From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- scripts/faddr2line | 380 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 380 insertions(+) create mode 100755 scripts/faddr2line (limited to 'scripts/faddr2line') diff --git a/scripts/faddr2line b/scripts/faddr2line new file mode 100755 index 000000000..622875396 --- /dev/null +++ b/scripts/faddr2line @@ -0,0 +1,380 @@ +#!/usr/bin/env bash +# SPDX-License-Identifier: GPL-2.0 +# +# Translate stack dump function offsets. +# +# addr2line doesn't work with KASLR addresses. This works similarly to +# addr2line, but instead takes the 'func+0x123' format as input: +# +# $ ./scripts/faddr2line ~/k/vmlinux meminfo_proc_show+0x5/0x568 +# meminfo_proc_show+0x5/0x568: +# meminfo_proc_show at fs/proc/meminfo.c:27 +# +# If the address is part of an inlined function, the full inline call chain is +# printed: +# +# $ ./scripts/faddr2line ~/k/vmlinux native_write_msr+0x6/0x27 +# native_write_msr+0x6/0x27: +# arch_static_branch at arch/x86/include/asm/msr.h:121 +# (inlined by) static_key_false at include/linux/jump_label.h:125 +# (inlined by) native_write_msr at arch/x86/include/asm/msr.h:125 +# +# The function size after the '/' in the input is optional, but recommended. +# It's used to help disambiguate any duplicate symbol names, which can occur +# rarely. If the size is omitted for a duplicate symbol then it's possible for +# multiple code sites to be printed: +# +# $ ./scripts/faddr2line ~/k/vmlinux raw_ioctl+0x5 +# raw_ioctl+0x5/0x20: +# raw_ioctl at drivers/char/raw.c:122 +# +# raw_ioctl+0x5/0xb1: +# raw_ioctl at net/ipv4/raw.c:876 +# +# Multiple addresses can be specified on a single command line: +# +# $ ./scripts/faddr2line ~/k/vmlinux type_show+0x10/45 free_reserved_area+0x90 +# type_show+0x10/0x2d: +# type_show at drivers/video/backlight/backlight.c:213 +# +# free_reserved_area+0x90/0x123: +# free_reserved_area at mm/page_alloc.c:6429 (discriminator 2) + + +set -o errexit +set -o nounset + +usage() { + echo "usage: faddr2line [--list] ..." >&2 + exit 1 +} + +warn() { + echo "$1" >&2 +} + +die() { + echo "ERROR: $1" >&2 + exit 1 +} + +UTIL_SUFFIX="" +if [[ "${LLVM:-}" == "" ]]; then + UTIL_PREFIX=${CROSS_COMPILE:-} +else + UTIL_PREFIX=llvm- + + if [[ "${LLVM}" == *"/" ]]; then + UTIL_PREFIX=${LLVM}${UTIL_PREFIX} + elif [[ "${LLVM}" == "-"* ]]; then + UTIL_SUFFIX=${LLVM} + fi +fi + +READELF="${UTIL_PREFIX}readelf${UTIL_SUFFIX}" +ADDR2LINE="${UTIL_PREFIX}addr2line${UTIL_SUFFIX}" +AWK="awk" +GREP="grep" + +# Enforce ASCII-only output from tools like readelf +# ensuring sed processes strings correctly. +export LANG=C + +command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed" +command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed" +command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed" + +# Try to figure out the source directory prefix so we can remove it from the +# addr2line output. HACK ALERT: This assumes that start_kernel() is in +# init/main.c! This only works for vmlinux. Otherwise it falls back to +# printing the absolute path. +find_dir_prefix() { + local start_kernel_addr=$(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | + ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}') + [[ -z $start_kernel_addr ]] && return + + run_addr2line ${start_kernel_addr} "" + [[ -z $ADDR2LINE_OUT ]] && return + + local file_line=${ADDR2LINE_OUT#* at } + if [[ -z $file_line ]] || [[ $file_line = $ADDR2LINE_OUT ]]; then + return + fi + local prefix=${file_line%init/main.c:*} + if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then + return + fi + + DIR_PREFIX=$prefix + return 0 +} + +run_readelf() { + local objfile=$1 + local tmpfile + tmpfile=$(mktemp) + + ${READELF} --file-header --section-headers --symbols --wide "$objfile" > "$tmpfile" + + # This assumes that readelf first prints the file header, then the section headers, then the symbols. + # Note: It seems that GNU readelf does not prefix section headers with the "There are X section headers" + # line when multiple options are given, so let's also match with the "Section Headers:" line. + ELF_FILEHEADER=$(sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/q;p' "$tmpfile") + ELF_SECHEADERS=$(sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/,$p' "$tmpfile" | sed -n '/Symbol table .