freebsd-nq/libexec/rtld-elf/riscv/rtld_start.S
Brooks Davis 29e1fceb73 Maintain a stack alignment of 16-bytes.
This violated the RISC-V 64-bit ABI.  On CheriBSD this manifested as
a trap when attempting to store 16-byte aligned types while zeroing
the stack.

Reported by:	CHERI, jrtc27
Reviewed by:	mhorne, br
Obtained from:	CheriBSD
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D26327
2020-09-04 21:46:10 +00:00

131 lines
3.8 KiB
ArmAsm

/*-
* Copyright (c) 2015-2018 Ruslan Bukin <br@bsdpad.com>
* All rights reserved.
*
* This software was developed by SRI International and the University of
* Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
* ("CTSRD"), as part of the DARPA CRASH research programme.
*
* This software was developed by the University of Cambridge Computer
* Laboratory as part of the CTSRD Project, with support from the UK Higher
* Education Innovation Fund (HEIF).
*
* 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>
__FBSDID("$FreeBSD$");
/*
* func_ptr_type
* _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
*/
ENTRY(.rtld_start)
mv s0, a0 /* Put ps_strings in a callee-saved register */
mv s1, sp /* And the stack pointer */
addi sp, sp, -16 /* Make room for obj_main & exit proc */
mv a1, sp /* exit_proc */
addi a2, a1, 8 /* obj_main */
jal _rtld /* Call the loader */
mv t0, a0 /* Backup the entry point */
ld a2, 0(sp) /* Load cleanup */
ld a1, 8(sp) /* Load obj_main */
mv a0, s0 /* Restore ps_strings */
mv sp, s1 /* Restore the stack pointer */
jr t0 /* Jump to the entry point */
END(.rtld_start)
/*
* t0 = obj pointer
* t1 = reloc offset
*/
ENTRY(_rtld_bind_start)
/* Save the arguments and ra */
/* We require 17 dwords, but the stack must be aligned to 16-bytes */
addi sp, sp, -(8 * 18)
sd a0, (8 * 0)(sp)
sd a1, (8 * 1)(sp)
sd a2, (8 * 2)(sp)
sd a3, (8 * 3)(sp)
sd a4, (8 * 4)(sp)
sd a5, (8 * 5)(sp)
sd a6, (8 * 6)(sp)
sd a7, (8 * 7)(sp)
sd ra, (8 * 8)(sp)
#ifdef __riscv_float_abi_double
/* Save any floating-point arguments */
fsd fa0, (8 * 9)(sp)
fsd fa1, (8 * 10)(sp)
fsd fa2, (8 * 11)(sp)
fsd fa3, (8 * 12)(sp)
fsd fa4, (8 * 13)(sp)
fsd fa5, (8 * 14)(sp)
fsd fa6, (8 * 15)(sp)
fsd fa7, (8 * 16)(sp)
#endif
/* Reloc offset is 3x of the .got.plt offset */
slli a1, t1, 1 /* Mult items by 2 */
add a1, a1, t1 /* Plus item */
/* Load obj */
mv a0, t0
/* Call into rtld */
jal _rtld_bind
/* Backup the address to branch to */
mv t0, a0
/* Restore the arguments and ra */
ld a0, (8 * 0)(sp)
ld a1, (8 * 1)(sp)
ld a2, (8 * 2)(sp)
ld a3, (8 * 3)(sp)
ld a4, (8 * 4)(sp)
ld a5, (8 * 5)(sp)
ld a6, (8 * 6)(sp)
ld a7, (8 * 7)(sp)
ld ra, (8 * 8)(sp)
#ifdef __riscv_float_abi_double
/* Restore floating-point arguments */
fld fa0, (8 * 9)(sp)
fld fa1, (8 * 10)(sp)
fld fa2, (8 * 11)(sp)
fld fa3, (8 * 12)(sp)
fld fa4, (8 * 13)(sp)
fld fa5, (8 * 14)(sp)
fld fa6, (8 * 15)(sp)
fld fa7, (8 * 16)(sp)
#endif
addi sp, sp, (8 * 18)
/* Call into the correct function */
jr t0
END(_rtld_bind_start)