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- /* 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;
- }
- 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);
- }
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