5l/6l/8l: add support for netbsd signature note section

R=m4dh4tt3r, jsing, rsc
CC=golang-dev
https://golang.org/cl/5493068

src/cmd/5l/asm.c

@@ -73,6 +73,7 @@ enum {
 	ElfStrShstrtab,
 	ElfStrRelPlt,
 	ElfStrPlt,
+	ElfStrNoteNetbsdIdent,
 	NElfStr
 };
 
@@ -164,6 +165,8 @@ doelf(void)
 	elfstr[ElfStrText] = addstring(shstrtab, ".text");
 	elfstr[ElfStrData] = addstring(shstrtab, ".data");
 	elfstr[ElfStrBss] = addstring(shstrtab, ".bss");
+	if(HEADTYPE == Hnetbsd)
+		elfstr[ElfStrNoteNetbsdIdent] = addstring(shstrtab, ".note.netbsd.ident");
 	addstring(shstrtab, ".rodata");
 	addstring(shstrtab, ".gosymtab");
 	addstring(shstrtab, ".gopclntab");
@@ -294,7 +297,7 @@ asmb(void)
 {
 	int32 t;
 	int a, dynsym;
-	uint32 fo, symo, startva;
+	uint32 fo, symo, startva, resoff;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -336,6 +339,8 @@ asmb(void)
 			if(elfverneed)
 				elftextsh += 2;
 		}
+		if(HEADTYPE == Hnetbsd)
+			elftextsh += 1;
 	}
 
 	/* output symbol table */
@@ -371,7 +376,7 @@ asmb(void)
 		cseek(symo);
 		if(iself) {
 			if(debug['v'])
-			       Bprint(&bso, "%5.2f elfsym\n", cputime());
+				Bprint(&bso, "%5.2f elfsym\n", cputime());
 			asmelfsym();
 			cflush();
 			cwrite(elfstrdat, elfstrsize);
@@ -455,6 +460,7 @@ asmb(void)
 		eh = getElfEhdr();
 		fo = HEADR;
 		startva = INITTEXT - fo;	/* va of byte 0 of file */
+		resoff = ELFRESERVE;
 		
 		/* This null SHdr must appear before all others */
 		newElfShdr(elfstr[ElfStrEmpty]);
@@ -487,7 +493,7 @@ asmb(void)
 			sh->addralign = 1;
 			if(interpreter == nil)
 				interpreter = linuxdynld;
-			elfinterp(sh, startva, interpreter);
+			resoff -= elfinterp(sh, startva, resoff, interpreter);
 
 			ph = newElfPhdr();
 			ph->type = PT_INTERP;
@@ -495,11 +501,24 @@ asmb(void)
 			phsh(ph, sh);
 		}
 
+		if(HEADTYPE == Hnetbsd) {
+			sh = newElfShdr(elfstr[ElfStrNoteNetbsdIdent]);
+			sh->type = SHT_NOTE;
+			sh->flags = SHF_ALLOC;
+			sh->addralign = 4;
+			resoff -= elfnetbsdsig(sh, startva, resoff);
+
+			ph = newElfPhdr();
+			ph->type = PT_NOTE;
+			ph->flags = PF_R;
+			phsh(ph, sh);
+		}
+
 		elfphload(&segtext);
 		elfphload(&segdata);
 
 		/* Dynamic linking sections */
-		if (!debug['d']) {	/* -d suppresses dynamic loader format */
+		if(!debug['d']) {	/* -d suppresses dynamic loader format */
 			/* S headers for dynamic linking */
 			sh = newElfShdr(elfstr[ElfStrGot]);
 			sh->type = SHT_PROGBITS;
@@ -590,7 +609,7 @@ asmb(void)
 		for(sect=segdata.sect; sect!=nil; sect=sect->next)
 			elfshbits(sect);
 