* contains [0-9]* entries:/q;p') + ELF_SYMS=$(sed -n '/Symbol table .* contains [0-9]* entries:/,$p' "$tmpfile") + + rm -f -- "$tmpfile" +} + +check_vmlinux() { + # vmlinux uses absolute addresses in the section table rather than + # section offsets. + IS_VMLINUX=0 + local file_type=$(echo "${ELF_FILEHEADER}" | + ${AWK} '$1 == "Type:" { print $2; exit }') + if [[ $file_type = "EXEC" ]] || [[ $file_type == "DYN" ]]; then + IS_VMLINUX=1 + fi +} + +init_addr2line() { + local objfile=$1 + + check_vmlinux + + ADDR2LINE_ARGS="--functions --pretty-print --inlines --addresses --exe=$objfile" + if [[ $IS_VMLINUX = 1 ]]; then + # If the executable file is vmlinux, we don't pass section names to + # addr2line, so we can launch it now as a single long-running process. + coproc ADDR2LINE_PROC (${ADDR2LINE} ${ADDR2LINE_ARGS}) + fi +} + +run_addr2line() { + local addr=$1 + local sec_name=$2 + + if [[ $IS_VMLINUX = 1 ]]; then + # We send to the addr2line process: (1) the address, then (2) a sentinel + # value, i.e., something that can't be interpreted as a valid address + # (i.e., ","). This causes addr2line to write out: (1) the answer for + # our address, then (2) either "?? ??:0" or "0x0...0: ..." (if + # using binutils' addr2line), or "," (if using LLVM's addr2line). + echo ${addr} >& "${ADDR2LINE_PROC[1]}" + echo "," >& "${ADDR2LINE_PROC[1]}" + local first_line + read -r first_line <& "${ADDR2LINE_PROC[0]}" + ADDR2LINE_OUT=$(echo "${first_line}" | sed 's/^0x[0-9a-fA-F]*: //') + while read -r line <& "${ADDR2LINE_PROC[0]}"; do + if [[ "$line" == "?? ??:0" ]] || [[ "$line" == "," ]] || [[ $(echo "$line" | ${GREP} "^0x00*: ") ]]; then + break + fi + ADDR2LINE_OUT+=$'\n'$(echo "$line" | sed 's/^0x[0-9a-fA-F]*: //') + done + else + # Run addr2line as a single invocation. + local sec_arg + [[ -z $sec_name ]] && sec_arg="" || sec_arg="--section=${sec_name}" + ADDR2LINE_OUT=$(${ADDR2LINE} ${ADDR2LINE_ARGS} ${sec_arg} ${addr} | sed 's/^0x[0-9a-fA-F]*: //') + fi +} + +__faddr2line() { + local objfile=$1 + local func_addr=$2 + local dir_prefix=$3 + local print_warnings=$4 + + local sym_name=${func_addr%+*} + local func_offset=${func_addr#*+} + func_offset=${func_offset%/*} + local user_size= + [[ $func_addr =~ "/" ]] && user_size=${func_addr#*/} + + if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then + warn "bad func+offset $func_addr" + DONE=1 + return + fi + + # Go through each of the object's symbols which match the func name. + # In rare cases there might be duplicates, in which case we print all + # matches. + while read line; do + local fields=($line) + local sym_addr=0x${fields[1]} + local sym_elf_size=${fields[2]} + local sym_sec=${fields[6]} + local sec_size + local sec_name + + # Get the section size: + sec_size=$(echo "${ELF_SECHEADERS}" | sed 's/\[ /\[/' | + ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }') + + if [[ -z $sec_size ]]; then + warn "bad section size: section: $sym_sec" + DONE=1 + return + fi + + # Get the section name: + sec_name=$(echo "${ELF_SECHEADERS}" | sed 's/\[ /\[/' | + ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print $2; exit }') + + if [[ -z $sec_name ]]; then + warn "bad section name: section: $sym_sec" + DONE=1 + return + fi + + # Calculate the symbol size. + # + # Unfortunately we