From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- scripts/bootgraph.pl | 224 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 224 insertions(+) create mode 100755 scripts/bootgraph.pl (limited to 'scripts/bootgraph.pl') diff --git a/scripts/bootgraph.pl b/scripts/bootgraph.pl new file mode 100755 index 000000000..79c903292 --- /dev/null +++ b/scripts/bootgraph.pl @@ -0,0 +1,224 @@ +#!/usr/bin/env perl +# SPDX-License-Identifier: GPL-2.0-only + +# Copyright 2008, Intel Corporation +# +# This file is part of the Linux kernel +# +# Authors: +# Arjan van de Ven + + +# +# This script turns a dmesg output into a SVG graphic that shows which +# functions take how much time. You can view SVG graphics with various +# programs, including Inkscape, The Gimp and Firefox. +# +# +# For this script to work, the kernel needs to be compiled with the +# CONFIG_PRINTK_TIME configuration option enabled, and with +# "initcall_debug" passed on the kernel command line. +# +# usage: +# dmesg | perl scripts/bootgraph.pl > output.svg +# + +use strict; +use Getopt::Long; +my $header = 0; + +sub help { + my $text = << "EOM"; +Usage: +1) dmesg | perl scripts/bootgraph.pl [OPTION] > output.svg +2) perl scripts/bootgraph.pl -h + +Options: + -header Insert kernel version and date +EOM + my $std=shift; + if ($std == 1) { + print STDERR $text; + } else { + print $text; + } + exit; +} + +GetOptions( + 'h|help' =>\&help, + 'header' =>\$header +); + +my %start; +my %end; +my %type; +my $done = 0; +my $maxtime = 0; +my $firsttime = 99999; +my $count = 0; +my %pids; +my %pidctr; + +my $headerstep = 20; +my $xheader = 15; +my $yheader = 25; +my $cyheader = 0; + +while (<>) { + my $line = $_; + if ($line =~ /([0-9\.]+)\] calling ([a-zA-Z0-9\_\.]+)\+/) { + my $func = $2; + if ($done == 0) { + $start{$func} = $1; + $type{$func} = 0; + if ($1 < $firsttime) { + $firsttime = $1; + } + } + if ($line =~ /\@ ([0-9]+)/) { + $pids{$func} = $1; + } + $count = $count + 1; + } + + if ($line =~ /([0-9\.]+)\] async_waiting @ ([0-9]+)/) { + my $pid = $2; + my $func; + if (!defined($pidctr{$pid})) { + $func = "wait_" . $pid . "_1"; + $pidctr{$pid} = 1; + } else { + $pidctr{$pid} = $pidctr{$pid} + 1; + $func = "wait_" . $pid . "_" . $pidctr{$pid}; + } + if ($done == 0) { + $start{$func} = $1; + $type{$func} = 1; + if ($1 < $firsttime) { + $firsttime = $1; + } + } + $pids{$func} = $pid; + $count = $count + 1; + } + + if ($line =~ /([0-9\.]+)\] initcall ([a-zA-Z0-9\_\.]+)\+.*returned/) { + if ($done == 0) { + $end{$2} = $1; + $maxtime = $1; + } + } + + if ($line =~ /([0-9\.]+)\] async_continuing @ ([0-9]+)/) { + my $pid = $2; + my $func = "wait_" . $pid . "_" . $pidctr{$pid}; + $end{$func} = $1; + $maxtime = $1; + } + if ($line =~ /Write protecting the/) { + $done = 1; + } + if ($line =~ /Freeing unused kernel memory/) { + $done = 1; + } +} + +if ($count == 0) { + print STDERR < \n"; +print "\n"; + + +if ($header) { + my $version = `uname -a`; + my $date = `date`; + print "Kernel version: $version\n"; + $cyheader = $yheader+$headerstep; + print "Date: $date\n"; +} + +my @styles; + +$styles[0] = "fill:rgb(0,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[1] = "fill:rgb(0,255,0);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[2] = "fill:rgb(255,0,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[3] = "fill:rgb(255,255,20);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[4] = "fill:rgb(255,0,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[5] = "fill:rgb(0,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[6] = "fill:rgb(0,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[7] = "fill:rgb(0,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[8] = "fill:rgb(255,0,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[9] = "fill:rgb(255,255,128);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[10] = "fill:rgb(255,128,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; +$styles[11] = "fill:rgb(128,255,255);fill-opacity:0.5;stroke-width:1;stroke:rgb(0,0,0)"; + +my $style_wait = "fill:rgb(128,128,128);fill-opacity:0.5;stroke-width:0;stroke:rgb(0,0,0)"; + +my $mult = 1950.0 / ($maxtime - $firsttime); +my $threshold2 = ($maxtime - $firsttime) / 120.0; +my $threshold = $threshold2/10; +my $stylecounter = 0; +my %rows; +my $rowscount = 1; +my @initcalls = sort { $start{$a} <=> $start{$b} } keys(%start); + +foreach my $key (@initcalls) { + my $duration = $end{$key} - $start{$key}; + + if ($duration >= $threshold) { + my ($s, $s2, $s3, $e, $w, $y, $y2, $style); + my $pid = $pids{$key}; + + if (!defined($rows{$pid})) { + $rows{$pid} = $rowscount; + $rowscount = $rowscount + 1; + } + $s = ($start{$key} - $firsttime) * $mult; + $s2 = $s + 6; + $s3 = $s + 1; + $e = ($end{$key} - $firsttime) * $mult; + $w = $e - $s; + + $y = $rows{$pid} * 150; + $y2 = $y + 4; + + $style = $styles[$stylecounter]; + $stylecounter = $stylecounter + 1; + if ($stylecounter > 11) { + $stylecounter = 0; + }; + + if ($type{$key} == 1) { + $y = $y + 15; + print "\n"; + } else { + print "\n"; + if ($duration >= $threshold2) { + print "$key\n"; + } else { + print "$key\n"; + } + } + } +} + + +# print the time line on top +my $time = $firsttime; +my $step = ($maxtime - $firsttime) / 15; +while ($time < $maxtime) { + my $s3 = ($time - $firsttime) * $mult; + my $tm = int($time * 100) / 100.0; + print "$tm\n"; + $time = $time + $step; +} + +print "\n"; -- cgit v1.3.1