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cmd/5l: generate FreeBSD compatible ELF
1. correctly initialize .plt.got entries (point to the 1st entry) 2. add section .rel.plt (FreeBSD insists PLT relocs to be there) 3. put relocs of .got.plt into .rel.plt 4. set ELFOSABI_FREEBSD in ELF header R=rsc CC=golang-dev https://golang.org/cl/6643050
This commit is contained in:
Shenghou Ma
parent
fa563ae82e
commit
d901808869
@ -38,6 +38,7 @@
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static Prog *PP;
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char linuxdynld[] = "/lib/ld-linux.so.3"; // 2 for OABI, 3 for EABI
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char freebsddynld[] = "/usr/libexec/ld-elf.so.1";
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int32
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entryvalue(void)
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@ -344,13 +345,16 @@ addpltsym(Sym *s)
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if(iself) {
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plt = lookup(".plt", 0);
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got = lookup(".got.plt", 0);
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rel = lookup(".rel", 0);
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rel = lookup(".rel.plt", 0);
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if(plt->size == 0)
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elfsetupplt();
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// .got entry
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s->got = got->size;
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adduint32(got, 0);
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// In theory, all GOT should point to the first PLT entry,
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// Linux/ARM's dynamic linker will do that for us, but FreeBSD/ARM's
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// dynamic linker won't, so we'd better do it ourselves.
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addaddrplus(got, plt, 0);
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// .plt entry, this depends on the .got entry
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s->plt = plt->size;
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@ -696,7 +700,7 @@ asmb(void)
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/* !debug['d'] causes extra sections before the .text section */
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elftextsh = 2;
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if(!debug['d']) {
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elftextsh += 9;
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elftextsh += 10;
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if(elfverneed)
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elftextsh += 2;
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}
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@ -755,6 +759,9 @@ asmb(void)
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Bflush(&bso);
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cseek(0L);
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switch(HEADTYPE) {
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default:
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if(iself)
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goto Elfput;
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case Hnoheader: /* no header */
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break;
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case Hrisc: /* aif for risc os */
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@ -815,7 +822,7 @@ asmb(void)
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lputl(0xe3300000); /* nop */
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lputl(0xe3300000); /* nop */
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break;
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case Hlinux:
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Elfput:
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/* elf arm */
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eh = getElfEhdr();
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fo = HEADR;
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@ -851,8 +858,16 @@ asmb(void)
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sh->type = SHT_PROGBITS;
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sh->flags = SHF_ALLOC;
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sh->addralign = 1;
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if(interpreter == nil)
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interpreter = linuxdynld;
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if(interpreter == nil) {
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switch(HEADTYPE) {
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case Hlinux:
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interpreter = linuxdynld;
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break;
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case Hfreebsd:
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interpreter = freebsddynld;
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break;
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}
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}
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resoff -= elfinterp(sh, startva, resoff, interpreter);
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ph = newElfPhdr();
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@ -886,6 +901,31 @@ asmb(void)
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/* Dynamic linking sections */
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if(!debug['d']) { /* -d suppresses dynamic loader format */
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/* S headers for dynamic linking */
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dynsym = eh->shnum;
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sh = newElfShdr(elfstr[ElfStrDynsym]);
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sh->type = SHT_DYNSYM;
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sh->flags = SHF_ALLOC;
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sh->entsize = ELF32SYMSIZE;
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sh->addralign = 4;
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sh->link = dynsym+1; // dynstr
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// sh->info = index of first non-local symbol (number of local symbols)
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shsym(sh, lookup(".dynsym", 0));
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sh = newElfShdr(elfstr[ElfStrDynstr]);
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sh->type = SHT_STRTAB;
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sh->flags = SHF_ALLOC;
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sh->addralign = 1;
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shsym(sh, lookup(".dynstr", 0));
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sh = newElfShdr(elfstr[ElfStrRelPlt]);
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sh->type = SHT_REL;
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sh->flags = SHF_ALLOC;
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sh->entsize = ELF32RELSIZE;
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sh->addralign = 4;
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sh->link = dynsym;
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sh->info = eh->shnum; // .plt
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shsym(sh, lookup(".rel.plt", 0));
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// ARM ELF needs .plt to be placed before .got
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sh = newElfShdr(elfstr[ElfStrPlt]);
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sh->type = SHT_PROGBITS;
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@ -908,22 +948,6 @@ asmb(void)
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sh->addralign = 4;
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shsym(sh, lookup(".got", 0));
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dynsym = eh->shnum;
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sh = newElfShdr(elfstr[ElfStrDynsym]);
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sh->type = SHT_DYNSYM;
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sh->flags = SHF_ALLOC;
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sh->entsize = ELF32SYMSIZE;
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sh->addralign = 4;
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sh->link = dynsym+1; // dynstr
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// sh->info = index of first non-local symbol (number of local symbols)
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shsym(sh, lookup(".dynsym", 0));
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sh = newElfShdr(elfstr[ElfStrDynstr]);
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sh->type = SHT_STRTAB;
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sh->flags = SHF_ALLOC;
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sh->addralign = 1;
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shsym(sh, lookup(".dynstr", 0));
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if(elfverneed) {
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sh = newElfShdr(elfstr[ElfStrGnuVersion]);
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sh->type = SHT_GNU_VERSYM;
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@ -1029,6 +1053,11 @@ asmb(void)
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eh->ident[EI_CLASS] = ELFCLASS32;
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eh->ident[EI_DATA] = ELFDATA2LSB;
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eh->ident[EI_VERSION] = EV_CURRENT;
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switch(HEADTYPE) {
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case Hfreebsd:
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eh->ident[EI_OSABI] = ELFOSABI_FREEBSD;
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break;
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}
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eh->type = ET_EXEC;
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eh->machine = EM_ARM;
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@ -52,6 +52,7 @@ Header headers[] = {
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"ixp1200", Hixp1200,
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"ipaq", Hipaq,
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"linux", Hlinux,
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"freebsd", Hfreebsd,
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0, 0
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};
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@ -152,7 +153,7 @@ main(int argc, char *argv[])
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libinit();
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if(HEADTYPE == -1)
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HEADTYPE = Hlinux;
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HEADTYPE = headtype(goos);
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switch(HEADTYPE) {
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default:
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diag("unknown -H option");
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@ -212,6 +213,7 @@ main(int argc, char *argv[])
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INITRND = 1024;
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break;
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case Hlinux: /* arm elf */
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case Hfreebsd:
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debug['d'] = 0; // with dynamic linking
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tlsoffset = -8; // hardcoded number, first 4-byte word for g, and then 4-byte word for m
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// this number is known to ../../pkg/runtime/cgo/gcc_linux_arm.c
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