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Diffstat (limited to 'arch/x86/ia32/syscall32.c')
-rw-r--r--arch/x86/ia32/syscall32.c83
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);
+}