Handle kernel load addresses better.
 [jmk] --rw-rw-r-- M 1428987 glenda sys 2085 Jan 28 12:56 sys/src/libmach/2.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/2.c:76,82 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/2.c:76,82
	  	0,		/* value */
	  	0x2000,		/* page size */
	  	0x80000000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0x80000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	2,		/* quantization of pc */
	  	4,		/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 glenda sys 1564 Jan 28 12:56 sys/src/libmach/5.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/5.c:54,60 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/5.c:54,60
	  	0,		/* static base register value */
	  	0x1000,		/* page size */
	  	0xC0000000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0xC0000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	4,		/* quantization of pc */
	  	4,		/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 jmk sys 3482 Jan 28 12:56 sys/src/libmach/6.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/6.c:107,113 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/6.c:107,113
	  	0,			/* static base register value */
	  	0x1000,			/* page size */
	  	0xFFFFFFFF80110000ULL,	/* kernel base */
	- 	0,			/* kernel text mask */
	+ 	0xFFFF800000000000ULL,	/* kernel text mask */
	  	0x00007FFFFFFFF000ULL,	/* user stack top */
	  	1,			/* quantization of pc */
	  	8,			/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 glenda sys 3310 Jan 28 12:57 sys/src/libmach/7.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/7.c:104,110 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/7.c:104,110
	  	0,		/* static base register value */
	  	0x2000,		/* page size */
	  	0x80000000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0xF0000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	4,		/* quantization of pc */
	  	4,		/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 glenda sys 2071 Jan 28 12:57 sys/src/libmach/8.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/8.c:69,75 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/8.c:69,75
	  	0,		/* static base register value */
	  	0x1000,		/* page size */
	  	0x80100000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0xF0000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	1,		/* quantization of pc */
	  	4,		/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 glenda sys 16006 Jan 28 12:56 sys/src/libmach/executable.c
	[diffs elided - too long]
	[diff -c /n/sourcesdump/2006/0128/plan9/sys/src/libmach/executable.c /n/sourcesdump/2006/0129/plan9/sys/src/libmach/executable.c]
 [jmk] --rw-rw-r-- M 1428987 glenda sys 3381 Jan 28 12:57 sys/src/libmach/k.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/k.c:108,114 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/k.c:108,114
	  	0,		/* value */
	  	0x1000,		/* page size */
	  	0xE0000000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0xE0000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	4,		/* quantization of pc */
	  	4,		/* szaddr */
 [jmk] --rw-rw-r-- M 1428987 glenda sys 26745 Jan 28 12:56 sys/src/libmach/sym.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/sym.c:103,109 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/sym.c:103,109
	  	nsym = 0;
	  	size = 0;
	  	for(p = symbols; size < fp->symsz; p++, nsym++) {
	- 		if(fp->magic & HDR_MAGIC){
	+ 		if(fp->_magic && (fp->magic & HDR_MAGIC)){
	  			svalsz = 8;
	  			if(Bread(&b, &vl, 8) != 8)
	  				return symerrmsg(8, "symbol");
 [jmk] --rw-rw-r-- M 1428987 jmk sys 3447 Jan 28 12:56 sys/src/libmach/u.c
	/n/sourcesdump/2006/0128/plan9/sys/src/libmach/u.c:109,115 - 
	/n/sourcesdump/2006/0129/plan9/sys/src/libmach/u.c:109,115
	  	0,		/* value */
	  	0x2000,		/* page size */
	  	0x80000000ULL,	/* kernel base */
	- 	0,		/* kernel text mask */
	+ 	0x80000000ULL,	/* kernel text mask */
	  	0x7FFFFFFFULL,	/* user stack top */
	  	4,		/* quantization of pc */
	  	4,		/* szaddr */