/* $NetBSD: rtld_start.S,v 1.7 2024/07/23 18:11:53 riastradh Exp $ */ /*- * Copyright (c) 2014 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Matt Thomas of 3am Software Foundry. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /*- * Copyright (c) 2014 The FreeBSD Foundation * All rights reserved. * * This software was developed by Andrew Turner under * sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <machine/asm.h> RCSID("$NetBSD: rtld_start.S,v 1.7 2024/07/23 18:11:53 riastradh Exp $") /* * void _rtld_start(void (*cleanup)(void), const Obj_Entry *obj, * struct ps_strings *ps_strings); * * X0 = NULL * X1 = NULL * X2 = ps_strings * X30 (LR) = 0 * X29 (FP) = 0 */ ENTRY_NP(_rtld_start) mov x24, x2 /* save ps_strings */ adrp x1, :got:_DYNAMIC /* load _DYNAMIC offset from GOT */ ldr x1, [x1, #:got_lo12:_DYNAMIC] adrp x0, _DYNAMIC /* get &_DYNAMIC */ add x0, x0, #:lo12:_DYNAMIC sub x25, x0, x1 /* relocbase = &_DYNAMIC - GOT:_DYNAMIC */ mov x1, x25 /* pass as 2nd argument */ bl _C_LABEL(_rtld_relocate_nonplt_self) sub sp, sp, #16 /* reserve space for returns */ mov x0, sp /* pointer to reserved space */ mov x1, x25 /* pass relocbase */ bl _C_LABEL(_rtld) mov x17, x0 /* save entry point */ ldp x0, x1, [sp], #16 /* pop cleanup & obj_main */ mov x2, x24 /* restore ps_strings */ br x17 /* call saved entry point */ END(_rtld_start) /* * Upon entry from plt0 entry: * * SP+0 = &PLTGOT[n + 3] * SP+8 = return addr * X16 = &PLTGOT[2] */ ENTRY_NP(_rtld_bind_start) ldr x9, [sp] /* x9 = &PLTGOT[n+3] */ /* save x0-x8 for arguments */ stp x0, x1, [sp, #-16]! stp x2, x3, [sp, #-16]! stp x4, x5, [sp, #-16]! stp x6, x7, [sp, #-16]! stp x8, xzr, [sp, #-16]! /* save q0-q7 for arguments */ stp q0, q1, [sp, #-32]! stp q2, q3, [sp, #-32]! stp q4, q5, [sp, #-32]! stp q6, q7, [sp, #-32]! ldr x0, [x16, #-8] /* x0 = PLTGOT[1] */ sub x1, x9, x16 /* x1 = &PLTGOT[n+3] - &PLTGOT[1] = offset+8 */ sub x1, x1, #8 /* x1 = offset */ lsr x1, x1, #3 /* x1 /= sizeof(void *) */ bl _C_LABEL(_rtld_bind) mov x17, x0 /* save result */ /* restore q0-q7 for arguments */ ldp q6, q7, [sp], #32 ldp q4, q5, [sp], #32 ldp q2, q3, [sp], #32 ldp q0, q1, [sp], #32 /* restore x0-x8 for arguments */ ldp x8, xzr, [sp], #16 ldp x6, x7, [sp], #16 ldp x4, x5, [sp], #16 ldp x2, x3, [sp], #16 ldp x0, x1, [sp], #16 ldp xzr, lr, [sp], #16 /* restore original lr pushed by plt0 */ br x17 /* call bound function */ END(_rtld_bind_start) /* * Entry points used by _rtld_tlsdesc_fill. They will be passed in x0 * a pointer to: * * struct rel_tlsdesc { * uint64_t resolver_fnc; * uint64_t resolver_arg; * }; * * They are called with nonstandard calling convention and must * preserve all registers except x0. */ /* * uint64_t@x0 * _rtld_tlsdesc_static(struct rel_tlsdesc *rel_tlsdesc@x0); * * Resolver function for TLS symbols resolved at load time. * * rel_tlsdesc->resolver_arg is the offset of the static * thread-local storage region, relative to the start of the TCB. * * Nonstandard calling convention: Must preserve all registers * except x0. */ ENTRY(_rtld_tlsdesc_static) .cfi_startproc ldr x0, [x0, #8] /* x0 := tcboffset */ ret /* return x0 = tcboffset */ .cfi_endproc END(_rtld_tlsdesc_static) /* * uint64_t@x0 * _rtld_tlsdesc_undef(struct rel_tlsdesc *rel_tlsdesc@x0); * * Resolver function for weak and undefined TLS symbols. * * rel_tlsdesc->resolver_arg is the Elf_Rela rela->r_addend. * * Nonstandard calling convention: Must preserve all registers * except x0. */ ENTRY(_rtld_tlsdesc_undef) .cfi_startproc str x1, [sp, #-16]! /* save x1 on stack */ .cfi_adjust_cfa_offset 16 mrs x1, tpidr_el0 /* x1 := current thread tcb */ ldr x0, [x0, #8] /* x0 := rela->r_addend */ sub x0, x0, x1 /* x0 := rela->r_addend - tcb */ ldr x1, [sp], #16 /* restore x1 from stack */ .cfi_adjust_cfa_offset -16 .cfi_endproc ret /* return x0 = rela->r_addend - tcb */ END(_rtld_tlsdesc_undef) /* * uint64_t@x0 * _rtld_tlsdesc_dynamic(struct rel_tlsdesc *tlsdesc@x0); * * Resolver function for TLS symbols from dlopen(). * * rel_tlsdesc->resolver_arg is a pointer to a struct tls_data * object allocated during relocation. * * Nonstandard calling convention: Must preserve all registers * except x0. */ ENTRY(_rtld_tlsdesc_dynamic) .cfi_startproc /* Save registers used in fast path */ stp x1, x2, [sp, #(-2 * 16)]! stp x3, x4, [sp, #(1 * 16)] .cfi_adjust_cfa_offset 2 * 16 .cfi_rel_offset x1, 0 .cfi_rel_offset x2, 8 .cfi_rel_offset x3, 16 .cfi_rel_offset x4, 24 /* Try for the fast path -- inlined version of __tls_get_addr. */ ldr x1, [x0, #8] /* x1 := tlsdesc (struct tls_data *) */ mrs x4, tpidr_el0 /* x4 := tcb */ ldr x0, [x4] /* x0 := dtv = tcb->tcb_dtv */ ldr x3, [x0, #-8] /* x3 := max = DTV_MAX_INDEX(dtv) */ ldr x2, [x1, #0] /* x2 := idx = tlsdesc->td_tlsindex */ cmp x2, x3 b.gt 1f /* Slow path if idx > max */ ldr x3, [x0, x2, lsl #3] /* x3 := dtv[idx] */ cbz x3, 1f /* Slow path if dtv[idx] is null */ /* * Fast path * * return (dtv[tlsdesc->td_tlsindex] + tlsdesc->td_tlsoffs - tcb) */ ldr x2, [x1, #8] /* x2 := offs = tlsdesc->td_tlsoffs */ add x2, x2, x3 /* x2 := addr = dtv[idx] + offs */ sub x0, x2, x4 /* x0 := addr - tcb /* Restore fast path registers and return */ ldp x3, x4, [sp, #(1 * 16)] ldp x1, x2, [sp], #(2 * 16) .cfi_adjust_cfa_offset -2 * 16 ret /* return x0 = addr - tcb */ /* * Slow path * * return _rtld_tls_get_addr(tp, tlsdesc->td_tlsindex, * tlsdesc->td_tlsoffs); * */ 1: /* Save all integer registers */ stp x29, x30, [sp, #-(8 * 16)]! .cfi_adjust_cfa_offset 8 * 16 .cfi_rel_offset x29, 0 .cfi_rel_offset x30, 8 stp x5, x6, [sp, #(1 * 16)] stp x7, x8, [sp, #(2 * 16)] stp x9, x10, [sp, #(3 * 16)] stp x11, x12, [sp, #(4 * 16)] stp x13, x14, [sp, #(5 * 16)] stp x15, x16, [sp, #(6 * 16)] stp x17, x18, [sp, #(7 * 16)] .cfi_rel_offset x5, 16 .cfi_rel_offset x6, 24 .cfi_rel_offset x7, 32 .cfi_rel_offset x8, 40 .cfi_rel_offset x9, 48 .cfi_rel_offset x10, 56 .cfi_rel_offset x11, 64 .cfi_rel_offset x12, 72 .cfi_rel_offset x13, 80 .cfi_rel_offset x14, 88 .cfi_rel_offset x15, 96 .cfi_rel_offset x16, 104 .cfi_rel_offset x17, 112 .cfi_rel_offset x18, 120 /* Find the tls offset */ mov x0, x4 /* x0 := tcb */ mov x3, x1 /* x3 := tlsdesc */ ldr x1, [x3, #0] /* x1 := idx = tlsdesc->td_tlsindex */ ldr x2, [x3, #8] /* x2 := offs = tlsdesc->td_tlsoffs */ bl _rtld_tls_get_addr /* x0 := addr = _rtld_tls_get_addr(tcb, * idx, offs) */ mrs x1, tpidr_el0 /* x1 := tcb */ sub x0, x0, x1 /* x0 := addr - tcb */ /* Restore slow path registers */ ldp x17, x18, [sp, #(7 * 16)] ldp x15, x16, [sp, #(6 * 16)] ldp x13, x14, [sp, #(5 * 16)] ldp x11, x12, [sp, #(4 * 16)] ldp x9, x10, [sp, #(3 * 16)] ldp x7, x8, [sp, #(2 * 16)] ldp x5, x6, [sp, #(1 * 16)] ldp x29, x30, [sp], #(8 * 16) .cfi_adjust_cfa_offset -8 * 16 .cfi_restore x29 .cfi_restore x30 /* Restore fast path registers and return */ ldp x3, x4, [sp, #16] ldp x1, x2, [sp], #(2 * 16) .cfi_adjust_cfa_offset -2 * 16 .cfi_endproc ret /* return x0 = addr - tcb */ END(_rtld_tlsdesc_dynamic)
