6l -e: emit external ELF symbol table.

enough to make nm and oprofile work.

R=r
http://go/go-review/1017016

src/cmd/6l/asm.c

@@ -255,6 +255,8 @@ enum {
 	ElfStrGosymtab,
 	ElfStrGopclntab,
 	ElfStrShstrtab,
+	ElfStrSymtab,
+	ElfStrStrtab,
 	NElfStr
 };
 
@@ -294,6 +296,10 @@ doelf(void)
 	if(!debug['s']) {
 		elfstr[ElfStrGosymtab] = addstring(shstrtab, ".gosymtab");
 		elfstr[ElfStrGopclntab] = addstring(shstrtab, ".gopclntab");
+		if(debug['e']) {
+			elfstr[ElfStrSymtab] = addstring(shstrtab, ".symtab");
+			elfstr[ElfStrStrtab] = addstring(shstrtab, ".strtab");
+		}
 	}
 	elfstr[ElfStrShstrtab] = addstring(shstrtab, ".shstrtab");
 
@@ -426,7 +432,7 @@ asmb(void)
 	int32 v, magic;
 	int a, dynsym;
 	uchar *op1;
-	vlong vl, va, startva, fo, w, symo, machlink;
+	vlong vl, va, startva, fo, w, symo, elfsymo, elfstro, elfsymsize, machlink;
 	vlong symdatva = 0x99LL<<32;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
@@ -436,6 +442,10 @@ asmb(void)
 		Bprint(&bso, "%5.2f asmb\n", cputime());
 	Bflush(&bso);
 
+	elftextsh = 0;
+	elfsymsize = 0;
+	elfstro = 0;
+	elfsymo = 0;
 	seek(cout, HEADR, 0);
 	pc = INITTEXT;
 	curp = firstp;
@@ -498,6 +508,12 @@ asmb(void)
 		debug['8'] = 1;	/* 64-bit addresses */
 		v = rnd(HEADR+textsize, INITRND);
 		seek(cout, v, 0);
+		
+		/* index of elf text section; needed by asmelfsym, double-checked below */
+		/* debug['d'] causes 8 extra sections before the .text section */
+		elftextsh = 1;
+		if(!debug['d'])
+			elftextsh += 8;
 		break;
 	}
 
@@ -546,6 +562,13 @@ asmb(void)
 			symo = rnd(symo, INITRND);
 			break;
 		}
+		/*
+		 * the symbol information is stored as
+		 *	32-bit symbol table size
+		 *	32-bit line number table size
+		 *	symbol table
+		 *	line number table
+		 */
 		seek(cout, symo+8, 0);
 		if(!debug['s'])
 			asmsym();
@@ -564,6 +587,15 @@ asmb(void)
 		lputl(symsize);
 		lputl(lcsize);
 		cflush();
+		if(!debug['s'] && debug['e']) {
+			elfsymo = symo+8+symsize+lcsize;
+			seek(cout, elfsymo, 0);
+			asmelfsym();
+			cflush();
+			elfstro = seek(cout, 0, 1);
+			elfsymsize = elfstro - elfsymo;
+			write(cout, elfstrdat, elfstrsize);
+		}		
 	} else
 	if(dlm){
 		seek(cout, HEADR+textsize+datsize, 0);
@@ -752,6 +784,8 @@ asmb(void)
 		va = startva + fo;
 		w = textsize;
 
+		if(elftextsh != eh->shnum)
+			diag("elftextsh = %d, want %d", elftextsh, eh->shnum);
 		sh = newElfShdr(elfstr[ElfStrText]);
 		sh->type = SHT_PROGBITS;
 		sh->flags = SHF_ALLOC+SHF_EXECINSTR;
@@ -802,6 +836,22 @@ asmb(void)
 			sh->off = fo;
 			sh->size = w;
 			sh->addralign = 1;
+			
+			if(debug['e']) {
+				sh = newElfShdr(elfstr[ElfStrSymtab]);
+				sh->type = SHT_SYMTAB;
+				sh->off = elfsymo;
+				sh->size = elfsymsize;
+				sh->addralign = 8;
+				sh->entsize = 24;
+				sh->link = eh->shnum;	// link to strtab
+			
+				sh = newElfShdr(elfstr[ElfStrStrtab]);
+				sh->type = SHT_STRTAB;
+				sh->off = elfstro;
+				sh->size = elfstrsize;
+				sh->addralign = 1;
+			}
 		}
 
 		sh = newElfShstrtab(elfstr[ElfStrShstrtab]);

src/cmd/6l/l.h

@@ -350,6 +350,9 @@ EXTERN	vlong	textstksiz;
 EXTERN	vlong	textarg;
 extern	char	thechar;
 EXTERN	int	dynptrsize;
+EXTERN	int	elfstrsize;
+EXTERN	char*	elfstrdat;
+EXTERN	int	elftextsh;
 
 #define	UP	(&undefp)
 
