/* 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> 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, GFP_KERNEL); if (!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_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); }