-		if (!debug['s']) {
+		if(!debug['s']) {
 			sh = newElfShdr(elfstr[ElfStrSymtab]);
 			sh->type = SHT_SYMTAB;
 			sh->off = symo;
@@ -632,7 +651,9 @@ asmb(void)
 		a += elfwritehdr();
 		a += elfwritephdrs();
 		a += elfwriteshdrs();
-		a += elfwriteinterp();
+		a += elfwriteinterp(elfstr[ElfStrInterp]);
+		if(HEADTYPE == Hnetbsd)
+			a += elfwritenetbsdsig(elfstr[ElfStrNoteNetbsdIdent]);
 		if(a > ELFRESERVE)	
 			diag("ELFRESERVE too small: %d > %d", a, ELFRESERVE);
 		break;

src/cmd/6l/asm.c

@@ -707,7 +707,7 @@ asmb(void)
 {
 	int32 magic;
 	int a, dynsym;
-	vlong vl, startva, symo, dwarfoff, machlink;
+	vlong vl, startva, symo, dwarfoff, machlink, resoff;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -778,6 +778,8 @@ asmb(void)
 			if(elfverneed)
 				elftextsh += 2;
 		}
+		if(HEADTYPE == Hnetbsd)
+			elftextsh += 1;
 		break;
 	case Hwindows:
 		break;
@@ -879,6 +881,7 @@ asmb(void)
 
 		eh = getElfEhdr();
 		startva = INITTEXT - HEADR;
+		resoff = ELFRESERVE;
 
 		/* This null SHdr must appear before all others */
 		newElfShdr(elfstr[ElfStrEmpty]);
@@ -925,7 +928,7 @@ asmb(void)
 					break;
 				}
 			}
-			elfinterp(sh, startva, interpreter);
+			resoff -= elfinterp(sh, startva, resoff, interpreter);
 
 			ph = newElfPhdr();
 			ph->type = PT_INTERP;
@@ -933,11 +936,24 @@ asmb(void)
 			phsh(ph, sh);
 		}
 
+		if(HEADTYPE == Hnetbsd) {
+			sh = newElfShdr(elfstr[ElfStrNoteNetbsdIdent]);
+			sh->type = SHT_NOTE;
+			sh->flags = SHF_ALLOC;
+			sh->addralign = 4;
+			resoff -= elfnetbsdsig(sh, startva, resoff);
+
+			ph = newElfPhdr();
+			ph->type = PT_NOTE;
+			ph->flags = PF_R;
+			phsh(ph, sh);
+		}
+
 		elfphload(&segtext);
 		elfphload(&segdata);
 
 		/* Dynamic linking sections */
-		if (!debug['d']) {	/* -d suppresses dynamic loader format */
+		if(!debug['d']) {	/* -d suppresses dynamic loader format */
 			/* S headers for dynamic linking */
 			sh = newElfShdr(elfstr[ElfStrGot]);
 			sh->type = SHT_PROGBITS;
@@ -1061,7 +1077,7 @@ asmb(void)
 		for(sect=segdata.sect; sect!=nil; sect=sect->next)
 			elfshbits(sect);
 
-		if (!debug['s']) {
+		if(!debug['s']) {
 			sh = newElfShdr(elfstr[ElfStrSymtab]);
 			sh->type = SHT_SYMTAB;
 			sh->off = symo;
@@ -1107,7 +1123,9 @@ asmb(void)
 		a += elfwritehdr();
 		a += elfwritephdrs();
 		a += elfwriteshdrs();
-		a += elfwriteinterp();
+		a += elfwriteinterp(elfstr[ElfStrInterp]);
+		if(HEADTYPE == Hnetbsd)
+			a += elfwritenetbsdsig(elfstr[ElfStrNoteNetbsdIdent]);
 		if(a > ELFRESERVE)	
 			diag("ELFRESERVE too small: %d > %d", a, ELFRESERVE);
 		break;

src/cmd/8l/asm.c

@@ -92,6 +92,7 @@ enum {
 	ElfStrPlt,
 	ElfStrGnuVersion,
 	ElfStrGnuVersionR,
+	ElfStrNoteNetbsdIdent,
 	NElfStr
 };
 