can't use the ELF size, because kallsyms + # also includes the padding bytes in its size calculation. For + # kallsyms, the size calculation is the distance between the + # symbol and the next symbol in a sorted list. + local sym_size + local cur_sym_addr + local found=0 + while read line; do + local fields=($line) + cur_sym_addr=0x${fields[1]} + local cur_sym_elf_size=${fields[2]} + local cur_sym_name=${fields[7]:-} + + # is_mapping_symbol(cur_sym_name) + if [[ ${cur_sym_name} =~ ^(\.L|L0|\$) ]]; then + continue + fi + + if [[ $cur_sym_addr = $sym_addr ]] && + [[ $cur_sym_elf_size = $sym_elf_size ]] && + [[ $cur_sym_name = $sym_name ]]; then + found=1 + continue + fi + + if [[ $found = 1 ]]; then + sym_size=$(($cur_sym_addr - $sym_addr)) + [[ $sym_size -lt $sym_elf_size ]] && continue; + found=2 + break + fi + done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2) + + if [[ $found = 0 ]]; then + warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size" + DONE=1 + return + fi + + # If nothing was found after the symbol, assume it's the last + # symbol in the section. + [[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr)) + + if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then + warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr" + DONE=1 + return + fi + + sym_size=0x$(printf %x $sym_size) + + # Calculate the address from user-supplied offset: + local addr=$(($sym_addr + $func_offset)) + if [[ -z $addr ]] || [[ $addr = 0 ]]; then + warn "bad address: $sym_addr + $func_offset" + DONE=1 + return + fi + addr=0x$(printf %x $addr) + + # If the user provided a size, make sure it matches the symbol's size: + if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then + [[ $print_warnings = 1 ]] && + echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)" + continue; + fi + + # Make sure the provided offset is within the symbol's range: + if [[ $func_offset -gt $sym_size ]]; then + [[ $print_warnings = 1 ]] && + echo "skipping $sym_name address at $addr due to size mismatch ($func_offset > $sym_size)" + continue + fi + + # In case of duplicates or multiple addresses specified on the + # cmdline, separate multiple entries with a blank line: + [[ $FIRST = 0 ]] && echo + FIRST=0 + + echo "$sym_name+$func_offset/$sym_size:" + + # Pass section address to addr2line and strip absolute paths + # from the output: + run_addr2line $addr $sec_name + local output=$(echo "${ADDR2LINE_OUT}" | sed "s; $dir_prefix\(\./\)*; ;") + [[ -z $output ]] && continue + + # Default output (non --list): + if [[ $LIST = 0 ]]; then + echo "$output" | while read -r line + do + echo $line + done + DONE=1; + continue + fi + + # For --list, show each line with its corresponding source code: + echo "$output" | while read -r line + do + echo + echo $line + n=$(echo $line | sed 's/.*:\([0-9]\+\).*/\1/g') + n1=$[$n-5] + n2=$[$n+5] + f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g') + ${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f + done + + DONE=1 + + done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$8 == fn') +} + +[[ $# -lt 2 ]] && usage + +objfile=$1 + +LIST=0 +[[ "$objfile" == "--list" ]] && LIST=1 && shift && objfile=$1 + +[[ ! -f $objfile ]] && die "can't find objfile $objfile" +shift + +run_readelf $objfile + +echo "${ELF_SECHEADERS}" | ${GREP} -q '\.debug_info' || die "CONFIG_DEBUG_INFO not enabled" + +init_addr2line $objfile + +DIR_PREFIX=supercalifragilisticexpialidocious +find_dir_prefix + +FIRST=1 +while [[ $# -gt 0 ]]; do + func_addr=$1 + shift + + # print any matches found + DONE=0 + __faddr2line $objfile $func_addr $DIR_PREFIX 0 + + # if no match was found, print warnings + if [[ $DONE = 0 ]]; then + __faddr2line $objfile $func_addr $DIR_PREFIX 1 + warn "no match for $func_addr" + fi +done -- cgit v1.3.1