scripts/faddr2line: fix error when addr2line output contains discriminator

When addr2line output contains discriminator, the current awk script
cannot parse it.  This patch fixes it by extracting key words using
regex which is more reliable.

  $ scripts/faddr2line vmlinux tlb_flush_mmu_free+0x26
  tlb_flush_mmu_free+0x26/0x50:
  tlb_flush_mmu_free at mm/memory.c:258 (discriminator 3)
  scripts/faddr2line: eval: line 173: unexpected EOF while looking for matching `)'

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 6870c01 ("scripts/faddr2line: show the code context")
Signed-off-by: Changbin Du <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Kate Stewart <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Changbin Du

scripts/faddr2line

@@ -170,7 +170,10 @@ __faddr2line() {
 		echo "$file_lines" | while read -r line
 		do
 			echo $line
-			eval $(echo $line | awk -F "[ :]" '{printf("n1=%d;n2=%d;f=%s",$NF-5, $NF+5, $(NF-1))}')
+			n=$(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'") {printf("%d\t%s\n", NR, $0)}' $f
 		done