forked from luck/tmp_suning_uos_patched
1e01441051
Use a real VMA to map the 32bit vsyscall page This interacts better with Hugh's upcomming VMA walk optimization Also removes some ugly special cases. Code roughly modelled after the ppc64 vdso version from Ben Herrenschmidt. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
118 lines
3.3 KiB
C
118 lines
3.3 KiB
C
/* Copyright 2002,2003 Andi Kleen, SuSE Labs */
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/* vsyscall handling for 32bit processes. Map a stub page into it
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on demand because 32bit cannot reach the kernel's fixmaps */
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/init.h>
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#include <linux/stringify.h>
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#include <linux/security.h>
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#include <asm/proto.h>
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#include <asm/tlbflush.h>
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#include <asm/ia32_unistd.h>
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/* 32bit VDSOs mapped into user space. */
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asm(".section \".init.data\",\"aw\"\n"
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"syscall32_syscall:\n"
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".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n"
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"syscall32_syscall_end:\n"
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"syscall32_sysenter:\n"
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".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n"
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"syscall32_sysenter_end:\n"
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".previous");
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extern unsigned char syscall32_syscall[], syscall32_syscall_end[];
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extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[];
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extern int sysctl_vsyscall32;
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char *syscall32_page;
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static int use_sysenter = -1;
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static struct page *
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syscall32_nopage(struct vm_area_struct *vma, unsigned long adr, int *type)
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{
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struct page *p = virt_to_page(adr - vma->vm_start + syscall32_page);
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get_page(p);
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return p;
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}
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/* Prevent VMA merging */
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static void syscall32_vma_close(struct vm_area_struct *vma)
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{
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}
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static struct vm_operations_struct syscall32_vm_ops = {
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.close = syscall32_vma_close,
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.nopage = syscall32_nopage,
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};
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struct linux_binprm;
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/* Setup a VMA at program startup for the vsyscall page */
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int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
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{
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int npages = (VSYSCALL32_END - VSYSCALL32_BASE) >> PAGE_SHIFT;
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struct vm_area_struct *vma;
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struct mm_struct *mm = current->mm;
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vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
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if (!vma)
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return -ENOMEM;
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if (security_vm_enough_memory(npages)) {
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kmem_cache_free(vm_area_cachep, vma);
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return -ENOMEM;
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}
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memset(vma, 0, sizeof(struct vm_area_struct));
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/* Could randomize here */
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vma->vm_start = VSYSCALL32_BASE;
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vma->vm_end = VSYSCALL32_END;
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/* MAYWRITE to allow gdb to COW and set breakpoints */
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vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYEXEC|VM_MAYWRITE;
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vma->vm_flags |= mm->def_flags;
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vma->vm_page_prot = protection_map[vma->vm_flags & 7];
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vma->vm_ops = &syscall32_vm_ops;
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vma->vm_mm = mm;
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down_write(&mm->mmap_sem);
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insert_vm_struct(mm, vma);
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mm->total_vm += npages;
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up_write(&mm->mmap_sem);
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return 0;
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}
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static int __init init_syscall32(void)
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{
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syscall32_page = (void *)get_zeroed_page(GFP_KERNEL);
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if (!syscall32_page)
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panic("Cannot allocate syscall32 page");
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if (use_sysenter > 0) {
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memcpy(syscall32_page, syscall32_sysenter,
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syscall32_sysenter_end - syscall32_sysenter);
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} else {
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memcpy(syscall32_page, syscall32_syscall,
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syscall32_syscall_end - syscall32_syscall);
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}
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return 0;
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}
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__initcall(init_syscall32);
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/* May not be __init: called during resume */
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void syscall32_cpu_init(void)
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{
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if (use_sysenter < 0)
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use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL);
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/* Load these always in case some future AMD CPU supports
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SYSENTER from compat mode too. */
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checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
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checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL);
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checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
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wrmsrl(MSR_CSTAR, ia32_cstar_target);
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}
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