1/* Copyright 2002,2003 Andi Kleen, SuSE Labs */ 2 3/* vsyscall handling for 32bit processes. Map a stub page into it 4 on demand because 32bit cannot reach the kernel's fixmaps */ 5 6#include <linux/mm.h> 7#include <linux/string.h> 8#include <linux/kernel.h> 9#include <linux/gfp.h> 10#include <linux/init.h> 11#include <linux/stringify.h> 12#include <linux/security.h> 13#include <asm/proto.h> 14#include <asm/tlbflush.h> 15#include <asm/ia32_unistd.h> 16#include <asm/vsyscall32.h> 17 18extern unsigned char syscall32_syscall[], syscall32_syscall_end[]; 19extern unsigned char syscall32_sysenter[], syscall32_sysenter_end[]; 20extern int sysctl_vsyscall32; 21 22static struct page *syscall32_pages[1]; 23static int use_sysenter = -1; 24 25struct linux_binprm; 26 27/* Setup a VMA at program startup for the vsyscall page */ 28int syscall32_setup_pages(struct linux_binprm *bprm, int exstack) 29{ 30 struct mm_struct *mm = current->mm; 31 int ret; 32 33 down_write(&mm->mmap_sem); 34 /* 35 * MAYWRITE to allow gdb to COW and set breakpoints 36 * 37 * Make sure the vDSO gets into every core dump. 38 * Dumping its contents makes post-mortem fully interpretable later 39 * without matching up the same kernel and hardware config to see 40 * what PC values meant. 41 */ 42 /* Could randomize here */ 43 ret = install_special_mapping(mm, VSYSCALL32_BASE, PAGE_SIZE, 44 VM_READ|VM_EXEC| 45 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC| 46 VM_ALWAYSDUMP, 47 syscall32_pages); 48 up_write(&mm->mmap_sem); 49 return ret; 50} 51 52const char *arch_vma_name(struct vm_area_struct *vma) 53{ 54 if (vma->vm_start == VSYSCALL32_BASE && 55 vma->vm_mm && vma->vm_mm->task_size == IA32_PAGE_OFFSET) 56 return "[vdso]"; 57 return NULL; 58} 59 60static int __init init_syscall32(void) 61{ 62 char *syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); 63 if (!syscall32_page) 64 panic("Cannot allocate syscall32 page"); 65 syscall32_pages[0] = virt_to_page(syscall32_page); 66 if (use_sysenter > 0) { 67 memcpy(syscall32_page, syscall32_sysenter, 68 syscall32_sysenter_end - syscall32_sysenter); 69 } else { 70 memcpy(syscall32_page, syscall32_syscall, 71 syscall32_syscall_end - syscall32_syscall); 72 } 73 return 0; 74} 75 76__initcall(init_syscall32); 77 78/* May not be __init: called during resume */ 79void syscall32_cpu_init(void) 80{ 81 if (use_sysenter < 0) 82 use_sysenter = (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL); 83 84 /* Load these always in case some future AMD CPU supports 85 SYSENTER from compat mode too. */ 86 checking_wrmsrl(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS); 87 checking_wrmsrl(MSR_IA32_SYSENTER_ESP, 0ULL); 88 checking_wrmsrl(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target); 89 90 wrmsrl(MSR_CSTAR, ia32_cstar_target); 91} 92