@@ -528,6 +529,8 @@ doelf(void)
 	elfstr[ElfStrText] = addstring(shstrtab, ".text");
 	elfstr[ElfStrData] = addstring(shstrtab, ".data");
 	elfstr[ElfStrBss] = addstring(shstrtab, ".bss");
+	if(HEADTYPE == Hnetbsd)
+		elfstr[ElfStrNoteNetbsdIdent] = addstring(shstrtab, ".note.netbsd.ident");
 	addstring(shstrtab, ".elfdata");
 	addstring(shstrtab, ".rodata");
 	addstring(shstrtab, ".gosymtab");
@@ -661,7 +664,7 @@ asmb(void)
 {
 	int32 v, magic;
 	int a, dynsym;
-	uint32 symo, startva, dwarfoff, machlink;
+	uint32 symo, startva, dwarfoff, machlink, resoff;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -715,6 +718,8 @@ asmb(void)
 			if(elfverneed)
 				elftextsh += 2;
 		}
+		if(HEADTYPE == Hnetbsd)
+			elftextsh += 1;
 	}
 
 	symsize = 0;
@@ -761,7 +766,7 @@ asmb(void)
 		default:
 			if(iself) {
 				if(debug['v'])
-				       Bprint(&bso, "%5.2f elfsym\n", cputime());
+					Bprint(&bso, "%5.2f elfsym\n", cputime());
 				asmelfsym();
 				cflush();
 				cwrite(elfstrdat, elfstrsize);
@@ -932,6 +937,7 @@ asmb(void)
 	Elfput:
 		eh = getElfEhdr();
 		startva = INITTEXT - HEADR;
+		resoff = ELFRESERVE;
 
 		/* This null SHdr must appear before all others */
 		newElfShdr(elfstr[ElfStrEmpty]);
@@ -978,7 +984,7 @@ asmb(void)
 					break;
 				}
 			}
-			elfinterp(sh, startva, interpreter);
+			resoff -= elfinterp(sh, startva, resoff, interpreter);
 
 			ph = newElfPhdr();
 			ph->type = PT_INTERP;
@@ -986,11 +992,24 @@ asmb(void)
 			phsh(ph, sh);
 		}
 
+		if(HEADTYPE == Hnetbsd) {
+			sh = newElfShdr(elfstr[ElfStrNoteNetbsdIdent]);
+			sh->type = SHT_NOTE;
+			sh->flags = SHF_ALLOC;
+			sh->addralign = 4;
+			resoff -= elfnetbsdsig(sh, startva, resoff);
+
+			ph = newElfPhdr();
+			ph->type = PT_NOTE;
+			ph->flags = PF_R;
+			phsh(ph, sh);
+		}
+
 		elfphload(&segtext);
 		elfphload(&segdata);
 
 		/* Dynamic linking sections */
-		if (!debug['d']) {	/* -d suppresses dynamic loader format */
+		if(!debug['d']) {	/* -d suppresses dynamic loader format */
 			/* S headers for dynamic linking */
 			sh = newElfShdr(elfstr[ElfStrGot]);
 			sh->type = SHT_PROGBITS;
@@ -1114,7 +1133,7 @@ asmb(void)
 		for(sect=segdata.sect; sect!=nil; sect=sect->next)
 			elfshbits(sect);
 
-		if (!debug['s']) {
+		if(!debug['s']) {
 			sh = newElfShdr(elfstr[ElfStrSymtab]);
 			sh->type = SHT_SYMTAB;
 			sh->off = symo;
@@ -1167,7 +1186,9 @@ asmb(void)
 		a += elfwritehdr();
 		a += elfwritephdrs();
 		a += elfwriteshdrs();
-		a += elfwriteinterp();
+		a += elfwriteinterp(elfstr[ElfStrInterp]);
+		if(HEADTYPE == Hnetbsd)
+			a += elfwritenetbsdsig(elfstr[ElfStrNoteNetbsdIdent]);
 		if(a > ELFRESERVE)	
 			diag("ELFRESERVE too small: %d > %d", a, ELFRESERVE);
 		break;

src/cmd/ld/elf.c

@@ -318,29 +318,77 @@ elfwritedynentsymsize(Sym *s, int tag, Sym *t)
 }
 
 int
-elfwriteinterp(void)
+elfinterp(ElfShdr *sh, uint64 startva, uint64 resoff, char *p)
 {
 	int n;
 
