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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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