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Diffstat (limited to 'arch/um/sys-x86_64/syscalls.c')
-rw-r--r--arch/um/sys-x86_64/syscalls.c75
1 files changed, 57 insertions, 18 deletions
diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c
index 73ce4463f70..01b91f9fa78 100644
--- a/arch/um/sys-x86_64/syscalls.c
+++ b/arch/um/sys-x86_64/syscalls.c
@@ -16,6 +16,7 @@
#include "asm/prctl.h" /* XXX This should get the constants from libc */
#include "choose-mode.h"
#include "kern.h"
+#include "os.h"
asmlinkage long sys_uname64(struct new_utsname __user * name)
{
@@ -58,40 +59,69 @@ static long arch_prctl_tt(int code, unsigned long addr)
#ifdef CONFIG_MODE_SKAS
-/* XXX: Must also call arch_prctl in the host, beside saving the segment bases! */
-static long arch_prctl_skas(int code, unsigned long addr)
+long arch_prctl_skas(struct task_struct *task, int code,
+ unsigned long __user *addr)
{
- long ret = 0;
+ unsigned long *ptr = addr, tmp;
+ long ret;
+ int pid = task->mm->context.skas.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:
- current->thread.regs.regs.skas.regs[FS_BASE / sizeof(unsigned long)] = addr;
- break;
case ARCH_SET_GS:
- current->thread.regs.regs.skas.regs[GS_BASE / sizeof(unsigned long)] = addr;
+ restore_registers(pid, &current->thread.regs.regs);
+ 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:
+ case ARCH_SET_GS:
+ save_registers(pid, &current->thread.regs.regs);
break;
case ARCH_GET_FS:
- ret = put_user(current->thread.regs.regs.skas.
- regs[FS_BASE / sizeof(unsigned long)],
- (unsigned long __user *)addr);
+ ret = put_user(tmp, addr);
break;
case ARCH_GET_GS:
- ret = put_user(current->thread.regs.regs.skas.
- regs[GS_BASE / sizeof(unsigned long)],
- (unsigned long __user *)addr);
+ ret = put_user(tmp, addr);
break;
- default:
- ret = -EINVAL;
- break;
}
- return(ret);
+ return ret;
}
#endif
long sys_arch_prctl(int code, unsigned long addr)
{
- return(CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code, addr));
+ return CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, current, code,
+ (unsigned long __user *) addr);
}
long sys_clone(unsigned long clone_flags, unsigned long newsp,
@@ -105,5 +135,14 @@ long sys_clone(unsigned long clone_flags, unsigned long newsp,
ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
child_tid);
current->thread.forking = 0;
- return(ret);
+ return ret;
+}
+
+void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
+{
+ if(to->thread.arch.fs == 0)
+ return;
+
+ arch_prctl_skas(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
}
+