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d1d7f01f7c
Mark read-only data actually read-only (simple mprotect), and to be able to test it also implement _nofault accesses. This works by setting up a new "segv_continue" pointer in current, and then when we hit a segfault we change the signal return context so that we continue at that address. The code using this sets it up so that it jumps to a label and then aborts the access that way, returning -EFAULT. It's possible to optimize the ___backtrack_faulted() thing by using asm goto (compiler version dependent) and/or gcc's (not sure if clang has it) &&label extension, but at least in one attempt I made the && caused the compiler to not load -EFAULT into the register in case of jumping to the &&label from the fault handler. So leave it like this for now. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Co-developed-by: Benjamin Berg <benjamin.berg@intel.com> Signed-off-by: Benjamin Berg <benjamin.berg@intel.com> Link: https://patch.msgid.link/20250210160926.420133-2-benjamin@sipsolutions.net Signed-off-by: Johannes Berg <johannes.berg@intel.com>
58 lines
1.5 KiB
C
58 lines
1.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#ifndef __START_H__
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#define __START_H__
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#include <generated/asm-offsets.h>
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/*
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* Stolen from linux/const.h, which can't be directly included since
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* this is used in userspace code, which has no access to the kernel
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* headers. Changed to be suitable for adding casts to the start,
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* rather than "UL" to the end.
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*/
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/* Some constant macros are used in both assembler and
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* C code. Therefore we cannot annotate them always with
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* 'UL' and other type specifiers unilaterally. We
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* use the following macros to deal with this.
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*/
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#define STUB_START stub_start
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#define STUB_CODE STUB_START
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#define STUB_DATA (STUB_CODE + UM_KERN_PAGE_SIZE)
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#define STUB_DATA_PAGES 2 /* must be a power of two */
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#define STUB_END (STUB_DATA + STUB_DATA_PAGES * UM_KERN_PAGE_SIZE)
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#ifndef __ASSEMBLY__
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#include <sysdep/ptrace.h>
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struct task_struct;
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extern struct task_struct *cpu_tasks[];
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extern unsigned long long physmem_size;
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extern unsigned long high_physmem;
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extern unsigned long uml_physmem;
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extern unsigned long uml_reserved;
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extern unsigned long end_vm;
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extern unsigned long start_vm;
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extern unsigned long brk_start;
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extern unsigned long host_task_size;
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extern unsigned long stub_start;
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extern int linux_main(int argc, char **argv, char **envp);
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extern void uml_finishsetup(void);
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struct siginfo;
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extern void (*sig_info[])(int, struct siginfo *si, struct uml_pt_regs *, void *);
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#endif
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#endif
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