x86: x86-32 ptrace get/putreg current task

This generalizes the getreg and putreg functions so they can be used on the
current task, as well as on a task stopped in TASK_TRACED and switched off.
This lays the groundwork to share this code for all kinds of user-mode
machine state access, not just ptrace.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/kernel/ptrace_32.c b/arch/x86/kernel/ptrace_32.c
index 5aca84ef26d..26071305de2 100644
--- a/arch/x86/kernel/ptrace_32.c
+++ b/arch/x86/kernel/ptrace_32.c
@@ -55,6 +55,12 @@ static int putreg(struct task_struct *child,
                 if (value && (value & 3) != 3)
                         return -EIO;
                 child->thread.gs = value;
+                if (child == current)
+                        /*
+                         * The user-mode %gs is not affected by
+                         * kernel entry, so we must update the CPU.
+                         */
+                        loadsegment(gs, value);
                 return 0;
         case DS:
         case ES:
@@ -104,6 +110,8 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
                 break;
         case GS:
                 retval = child->thread.gs;
+                if (child == current)
+                        savesegment(gs, retval);
                 break;
         case DS:
         case ES: