Subject: profiling is broken for larger programs (+fix)
Index:	lib/libc/pdp/csu/mon.c 2.11BSD

Description:
	Profiling is broken for programs with text segments larger than
	32kb.

Repeat-By:
	Compile a program which has more than 32kb of text ('fsck' is a good 
	choice) with the -p option.  Run the program and observe the core dump.

Fix:
	Apply the patch below, compile and reinstall /lib/mcrt0.o
	The Makefile is also updated, it was lacking a CFLAGS statement
	to use when compiling the mon.c module.

	The problem was a negative increment to sbrk() was being
	calculated when the text size was greater than 32kb.  This
	released part of the program's .bss segment back to the system
	causing a segmentation violation when mcount: was called the
	first time.
	
---------------------------------------------------------------------
*** /usr/src/lib/libc/pdp/csu/mon.c.old	Thu May  7 19:56:56 1987
--- /usr/src/lib/libc/pdp/csu/mon.c	Mon Mar 30 16:01:22 1992
***************
*** 5,11 ****
   */
  
  #if defined(LIBC_SCCS) && !defined(lint)
! static char sccsid[] = "@(#)mon.c	5.4 (Berkeley) 5/3/87";
  #endif LIBC_SCCS and not lint
  
  #define ARCDENSITY	1	/* density of routines per 100 bytes */
--- 5,11 ----
   */
  
  #if defined(LIBC_SCCS) && !defined(lint)
! static char sccsid[] = "@(#)mon.c	5.5 (GTE) 3/23/92";
  #endif LIBC_SCCS and not lint
  
  #define ARCDENSITY	1	/* density of routines per 100 bytes */
***************
*** 38,52 ****
  	char *lowpc;
  	char *highpc;
  {
! 	int cntsize, monsize;
  	char *buffer;
  	extern char *sbrk();
  	extern char *minbrk;
  
! 	cntsize = (highpc - lowpc) * ARCDENSITY / 100;
  	if (cntsize < MINARCS)
  		cntsize = MINARCS;
! 	monsize = (highpc - lowpc + HISTFRACTION - 1) / HISTFRACTION
  		+ sizeof(struct phdr) + cntsize * sizeof(struct cnt);
  	monsize = (monsize + 1) & ~1;
  	buffer = sbrk(monsize);
--- 38,52 ----
  	char *lowpc;
  	char *highpc;
  {
! 	unsigned int cntsize, monsize;
  	char *buffer;
  	extern char *sbrk();
  	extern char *minbrk;
  
! 	cntsize = (unsigned)(highpc - lowpc) * ARCDENSITY / 100;
  	if (cntsize < MINARCS)
  		cntsize = MINARCS;
! 	monsize = (unsigned)(highpc - lowpc + HISTFRACTION - 1) / HISTFRACTION
  		+ sizeof(struct phdr) + cntsize * sizeof(struct cnt);
  	monsize = (monsize + 1) & ~1;
  	buffer = sbrk(monsize);
*** /usr/src/lib/libc/pdp/csu/Makefile.old	Fri Aug  3 12:13:37 1990
--- /usr/src/lib/libc/pdp/csu/Makefile	Mon Mar 30 17:11:45 1992
***************
*** 13,18 ****
--- 13,19 ----
  SRCS=	crt0.s mon.c mcount.s gmon.c
  #OBJS=	crt0.o mcrt0.o gcrt0.o mon.o gmon.o
  OBJS=	crt0.o mcrt0.o mon.o
+ CFLAGS=	-O ${DEFS}
  TAGSFILE=tags
  
  all: ${OBJS}
***************
*** 41,47 ****
  	ld -x -r -o mcrt0.o moncrt0.o mon.o
  
  mon.o: mon.c mcount.s mon.ex
! 	cc -S ${DEFS} ${DFLAGS} mon.c
  	ex - mon.s < mon.ex
  	cat mon.s mcount.s > x.s
  	/lib/cpp ${DEFS} ${DFLAGS} x.s | sed 's;^#;/;' > xx.s
--- 42,48 ----
  	ld -x -r -o mcrt0.o moncrt0.o mon.o
  
  mon.o: mon.c mcount.s mon.ex
! 	cc ${CFLAGS} -S ${DFLAGS} mon.c
  	ex - mon.s < mon.ex
  	cat mon.s mcount.s > x.s
  	/lib/cpp ${DEFS} ${DFLAGS} x.s | sed 's;^#;/;' > xx.s
***************
*** 50,56 ****
  	rm -f x.o x.s xx.s mon.s
  
  gmon.o: gmon.c gmon.h gmon.ex
! 	cc -S ${DEFS} ${DFLAGS} gmon.c
  	ex - gmon.s < gmon.ex
  	as -o x.o gmon.s
  	ld -x -r -o gmon.o x.o
--- 51,57 ----
  	rm -f x.o x.s xx.s mon.s
  
  gmon.o: gmon.c gmon.h gmon.ex
! 	cc ${CFLAGS} -S ${DFLAGS} gmon.c
  	ex - gmon.s < gmon.ex
  	as -o x.o gmon.s
  	ld -x -r -o gmon.o x.o