like it will bite us back one day. Isn't it one of these cases where we can simply use sizeof(fregs->regs) ? > + regs->sp =3D fregs->sp; > + regs->pc =3D fregs->pc; > + regs->x[29] =3D fregs->fp; > + regs->x[30] =3D fregs->lr; > + return regs; > +} > + > int ftrace_regs_query_register_offset(const char *name); > > int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec); > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h > index 3fb94a1a2461..7f45654441b7 100644 > --- a/include/linux/ftrace.h > +++ b/include/linux/ftrace.h > @@ -155,6 +155,17 @@ static __always_inline struct pt_regs *ftrace_get_re= gs(struct ftrace_regs *fregs > return arch_ftrace_get_regs(fregs); > } > > +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \ > + defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS) > + > +static __always_inline struct pt_regs * > +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *reg= s) > +{ > + return arch_ftrace_get_regs((struct ftrace_regs *)fregs); > +} I don't think this works. Suppose you are on x86, WITH_ARGS, and with HAVE_PT_REGS_COMPAT_FTRACE_REGS. If you register to ftrace without FTRACE_OPS_FL_SAVE_REGS you will receive a ftrace_regs from the light ftrace pre-trampoline that has a CS register equal to 0 and arch_ftrace_get_regs will return NULL here, which should never happen. Have you tested your series without registering as FTRACE_OPS_FL_SAVE_REGS = ?