Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 380 insertions, 0 deletions

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] <object file> <func+offset> <func+offset>..." >&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