65 lines
1.6 KiB
ArmAsm
65 lines
1.6 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2019 ARM Limited */
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#include <asm/unistd.h>
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.section .rodata, "a"
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call_fmt:
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.asciz "Calling sigreturn with fake sigframe sized:%zd at SP @%08lX\n"
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.text
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.globl fake_sigreturn
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/* fake_sigreturn x0:&sigframe, x1:sigframe_size, x2:misalign_bytes */
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fake_sigreturn:
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stp x29, x30, [sp, #-16]!
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mov x29, sp
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mov x20, x0
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mov x21, x1
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mov x22, x2
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/* create space on the stack for fake sigframe 16 bytes-aligned */
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add x0, x21, x22
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add x0, x0, #15
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bic x0, x0, #15 /* round_up(sigframe_size + misalign_bytes, 16) */
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sub sp, sp, x0
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add x23, sp, x22 /* new sigframe base with misaligment if any */
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ldr x0, =call_fmt
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mov x1, x21
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mov x2, x23
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bl printf
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/* memcpy the provided content, while still keeping SP aligned */
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mov x0, x23
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mov x1, x20
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mov x2, x21
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bl memcpy
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/*
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* Here saving a last minute SP to current->token acts as a marker:
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* if we got here, we are successfully faking a sigreturn; in other
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* words we are sure no bad fatal signal has been raised till now
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* for unrelated reasons, so we should consider the possibly observed
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* fatal signal like SEGV coming from Kernel restore_sigframe() and
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* triggered as expected from our test-case.
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* For simplicity this assumes that current field 'token' is laid out
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* as first in struct tdescr
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*/
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ldr x0, current
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str x23, [x0]
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/* finally move SP to misaligned address...if any requested */
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mov sp, x23
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mov x8, #__NR_rt_sigreturn
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svc #0
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/*
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* Above sigreturn should not return...looping here leads to a timeout
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* and ensure proper and clean test failure, instead of jumping around
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* on a potentially corrupted stack.
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*/
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b .
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