65 lines · plain
1/* SPDX-License-Identifier: GPL-2.0 */2/* Copyright (C) 2019 ARM Limited */3 4#include <asm/unistd.h>5 6.section .rodata, "a"7call_fmt:8 .asciz "Calling sigreturn with fake sigframe sized:%zd at SP @%08lX\n"9 10.text11 12.globl fake_sigreturn13 14/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */15fake_sigreturn:16 stp x29, x30, [sp, #-16]!17 mov x29, sp18 19 mov x20, x020 mov x21, x121 mov x22, x222 23 /* create space on the stack for fake sigframe 16 bytes-aligned */24 add x0, x21, x2225 add x0, x0, #1526 bic x0, x0, #15 /* round_up(sigframe_size + misalign_bytes, 16) */27 sub sp, sp, x028 add x23, sp, x22 /* new sigframe base with misaligment if any */29 30 ldr x0, =call_fmt31 mov x1, x2132 mov x2, x2333 bl printf34 35 /* memcpy the provided content, while still keeping SP aligned */36 mov x0, x2337 mov x1, x2038 mov x2, x2139 bl memcpy40 41 /*42 * Here saving a last minute SP to current->token acts as a marker:43 * if we got here, we are successfully faking a sigreturn; in other44 * words we are sure no bad fatal signal has been raised till now45 * for unrelated reasons, so we should consider the possibly observed46 * fatal signal like SEGV coming from Kernel restore_sigframe() and47 * triggered as expected from our test-case.48 * For simplicity this assumes that current field 'token' is laid out49 * as first in struct tdescr50 */51 ldr x0, current52 str x23, [x0]53 /* finally move SP to misaligned address...if any requested */54 mov sp, x2355 56 mov x8, #__NR_rt_sigreturn57 svc #058 59 /*60 * Above sigreturn should not return...looping here leads to a timeout61 * and ensure proper and clean test failure, instead of jumping around62 * on a potentially corrupted stack.63 */64 b .65