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/* Copyright 2002,2003 Andi Kleen, SuSE Labs */
/* vsyscall handling for 32bit processes. Map a stub page into it
on demand because 32bit cannot reach the kernel's fixmaps */
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/stringify.h>
#include <linux/security.h>
#include <asm/proto.h>
#include <asm/tlbflush.h>
#include <asm/ia32_unistd.h>
/* 32bit VDSOs mapped into user space. */
asm(".section \".init.data\",\"aw\"\n"
"syscall32_syscall:\n"
".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n"
"syscall32_syscall_end:\n"
"syscall32_sysenter:\n"
".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n"
"syscall32_sysenter_end:\n"
".previous");
extern unsigned char syscall32_syscall[], syscall32_syscall_end[];
extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[];
extern int sysctl_vsyscall32;
char *syscall32_page;
static int use_sysenter = -1;
static struct page *
syscall32_nopage(struct vm_area_struct *vma, unsigned long adr, int *type)
{
struct page *p = virt_to_page(adr - vma->vm_start + syscall32_page);
get_page(p);
return p;
}
/* Prevent VMA merging */
static void syscall32_vma_close(struct vm_area_struct *vma)
{
}
static struct vm_operations_struct syscall32_vm_ops = {
.close = syscall32_vma_close,
.nopage = syscall32_nopage,
};
struct linux_binprm;
/* Setup a VMA at program startup for the vsyscall page */
int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
{
int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
struct vm_area_struct *vma;
struct mm_struct *mm = current->mm;
int ret;
vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
if (!vma)
return -ENOMEM;
if (security_vm_enough_memory(npages)) {
kmem_cache_free(vm_area_cachep, vma);
return -ENOMEM;
}
memset(vma, 0, sizeof(struct vm_area_struct));
/* Could randomize here */
vma->vm_start = VSYSCALL32_BASE;
vma->vm_end = VSYSCALL32_END;
/* MAYWRITE to allow gdb to COW and set breakpoints */
vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYEXEC|VM_MAYWRITE;
vma->vm_flags |= mm->def_flags;
vma->vm_page_prot = protection_map[vma->vm_flags & 7];
vma->vm_ops = &syscall32_vm_ops;
vma->vm_mm = mm;
down_write(&mm->mmap_sem);
if ((ret = insert_vm_struct(mm, vma))) {
up_write(&mm->mmap_sem);
kmem_cache_free(vm_area_cachep, vma);
return ret;
}
mm->total_vm += npages;
up_write(&mm->mmap_sem);
return 0;
}
static int __init init_syscall32(void)
{
syscall32_page = (void *)get_zeroed_page(GFP_KERNEL);
if (!syscall32_page)
panic("Cannot allocate syscall32 page");
if (use_sysenter > 0) {
memcpy(syscall32_page, syscall32_sysenter,
syscall32_sysenter_end - syscall32_sysenter);
} else {
memcpy(syscall32_page, syscall32_syscall,
syscall32_syscall_end - syscall32_syscall);
}
return 0;
}
__initcall(init_syscall32);
/* May not be __init: called during resume */
void syscall32_cpu_init(void)
{
if (use_sysenter < 0)
use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL);
/* Load these always in case some future AMD CPU supports
SYSENTER from compat mode too. */
checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL);
checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
wrmsrl(MSR_CSTAR, ia32_cstar_target);
}
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