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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
*/
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <asm/pgalloc.h>
#include <asm/sections.h>
#include <asm/mmu_context.h>
#include <as-layout.h>
#include <os.h>
#include <skas.h>
#include <stub-data.h>
/* Ensure the stub_data struct covers the allocated area */
static_assert(sizeof(struct stub_data) == STUB_DATA_PAGES * UM_KERN_PAGE_SIZE);
int init_new_context(struct task_struct *task, struct mm_struct *mm)
{
struct mm_context *from_mm = NULL;
struct mm_context *to_mm = &mm->context;
unsigned long stack = 0;
int ret = -ENOMEM;
stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES));
if (stack == 0)
goto out;
to_mm->id.stack = stack;
if (current->mm != NULL && current->mm != &init_mm)
from_mm = ¤t->mm->context;
block_signals_trace();
if (from_mm)
to_mm->id.u.pid = copy_context_skas0(stack,
from_mm->id.u.pid);
else to_mm->id.u.pid = start_userspace(stack);
unblock_signals_trace();
if (to_mm->id.u.pid < 0) {
ret = to_mm->id.u.pid;
goto out_free;
}
ret = init_new_ldt(to_mm, from_mm);
if (ret < 0) {
printk(KERN_ERR "init_new_context_skas - init_ldt"
" failed, errno = %d\n", ret);
goto out_free;
}
return 0;
out_free:
if (to_mm->id.stack != 0)
free_pages(to_mm->id.stack, ilog2(STUB_DATA_PAGES));
out:
return ret;
}
void destroy_context(struct mm_struct *mm)
{
struct mm_context *mmu = &mm->context;
/*
* If init_new_context wasn't called, this will be
* zero, resulting in a kill(0), which will result in the
* whole UML suddenly dying. Also, cover negative and
* 1 cases, since they shouldn't happen either.
*/
if (mmu->id.u.pid < 2) {
printk(KERN_ERR "corrupt mm_context - pid = %d\n",
mmu->id.u.pid);
return;
}
os_kill_ptraced_process(mmu->id.u.pid, 1);
free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES));
free_ldt(mmu);
}
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