Author: andrew Date: Fri Apr 3 09:35:52 2015 New Revision: 281014 URL: https://svnweb.freebsd.org/changeset/base/281014
Log: Add support for thread local storage on arm64 to the runtime linker. The ABI specifies that, for R_AARCH64_TLSDESC relocations, we use the symbol value, addend, and object tls offset to calculate the offset from the tls base. We then cache this value for future reference. Differential Revision: https://reviews.freebsd.org/D2183 Reviewed by: kib Sponsored by: The FreeBSD Foundation Modified: head/libexec/rtld-elf/aarch64/reloc.c head/libexec/rtld-elf/aarch64/rtld_start.S Modified: head/libexec/rtld-elf/aarch64/reloc.c ============================================================================== --- head/libexec/rtld-elf/aarch64/reloc.c Fri Apr 3 06:17:24 2015 (r281013) +++ head/libexec/rtld-elf/aarch64/reloc.c Fri Apr 3 09:35:52 2015 (r281014) @@ -50,6 +50,8 @@ __FBSDID("$FreeBSD$"); * a function pointer to a simple asm function. */ void *_rtld_tlsdesc(void *); +void *_rtld_tlsdesc_dynamic(void *); + void _exit(int); void @@ -120,6 +122,68 @@ do_copy_relocations(Obj_Entry *dstobj) return (0); } +struct tls_data { + int64_t index; + Obj_Entry *obj; + const Elf_Rela *rela; +}; + +static struct tls_data * +reloc_tlsdesc_alloc(Obj_Entry *obj, const Elf_Rela *rela) +{ + struct tls_data *tlsdesc; + + tlsdesc = xmalloc(sizeof(struct tls_data)); + tlsdesc->index = -1; + tlsdesc->obj = obj; + tlsdesc->rela = rela; + + return (tlsdesc); +} + +/* + * Look up the symbol to find its tls index + */ +static int64_t +rtld_tlsdesc_handle_locked(struct tls_data *tlsdesc, int flags, + RtldLockState *lockstate) +{ + const Elf_Rela *rela; + const Elf_Sym *def; + const Obj_Entry *defobj; + Obj_Entry *obj; + + rela = tlsdesc->rela; + obj = tlsdesc->obj; + + def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, NULL, + lockstate); + if (def == NULL) + rtld_die(); + + tlsdesc->index = defobj->tlsindex + def->st_value + rela->r_addend; + + return (tlsdesc->index); +} + +int64_t +rtld_tlsdesc_handle(struct tls_data *tlsdesc, int flags) +{ + RtldLockState lockstate; + + /* We have already found the index, return it */ + if (tlsdesc->index >= 0) + return (tlsdesc->index); + + wlock_acquire(rtld_bind_lock, &lockstate); + /* tlsdesc->index may have been set by another thread */ + if (tlsdesc->index == -1) + rtld_tlsdesc_handle_locked(tlsdesc, flags, &lockstate); + lock_release(rtld_bind_lock, &lockstate); + + return (tlsdesc->index); +} + /* * Process the PLT relocations. */ @@ -142,11 +206,11 @@ reloc_plt(Obj_Entry *obj) case R_AARCH64_TLSDESC: if (ELF_R_SYM(rela->r_info) == 0) { where[0] = (Elf_Addr)_rtld_tlsdesc; - where[1] = rela->r_addend; + where[1] = obj->tlsindex + rela->r_addend; } else { - _rtld_error("Unable to handle " - "R_AARCH64_TLSDESC with a symbol set"); - return (-1); + where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic; + where[1] = (Elf_Addr)reloc_tlsdesc_alloc(obj, + rela); } break; default: @@ -169,14 +233,15 @@ reloc_jmpslots(Obj_Entry *obj, int flags const Elf_Rela *relalim; const Elf_Rela *rela; const Elf_Sym *def; + struct