cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mmu.c (1789B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
      4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
      5 */
      6
      7#include <linux/mm.h>
      8#include <linux/sched/signal.h>
      9#include <linux/slab.h>
     10
     11#include <asm/pgalloc.h>
     12#include <asm/sections.h>
     13#include <as-layout.h>
     14#include <os.h>
     15#include <skas.h>
     16
     17int init_new_context(struct task_struct *task, struct mm_struct *mm)
     18{
     19 	struct mm_context *from_mm = NULL;
     20	struct mm_context *to_mm = &mm->context;
     21	unsigned long stack = 0;
     22	int ret = -ENOMEM;
     23
     24	stack = get_zeroed_page(GFP_KERNEL);
     25	if (stack == 0)
     26		goto out;
     27
     28	to_mm->id.stack = stack;
     29	if (current->mm != NULL && current->mm != &init_mm)
     30		from_mm = &current->mm->context;
     31
     32	block_signals_trace();
     33	if (from_mm)
     34		to_mm->id.u.pid = copy_context_skas0(stack,
     35						     from_mm->id.u.pid);
     36	else to_mm->id.u.pid = start_userspace(stack);
     37	unblock_signals_trace();
     38
     39	if (to_mm->id.u.pid < 0) {
     40		ret = to_mm->id.u.pid;
     41		goto out_free;
     42	}
     43
     44	ret = init_new_ldt(to_mm, from_mm);
     45	if (ret < 0) {
     46		printk(KERN_ERR "init_new_context_skas - init_ldt"
     47		       " failed, errno = %d\n", ret);
     48		goto out_free;
     49	}
     50
     51	return 0;
     52
     53 out_free:
     54	if (to_mm->id.stack != 0)
     55		free_page(to_mm->id.stack);
     56 out:
     57	return ret;
     58}
     59
     60void destroy_context(struct mm_struct *mm)
     61{
     62	struct mm_context *mmu = &mm->context;
     63
     64	/*
     65	 * If init_new_context wasn't called, this will be
     66	 * zero, resulting in a kill(0), which will result in the
     67	 * whole UML suddenly dying.  Also, cover negative and
     68	 * 1 cases, since they shouldn't happen either.
     69	 */
     70	if (mmu->id.u.pid < 2) {
     71		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
     72		       mmu->id.u.pid);
     73		return;
     74	}
     75	os_kill_ptraced_process(mmu->id.u.pid, 1);
     76
     77	free_page(mmu->id.stack);
     78	free_ldt(mmu);
     79}