| /* 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 <asm/proto.h> |
| #include <asm/tlbflush.h> |
| #include <asm/ia32_unistd.h> |
| |
| /* 32bit VDSOs mapped into user space. */ |
| asm(".section \".init.data\",\"aw\"\n" |
| "syscall32_syscall:\n" |
| ".incbin \"arch/x86_64/ia32/vsyscall-syscall.so\"\n" |
| "syscall32_syscall_end:\n" |
| "syscall32_sysenter:\n" |
| ".incbin \"arch/x86_64/ia32/vsyscall-sysenter.so\"\n" |
| "syscall32_sysenter_end:\n" |
| ".previous"); |
| |
| 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; |
| |
| /* |
| * Map the 32bit vsyscall page on demand. |
| * |
| * RED-PEN: This knows too much about high level VM. |
| * |
| * Alternative would be to generate a vma with appropriate backing options |
| * and let it be handled by generic VM. |
| */ |
| int __map_syscall32(struct mm_struct *mm, unsigned long address) |
| { |
| pgd_t *pgd; |
| pud_t *pud; |
| pte_t *pte; |
| pmd_t *pmd; |
| int err = -ENOMEM; |
| |
| spin_lock(&mm->page_table_lock); |
| pgd = pgd_offset(mm, address); |
| pud = pud_alloc(mm, pgd, address); |
| if (pud) { |
| pmd = pmd_alloc(mm, pud, address); |
| if (pmd && (pte = pte_alloc_map(mm, pmd, address)) != NULL) { |
| if (pte_none(*pte)) { |
| set_pte(pte, |
| mk_pte(virt_to_page(syscall32_page), |
| PAGE_KERNEL_VSYSCALL32)); |
| } |
| /* Flush only the local CPU. Other CPUs taking a fault |
| will just end up here again |
| This probably not needed and just paranoia. */ |
| __flush_tlb_one(address); |
| err = 0; |
| } |
| } |
| spin_unlock(&mm->page_table_lock); |
| return err; |
| } |
| |
| int map_syscall32(struct mm_struct *mm, unsigned long address) |
| { |
| int err; |
| down_read(&mm->mmap_sem); |
| err = __map_syscall32(mm, address); |
| up_read(&mm->mmap_sem); |
| return err; |
| } |
| |
| static int __init init_syscall32(void) |
| { |
| syscall32_page = (void *)get_zeroed_page(GFP_KERNEL); |
| if (!syscall32_page) |
| panic("Cannot allocate syscall32 page"); |
| SetPageReserved(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); |
| } |