1 files changed, 111 insertions, 0 deletions

diff --git a/arch/x86_64/ia32/syscall32.c b/arch/x86_64/ia32/syscall32.c
new file mode 100644
index 000000000000..399ff4985099
--- /dev/null
+++ b/arch/x86_64/ia32/syscall32.c
@@ -0,0 +1,111 @@
+/* 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);
+}