From patchwork Sun Jul 14 08:27:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen N Rao X-Patchwork-Id: 13732614 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6493513E04C; Sun, 14 Jul 2024 08:30:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720945803; cv=none; b=t4NW/PUByf74nADVq++mUpT4cK+KCEIrR9fR0dBQhLTmPqY+Dj2Pq4RwsOU/1ypRfrMSvlMIDaeVW3lB3GxCtld5PUsFqVNclh952PD31T0MQSixWIQZlM/ZMt+7NCYuOaM1kXKoInbPsF6TonfQD/IMH0pEHDZ23UCrkxPpvsQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720945803; c=relaxed/simple; bh=Ioka5XsUMFumHCOKG404RsMEfa4dS57u3guGUJVji54=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WJnQ2RPbDebaIDDgDNNVDJFmTMOGV0cbUFsZue/nalGiB2RX9FPjjxr8Q1R30zVOfOtZTtY6z2ckFMfcFpTtmxi0n5tibNIw1xTVs6HRg56w+/1Jzt0IdJyRQ3bwep7+3KTuqnbAiZMY3Lh7rP83Hk0fpT2oheuHnDHAVcKqASc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Zt2BoB7W; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Zt2BoB7W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41CD9C116B1; Sun, 14 Jul 2024 08:30:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1720945803; bh=Ioka5XsUMFumHCOKG404RsMEfa4dS57u3guGUJVji54=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Zt2BoB7WmSNdxKHJLar2STWNDmvm7TCUzM6Uhx0zZWtC2oKyLQZj4RLu/7TjiNKCH 8TsXwBXRyIE5jymoJIYqlhPkNeNvqB+Fuvr4VVWKSBMsuYYd7w9SRW0Mtl3UiS9+8W i8jEHMIRr0/9kMS9CFJJ1iizH7R+gjGSRLvKueKA/5KJhgjNf3grHiHrwaqPo12H0g 5qeVB6cDApxSZkxmDWLq0iRzJpwKqVX0nvrqtlawp9P1yhZXXWlJ3lfQ/Mh5yLJ0KE jt4pHTN0gjcVmYI58HwrS0IIpkYY9BI0FHVxjVl+qPWO4Euswyvecc6RMG99ocVh0+ Rh9I6z+6YoUhA== From: Naveen N Rao To: , , , linux-kbuild@vger.kernel.org, Cc: Michael Ellerman , Nicholas Piggin , Christophe Leroy , Steven Rostedt , Masami Hiramatsu , Mark Rutland , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Masahiro Yamada , Hari Bathini , Mahesh Salgaonkar , Vishal Chourasia Subject: [RFC PATCH v4 10/17] powerpc/ftrace: Add a postlink script to validate function tracer Date: Sun, 14 Jul 2024 13:57:46 +0530 Message-ID: <6eac5cc2848a08778dc8ebe6477f3b8ad98f7947.1720942106.git.naveen@kernel.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC Function tracer on powerpc can only work with vmlinux having a .text size of up to ~64MB due to powerpc branch instruction having a limited relative branch range of 32MB. Today, this is only detected on kernel boot when ftrace is init'ed. Add a post-link script to check the size of .text so that we can detect this at build time, and break the build if necessary. We add a dependency on !COMPILE_TEST for CONFIG_HAVE_FUNCTION_TRACER so that allyesconfig and other test builds can continue to work without enabling ftrace. Signed-off-by: Naveen N Rao --- arch/powerpc/Kconfig | 2 +- arch/powerpc/Makefile.postlink | 8 ++++++ arch/powerpc/tools/ftrace_check.sh | 45 ++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+), 1 deletion(-) create mode 100755 arch/powerpc/tools/ftrace_check.sh diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index f8891fbe7c16..68f0e7a5576f 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -244,7 +244,7 @@ config PPC select