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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 <as-layout.h>
#include <os.h>
#include <skas.h>
static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
unsigned long kernel)
{
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pgd = pgd_offset(mm, proc);
p4d = p4d_alloc(mm, pgd, proc);
if (!p4d)
goto out;
pud = pud_alloc(mm, p4d, proc);
if (!pud)
goto out_pud;
pmd = pmd_alloc(mm, pud, proc);
if (!pmd)
goto out_pmd;
pte = pte_alloc_map(mm, pmd, proc);
if (!pte)
goto out_pte;
*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
*pte = pte_mkread(*pte);
return 0;
out_pte:
pmd_free(mm, pmd);
out_pmd:
pud_free(mm, pud);
out_pud:
p4d_free(mm, p4d);
out:
return -ENOMEM;
}
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_zeroed_page(GFP_KERNEL);
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_page(to_mm->id.stack);
out:
return ret;
}
void uml_setup_stubs(struct mm_struct *mm)
{
int err, ret;
ret = init_stub_pte(mm, STUB_CODE,
(unsigned long) __syscall_stub_start);
if (ret)
goto out;
ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
if (ret)
goto out;
mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
/* dup_mmap already holds mmap_lock */
err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
VM_READ | VM_MAYREAD | VM_EXEC |
VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
mm->context.stub_pages);
if (err) {
printk(KERN_ERR "install_special_mapping returned %d\n", err);
goto out;
}
return;
out:
force_sigsegv(SIGSEGV);
}
void arch_exit_mmap(struct mm_struct *mm)
{
pte_t *pte;
pte = virt_to_pte(mm, STUB_CODE);
if (pte != NULL)
pte_clear(mm, STUB_CODE, pte);
pte = virt_to_pte(mm, STUB_DATA);
if (pte == NULL)
return;
pte_clear(mm, STUB_DATA, pte);
}
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_page(mmu->id.stack);
free_ldt(mmu);
}
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