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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>
91 lines
1.8 KiB
C
91 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#ifndef __UM_PROCESSOR_GENERIC_H
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#define __UM_PROCESSOR_GENERIC_H
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struct pt_regs;
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struct task_struct;
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#include <asm/ptrace.h>
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#include <sysdep/archsetjmp.h>
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#include <linux/prefetch.h>
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#include <asm/cpufeatures.h>
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struct mm_struct;
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struct thread_struct {
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struct pt_regs *segv_regs;
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struct task_struct *prev_sched;
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struct arch_thread arch;
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jmp_buf switch_buf;
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struct {
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struct {
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int (*proc)(void *);
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void *arg;
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} thread;
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} request;
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void *segv_continue;
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/* Contains variable sized FP registers */
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struct pt_regs regs;
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};
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#define INIT_THREAD \
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{ \
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.regs = EMPTY_REGS, \
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.prev_sched = NULL, \
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.arch = INIT_ARCH_THREAD, \
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.request = { } \
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}
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/*
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* User space process size: 3GB (default).
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*/
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extern unsigned long task_size;
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#define TASK_SIZE (task_size)
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#undef STACK_TOP
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#undef STACK_TOP_MAX
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extern unsigned long stacksizelim;
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#define STACK_ROOM (stacksizelim)
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#define STACK_TOP (TASK_SIZE - 2 * PAGE_SIZE)
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#define STACK_TOP_MAX STACK_TOP
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/* This decides where the kernel will search for a free chunk of vm
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* space during mmap's.
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*/
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#define TASK_UNMAPPED_BASE (0x40000000)
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extern void start_thread(struct pt_regs *regs, unsigned long entry,
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unsigned long stack);
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struct cpuinfo_um {
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unsigned long loops_per_jiffy;
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int ipi_pipe[2];
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int cache_alignment;
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union {
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__u32 x86_capability[NCAPINTS + NBUGINTS];
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unsigned long x86_capability_alignment;
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};
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};
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extern struct cpuinfo_um boot_cpu_data;
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#define cpu_data(cpu) boot_cpu_data
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#define current_cpu_data boot_cpu_data
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#define cache_line_size() (boot_cpu_data.cache_alignment)
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#define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
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extern unsigned long __get_wchan(struct task_struct *p);
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#endif
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