1 files changed, 83 insertions, 0 deletions

diff --git a/arch/x86/ia32/syscall32.c b/arch/x86/ia32/syscall32.c
new file mode 100644
index 000000000000..15013bac181c
--- /dev/null
+++ b/arch/x86/ia32/syscall32.c
@@ -0,0 +1,83 @@
+/* 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);
+}