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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/um/syscalls_64.c
Initial import
Diffstat (limited to 'arch/x86/um/syscalls_64.c')
-rw-r--r--arch/x86/um/syscalls_64.c85
1 files changed, 85 insertions, 0 deletions
diff --git a/arch/x86/um/syscalls_64.c b/arch/x86/um/syscalls_64.c
new file mode 100644
index 000000000..adb08eb5c
--- /dev/null
+++ b/arch/x86/um/syscalls_64.c
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright 2003 PathScale, Inc.
+ *
+ * Licensed under the GPL
+ */
+
+#include <linux/sched.h>
+#include <asm/prctl.h> /* XXX This should get the constants from libc */
+#include <os.h>
+
+long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
+{
+ unsigned long *ptr = addr, tmp;
+ long ret;
+ int pid = task->mm->context.id.u.pid;
+
+ /*
+ * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
+ * be safe), we need to call arch_prctl on the host because
+ * setting %fs may result in something else happening (like a
+ * GDT or thread.fs being set instead). So, we let the host
+ * fiddle the registers and thread struct and restore the
+ * registers afterwards.
+ *
+ * So, the saved registers are stored to the process (this
+ * needed because a stub may have been the last thing to run),
+ * arch_prctl is run on the host, then the registers are read
+ * back.
+ */
+ switch (code) {
+ case ARCH_SET_FS:
+ case ARCH_SET_GS:
+ ret = restore_registers(pid, &current->thread.regs.regs);
+ if (ret)
+ return ret;
+ break;
+ case ARCH_GET_FS:
+ case ARCH_GET_GS:
+ /*
+ * With these two, we read to a local pointer and
+ * put_user it to the userspace pointer that we were
+ * given. If addr isn't valid (because it hasn't been
+ * faulted in or is just bogus), we want put_user to
+ * fault it in (or return -EFAULT) instead of having
+ * the host return -EFAULT.
+ */
+ ptr = &tmp;
+ }
+
+ ret = os_arch_prctl(pid, code, ptr);
+ if (ret)
+ return ret;
+
+ switch (code) {
+ case ARCH_SET_FS:
+ current->thread.arch.fs = (unsigned long) ptr;
+ ret = save_registers(pid, &current->thread.regs.regs);
+ break;
+ case ARCH_SET_GS:
+ ret = save_registers(pid, &current->thread.regs.regs);
+ break;
+ case ARCH_GET_FS:
+ ret = put_user(tmp, addr);
+ break;
+ case ARCH_GET_GS:
+ ret = put_user(tmp, addr);
+ break;
+ }
+
+ return ret;
+}
+
+long sys_arch_prctl(int code, unsigned long addr)
+{
+ return arch_prctl(current, code, (unsigned long __user *) addr);
+}
+
+void arch_switch_to(struct task_struct *to)
+{
+ if ((to->thread.arch.fs == 0) || (to->mm == NULL))
+ return;
+
+ arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
+}