-	if(interp == nil)
-		return 0;
-
+	interp = p;
 	n = strlen(interp)+1;
-	cseek(ELFRESERVE-n);
-	cwrite(interp, n);
+	sh->addr = startva + resoff - n;
+	sh->off = resoff - n;
+	sh->size = n;
+
 	return n;
 }
 
-void
-elfinterp(ElfShdr *sh, uint64 startva, char *p)
+int
+elfwriteinterp(vlong stridx)
+{
+	ElfShdr *sh = nil;
+	int i;
+
+	for(i = 0; i < hdr.shnum; i++)
+		if(shdr[i]->name == stridx)
+			sh = shdr[i];
+	if(sh == nil || interp == nil)
+		return 0;
+
+	cseek(sh->off);
+	cwrite(interp, sh->size);
+	return sh->size;
+}
+
+// Defined in NetBSD's sys/exec_elf.h
+#define ELF_NOTE_TYPE_NETBSD_TAG	1
+#define ELF_NOTE_NETBSD_NAMESZ		7
+#define ELF_NOTE_NETBSD_DESCSZ		4
+#define ELF_NOTE_NETBSD_NAME		"NetBSD\0\0"
+#define ELF_NOTE_NETBSD_VERSION		599000000	/* NetBSD 5.99 */
+
+int
+elfnetbsdsig(ElfShdr *sh, uint64 startva, uint64 resoff)
 {
 	int n;
 
-	interp = p;
-	n = strlen(interp)+1;
-	sh->addr = startva + ELFRESERVE - n;
-	sh->off = ELFRESERVE - n;
+	n = sizeof(Elf_Note) + ELF_NOTE_NETBSD_NAMESZ + ELF_NOTE_NETBSD_DESCSZ + 1;
+	n += resoff % 4;
+	sh->addr = startva + resoff - n;
+	sh->off = resoff - n;
 	sh->size = n;
+
+	return n;
+}
+
+int
+elfwritenetbsdsig(vlong stridx) {
+	ElfShdr *sh = nil;
+	int i;
+
+	for(i = 0; i < hdr.shnum; i++)
+		if(shdr[i]->name == stridx)
+			sh = shdr[i];
+	if(sh == nil)
+		return 0;
+
+	// Write Elf_Note header followed by NetBSD string.
+	cseek(sh->off);
+	LPUT(ELF_NOTE_NETBSD_NAMESZ);
+	LPUT(ELF_NOTE_NETBSD_DESCSZ);
+	LPUT(ELF_NOTE_TYPE_NETBSD_TAG);
+	cwrite(ELF_NOTE_NETBSD_NAME, 8);
+	LPUT(ELF_NOTE_NETBSD_VERSION);
+
+	return sh->size;
 }
 
 extern int nelfsym;

src/cmd/ld/elf.h

@@ -968,8 +968,10 @@ extern	int	numelfphdr;
 extern	int	numelfshdr;
 extern	int	iself;
 extern	int	elfverneed;
-int	elfwriteinterp(void);
-void	elfinterp(ElfShdr*, uint64, char*);
+int	elfinterp(ElfShdr*, uint64, uint64, char*);
+int	elfwriteinterp(vlong);
+int	elfnetbsdsig(ElfShdr*, uint64, uint64);
+int	elfwritenetbsdsig(vlong);
 void	elfdynhash(void);
 ElfPhdr* elfphload(Segment*);
 ElfShdr* elfshbits(Section*);