svn commit: r281014 - head/libexec/rtld-elf/aarch64
Andrew Turner
andrew at FreeBSD.org
Fri Apr 3 09:35:54 UTC 2015
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)
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