91 lines
2.6 KiB
C
91 lines
2.6 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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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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static struct page *syscall32_pages[1];
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static int use_sysenter = -1;
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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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struct mm_struct *mm = current->mm;
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int ret;
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down_write(&mm->mmap_sem);
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/*
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* MAYWRITE to allow gdb to COW and set breakpoints
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*
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* Make sure the vDSO gets into every core dump.
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* Dumping its contents makes post-mortem fully interpretable later
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* without matching up the same kernel and hardware config to see
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* what PC values meant.
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*/
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/* Could randomize here */
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ret = install_special_mapping(mm, VSYSCALL32_BASE, PAGE_SIZE,
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VM_READ|VM_EXEC|
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VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
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VM_ALWAYSDUMP,
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syscall32_pages);
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up_write(&mm->mmap_sem);
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return ret;
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}
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const char *arch_vma_name(struct vm_area_struct *vma)
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{
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if (vma->vm_start == VSYSCALL32_BASE &&
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vma->vm_mm && vma->vm_mm->task_size == IA32_PAGE_OFFSET)
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return "[vdso]";
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return NULL;
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}
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static int __init init_syscall32(void)
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{
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char *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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syscall32_pages[0] = virt_to_page(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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