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Commit 4695bafa authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
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faddr2line: Fix overlapping text section failures, the sequel 



[ Upstream commit dcea997beed694cbd8705100ca1a6eb0d886de69 ]

If a function lives in a section other than .text, but .text also exists
in the object, faddr2line may wrongly assume .text.  This can result in
comically wrong output.  For example:

  $ scripts/faddr2line vmlinux.o enter_from_user_mode+0x1c
  enter_from_user_mode+0x1c/0x30:
  find_next_bit at /home/jpoimboe/git/linux/./include/linux/find.h:40
  (inlined by) perf_clear_dirty_counters at /home/jpoimboe/git/linux/arch/x86/events/core.c:2504

Fix it by passing the section name to addr2line, unless the object file
is vmlinux, in which case the symbol table uses absolute addresses.

Fixes: 1d1a0e7c5100 ("scripts/faddr2line: Fix overlapping text section failures")
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/7d25bc1408bd3a750ac26e60d2f2815a5f4a8363.1654130536.git.jpoimboe@kernel.org


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 1b34d6a9

scripts/faddr2line

+34 −11
Original line number Diff line number Diff line
@@ -95,17 +95,25 @@ __faddr2line() { 
	local print_warnings=$4



	local sym_name=${func_addr%+*}

	local offset=${func_addr#*+}

	offset=${offset%/*}

	local func_offset=${func_addr#*+}

	func_offset=${func_offset%/*}

	local user_size=

	local file_type

	local is_vmlinux=0

	[[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}



	if [[ -z $sym_name ]] || [[ -z $offset ]] || [[ $sym_name = $func_addr ]]; then

	if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then

		warn "bad func+offset $func_addr"

		DONE=1

		return

	fi



	# vmlinux uses absolute addresses in the section table rather than

	# section offsets.

	local file_type=$(${READELF} --file-header $objfile |

		${AWK} '$1 == "Type:" { print $2; exit }')

	[[ $file_type = "EXEC" ]] && is_vmlinux=1



	# 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.
@@ -114,9 +122,11 @@ __faddr2line() { 
		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:

		local sec_size=$(${READELF} --section-headers --wide $objfile |

		sec_size=$(${READELF} --section-headers --wide $objfile |

			sed 's/\[ /\[/' |

			${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')
@@ -126,6 +136,17 @@ __faddr2line() { 
			return

		fi



		# Get the section name:

		sec_name=$(${READELF} --section-headers --wide $objfile |

			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
@@ -174,10 +195,10 @@ __faddr2line() { 


		sym_size=0x$(printf %x $sym_size)



		# Calculate the section address from user-supplied offset:

		local addr=$(($sym_addr + $offset))

		# Calculate the address from user-supplied offset:

		local addr=$(($sym_addr + $func_offset))

		if [[ -z $addr ]] || [[ $addr = 0 ]]; then

			warn "bad address: $sym_addr + $offset"

			warn "bad address: $sym_addr + $func_offset"

			DONE=1

			return

		fi
@@ -191,9 +212,9 @@ __faddr2line() { 
		fi



		# Make sure the provided offset is within the symbol's range:

		if [[ $offset -gt $sym_size ]]; then

		if [[ $func_offset -gt $sym_size ]]; then

			[[ $print_warnings = 1 ]] &&

				echo "skipping $sym_name address at $addr due to size mismatch ($offset > $sym_size)"

				echo "skipping $sym_name address at $addr due to size mismatch ($func_offset > $sym_size)"

			continue

		fi
@@ -202,11 +223,13 @@ __faddr2line() { 
		[[ $FIRST = 0 ]] && echo

		FIRST=0



		echo "$sym_name+$offset/$sym_size:"

		echo "$sym_name+$func_offset/$sym_size:"



		# Pass section address to addr2line and strip absolute paths

		# from the output:

		local output=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")

		local args="--functions --pretty-print --inlines --exe=$objfile"

		[[ $is_vmlinux = 0 ]] && args="$args --section=$sec_name"

		local output=$(${ADDR2LINE} $args $addr | sed "s; $dir_prefix\(\./\)*; ;")

		[[ -z $output ]] && continue



		# Default output (non --list):