/* 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> #include <asm/vsyscall32.h> extern unsigned char syscall32_syscall[], syscall32_syscall_end[]; extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[]; extern int sysctl_vsyscall32; static struct page *syscall32_pages[1]; static int use_sysenter = -1; struct linux_binprm; /* Setup a VMA at program startup for the vsyscall page */ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack) { struct mm_struct *mm = current->mm; int ret; down_write(&mm->mmap_sem); /* * MAYWRITE to allow gdb to COW and set breakpoints * * Make sure the vDSO gets into every core dump. * Dumping its contents makes post-mortem fully interpretable later * without matching up the same kernel and hardware config to see * what PC values meant. */ /* Could randomize here */ ret = install_special_mapping(mm, VSYSCALL32_BASE, PAGE_SIZE, VM_READ|VM_EXEC| VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| VM_ALWAYSDUMP, syscall32_pages); up_write(&mm->mmap_sem); return ret; } const char *arch_vma_name(struct vm_area_struct *vma) { if (vma->vm_start == VSYSCALL32_BASE && vma->vm_mm && vma->vm_mm->task_size == IA32_PAGE_OFFSET) return "[vdso]"; return NULL; } static int __init init_syscall32(void) { char *syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); if (!syscall32_page) panic("Cannot allocate syscall32 page"); syscall32_pages[0] = virt_to_page(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); }