HAVE_FUNCTION_DESCRIPTORS if PPC64_ELF_ABI_V1 select HAVE_FUNCTION_ERROR_INJECTION select HAVE_FUNCTION_GRAPH_TRACER - select HAVE_FUNCTION_TRACER if PPC64 || (PPC32 && CC_IS_GCC) + select HAVE_FUNCTION_TRACER if !COMPILE_TEST && (PPC64 || (PPC32 && CC_IS_GCC)) select HAVE_GCC_PLUGINS if GCC_VERSION >= 50200 # plugin support on gcc <= 5.1 is buggy on PPC select HAVE_GENERIC_VDSO select HAVE_HARDLOCKUP_DETECTOR_ARCH if PPC_BOOK3S_64 && SMP diff --git a/arch/powerpc/Makefile.postlink b/arch/powerpc/Makefile.postlink index ae5a4256b03d..bb601be36173 100644 --- a/arch/powerpc/Makefile.postlink +++ b/arch/powerpc/Makefile.postlink @@ -24,6 +24,9 @@ else $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/relocs_check.sh "$(OBJDUMP)" "$(NM)" "$@" endif +quiet_cmd_ftrace_check = CHKFTRC $@ + cmd_ftrace_check = $(CONFIG_SHELL) $(srctree)/arch/powerpc/tools/ftrace_check.sh "$(NM)" "$@" + # `@true` prevents complaint when there is nothing to be done vmlinux: FORCE @@ -34,6 +37,11 @@ endif ifdef CONFIG_RELOCATABLE $(call if_changed,relocs_check) endif +ifdef CONFIG_FUNCTION_TRACER +ifndef CONFIG_PPC64_ELF_ABI_V1 + $(call cmd,ftrace_check) +endif +endif clean: rm -f .tmp_symbols.txt diff --git a/arch/powerpc/tools/ftrace_check.sh b/arch/powerpc/tools/ftrace_check.sh new file mode 100755 index 000000000000..33f2fd45e54d --- /dev/null +++ b/arch/powerpc/tools/ftrace_check.sh @@ -0,0 +1,45 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0-or-later +# +# This script checks vmlinux to ensure that all functions can call ftrace_caller() either directly, +# or through the stub, ftrace_tramp_text, at the end of kernel text. + +# Error out if any command fails +set -e + +# Allow for verbose output +if [ "$V" = "1" ]; then + set -x +fi + +if [ $# -lt 2 ]; then + echo "$0 [path to nm] [path to vmlinux]" 1>&2 + exit 1 +fi + +# Have Kbuild supply the path to nm so we handle cross compilation. +nm="$1" +vmlinux="$2" + +stext_addr=$($nm "$vmlinux" | grep -e " [TA] _stext$" | cut -d' ' -f1 | tr '[[:lower:]]' '[[:upper:]]') +ftrace_caller_addr=$($nm "$vmlinux" | grep -e " T ftrace_caller$" | cut -d' ' -f1 | tr '[[:lower:]]' '[[:upper:]]') +ftrace_tramp_addr=$($nm "$vmlinux" | grep -e " T ftrace_tramp_text$" | cut -d' ' -f1 | tr '[[:lower:]]' '[[:upper:]]') + +ftrace_caller_offset=$(echo "ibase=16;$ftrace_caller_addr - $stext_addr" | bc) +ftrace_tramp_offset=$(echo "ibase=16;$ftrace_tramp_addr - $ftrace_caller_addr" | bc) +sz_32m=$(printf "%d" 0x2000000) +sz_64m=$(printf "%d" 0x4000000) + +# ftrace_caller - _stext < 32M +if [ $ftrace_caller_offset -ge $sz_32m ]; then + echo "ERROR: ftrace_caller (0x$ftrace_caller_addr) is beyond 32MiB of _stext" 1>&2 + echo "ERROR: consider disabling CONFIG_FUNCTION_TRACER, or reducing the size of kernel text" 1>&2 + exit 1 +fi + +# ftrace_tramp_text - ftrace_caller < 64M +if [ $ftrace_tramp_offset -ge $sz_64m ]; then + echo "ERROR: kernel text extends beyond 64MiB from ftrace_caller" 1>&2 + echo "ERROR: consider disabling CONFIG_FUNCTION_TRACER, or reducing the size of kernel text" 1>&2 + exit 1 +fi