@@ -376,6 +379,7 @@ void	asmins(Prog*);
 void	asmlc(void);
 void	asmsp(void);
 void	asmsym(void);
+void	asmelfsym(void);
 vlong	atolwhex(char*);
 Prog*	brchain(Prog*);
 Prog*	brloop(Prog*);

src/cmd/6l/span.c

@@ -30,6 +30,7 @@
 
 #include	"l.h"
 #include	"../ld/lib.h"
+#include	"../ld/elf.h"
 
 static int	rexflag;
 static int	asmode;
@@ -151,7 +152,7 @@ xdefine(char *p, int t, vlong v)
 }
 
 void
-putsymb(char *s, int t, vlong v, int ver, Sym *go)
+putsymb(char *s, int t, vlong v, vlong size, int ver, Sym *go)
 {
 	int i, f, l;
 	vlong gv;
@@ -212,7 +213,7 @@ putsymb(char *s, int t, vlong v, int ver, Sym *go)
 }
 
 void
-asmsym(void)
+genasmsym(void (*put)(char*, int, vlong, vlong, int, Sym*))
 {
 	Prog *p;
 	Auto *a;
@@ -221,7 +222,7 @@ asmsym(void)
 
 	s = lookup("etext", 0);
 	if(s->type == STEXT)
-		putsymb(s->name, 'T', s->value, s->version, 0);
+		put(s->name, 'T', s->value, s->size, s->version, 0);
 
 	for(h=0; h<NHASH; h++) {
 		for(s=hash[h]; s!=S; s=s->link) {
@@ -229,29 +230,29 @@ asmsym(void)
 			case SCONST:
 				if(!s->reachable)
 					continue;
-				putsymb(s->name, 'D', s->value, s->version, s->gotype);
+				put(s->name, 'D', s->value, s->size, s->version, s->gotype);
 				continue;
 
 			case SDATA:
 				if(!s->reachable)
 					continue;
-				putsymb(s->name, 'D', s->value+INITDAT, s->version, s->gotype);
+				put(s->name, 'D', s->value+INITDAT, s->size, s->version, s->gotype);
 				continue;
 
 			case SMACHO:
 				if(!s->reachable)
 					continue;
-				putsymb(s->name, 'D', s->value+INITDAT+datsize+bsssize, s->version, s->gotype);
+				put(s->name, 'D', s->value+INITDAT+datsize+bsssize, s->size, s->version, s->gotype);
 				continue;
 
 			case SBSS:
 				if(!s->reachable)
 					continue;
-				putsymb(s->name, 'B', s->value+INITDAT, s->version, s->gotype);
+				put(s->name, 'B', s->value+INITDAT, s->size, s->version, s->gotype);
 				continue;
 
 			case SFILE:
-				putsymb(s->name, 'f', s->value, s->version, 0);
+				put(s->name, 'f', s->value, 0, s->version, 0);
 				continue;
 			}
 		}
@@ -265,30 +266,99 @@ asmsym(void)
 		/* filenames first */
 		for(a=p->to.autom; a; a=a->link)
 			if(a->type == D_FILE)
-				putsymb(a->asym->name, 'z', a->aoffset, 0, 0);
+				put(a->asym->name, 'z', a->aoffset, 0, 0, 0);
 			else
 			if(a->type == D_FILE1)
-				putsymb(a->asym->name, 'Z', a->aoffset, 0, 0);
+				put(a->asym->name, 'Z', a->aoffset, 0, 0, 0);
 
 		if(!s->reachable)
 			continue;
-		putsymb(s->name, 'T', s->value, s->version, s->gotype);
+		put(s->name, 'T', s->value, s->size, s->version, s->gotype);
 
 		/* frame, auto and param after */
-		putsymb(".frame", 'm', p->to.offset+8, 0, 0);
+		put(".frame", 'm', p->to.offset+8, 0, 0, 0);
 
 		for(a=p->to.autom; a; a=a->link)
 			if(a->type == D_AUTO)
-				putsymb(a->asym->name, 'a', -a->aoffset, 0, a->gotype);
+				put(a->asym->name, 'a', -a->aoffset, 0, 0, a->gotype);
 			else
 			if(a->type == D_PARAM)
-				putsymb(a->asym->name, 'p', a->aoffset, 0, a->gotype);
+				put(a->asym->name, 'p', a->aoffset, 0, 0, a->gotype);
 	}
 	if(debug['v'] || debug['n'])
 		Bprint(&bso, "symsize = %lud\n", symsize);
 	Bflush(&bso);
 }
 
+void
+asmsym(void)
+{
+	genasmsym(putsymb);
+}
+
+char *elfstrdat;
+int elfstrsize;
+int maxelfstr;
+
+int
+putelfstr(char *s)
+{
+	int off, n;
+
+	if(elfstrsize == 0 && s[0] != 0) {
+		// first entry must be empty string
+		putelfstr("");
+	}
+
+	n = strlen(s)+1;
+	if(elfstrsize+n > maxelfstr) {
+		maxelfstr = 2*(elfstrsize+n+(1<<20));
+		elfstrdat = realloc(elfstrdat, maxelfstr);
+	}
+	off = elfstrsize;
+	elfstrsize += n;
+	memmove(elfstrdat+off, s, n);
+	return off;
+}
+
+void
+putelfsymb(char *s, int t, vlong addr, vlong size, int ver, Sym *go)
+{
+	int bind, type, shndx, stroff;
+	
+	bind = STB_GLOBAL;
+	switch(t) {
+	default:
+		return;
+	case 'T':
+		type = STT_FUNC;
+		shndx = elftextsh + 0;
+		break;
+	case 'D':
+		type = STT_OBJECT;
+		shndx = elftextsh + 1;
+		break;
+	case 'B':
+		type = STT_OBJECT;
+		shndx = elftextsh + 2;
+		break;
+	}
+	
+	stroff = putelfstr(s);
+	lputl(stroff);	// string
+	cput((bind<<4)|(type&0xF));
+	cput(0);
+	wputl(shndx);
+	vputl(addr);
+	vputl(size);
+}
+
+void
+asmelfsym(void)
+{
+	genasmsym(putelfsymb);
+}
+
 void
 asmlc(void)
 {

src/cmd/ld/elf.c

@@ -11,7 +11,7 @@
  * in order to write the code just once.  The 64-bit data structure is
  * written in the 32-bit format on the 32-bit machines.
  */
-#define	NSECT	16
+#define	NSECT	32
 
 static	int	elf64;
 static	ElfEhdr	hdr;