tls_data *tlsdesc; relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { Elf_Addr *where; + where = (Elf_Addr *)(obj->relocbase + rela->r_offset); switch(ELF_R_TYPE(rela->r_info)) { case R_AARCH64_JUMP_SLOT: - where = (Elf_Addr *)(obj->relocbase + rela->r_offset); def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate); if (def == NULL) { @@ -187,6 +252,12 @@ reloc_jmpslots(Obj_Entry *obj, int flags *where = (Elf_Addr)(defobj->relocbase + def->st_value); break; case R_AARCH64_TLSDESC: + if (ELF_R_SYM(rela->r_info) != 0) { + tlsdesc = (struct tls_data *)where[1]; + if (tlsdesc->index == -1) + rtld_tlsdesc_handle_locked(tlsdesc, + SYMLOOK_IN_PLT | flags, lockstate); + } break; default: _rtld_error("Unknown relocation type %x in jmpslot", @@ -285,6 +356,32 @@ reloc_non_plt(Obj_Entry *obj, Obj_Entry return (-1); } break; + case R_AARCH64_TLS_TPREL64: + def = find_symdef(symnum, obj, &defobj, flags, cache, + lockstate); + if (def == NULL) + return (-1); + + /* + * We lazily allocate offsets for static TLS as we + * see the first relocation that references the + * TLS block. This allows us to support (small + * amounts of) static TLS in dynamically loaded + * modules. If we run out of space, we generate an + * error. + */ + if (!defobj->tls_done) { + if (!allocate_tls_offset((Obj_Entry*) defobj)) { + _rtld_error( + "%s: No space available for static " + "Thread Local Storage", obj->path); + return (-1); + } + } + + *where = def->st_value + rela->r_addend + + defobj->tlsoffset - TLS_TCB_SIZE; + break; case R_AARCH64_RELATIVE: *where = (Elf_Addr)(obj->relocbase + rela->r_addend); break; Modified: head/libexec/rtld-elf/aarch64/rtld_start.S ============================================================================== --- head/libexec/rtld-elf/aarch64/rtld_start.S Fri Apr 3 06:17:24 2015 (r281013) +++ head/libexec/rtld-elf/aarch64/rtld_start.S Fri Apr 3 09:35:52 2015 (r281014) @@ -109,5 +109,44 @@ END(_rtld_bind_start) */ ENTRY(_rtld_tlsdesc) ldr x0, [x0, #8] - RET + ret END(_rtld_tlsdesc) + +/* + * uint64_t _rtld_tlsdesc_dynamic(struct tlsdesc *); + * + * TODO: We could lookup the saved index here to skip saving the entire stack. + */ +ENTRY(_rtld_tlsdesc_dynamic) + /* Store any registers we may use in rtld_tlsdesc_handle */ + stp x29, x30, [sp, #-(10 * 16)]! + mov x29, sp + stp x1, x2, [sp, #(1 * 16)] + stp x3, x4, [sp, #(2 * 16)] + stp x5, x6, [sp, #(3 * 16)] + stp x7, x8, [sp, #(4 * 16)] + stp x9, x10, [sp, #(5 * 16)] + stp x11, x12, [sp, #(6 * 16)] + stp x13, x14, [sp, #(7 * 16)] + stp x15, x16, [sp, #(8 * 16)] + stp x17, x18, [sp, #(9 * 16)] + + /* Find the tls offset */ + ldr x0, [x0, #8] + mov x1, #1 + bl rtld_tlsdesc_handle + + /* Restore the registers */ + ldp x17, x18, [sp, #(9 * 16)] + ldp x15, x16, [sp, #(8 * 16)] + ldp x13, x14, [sp, #(7 * 16)] + ldp x11, x12, [sp, #(6 * 16)] + ldp x9, x10, [sp, #(5 * 16)] + ldp x7, x8, [sp, #(4 * 16)] + ldp x5, x6, [sp, #(3 * 16)] + ldp x3, x4, [sp, #(2 * 16)] + ldp x1, x2, [sp, #(1 * 16)] + ldp x29, x30, [sp], #(10 * 16) + + ret +END(_rtld_tlsdesc_dynamic) _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
