x86: x86-64 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, 34 insertions, 2 deletions

diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c
index 2427548f2a01..5979dbe8e0a2 100644
--- a/arch/x86/kernel/ptrace_64.c
+++ b/arch/x86/kernel/ptrace_64.c
@@ -67,21 +67,29 @@ static int putreg(struct task_struct *child,
                 if (value && (value & 3) != 3)
                         return -EIO;
                 child->thread.fsindex = value & 0xffff;
+                if (child == current)
+                        loadsegment(fs, child->thread.fsindex);
                 return 0;
         case offsetof(struct user_regs_struct,gs):
                 if (value && (value & 3) != 3)
                         return -EIO;
                 child->thread.gsindex = value & 0xffff;
+                if (child == current)
+                        load_gs_index(child->thread.gsindex);
                 return 0;
         case offsetof(struct user_regs_struct,ds):
                 if (value && (value & 3) != 3)
                         return -EIO;
                 child->thread.ds = value & 0xffff;
+                if (child == current)
+                        loadsegment(ds, child->thread.ds);
                 return 0;
         case offsetof(struct user_regs_struct,es):
                 if (value && (value & 3) != 3)
                         return -EIO;
                 child->thread.es = value & 0xffff;
+                if (child == current)
+                        loadsegment(es, child->thread.es);
                 return 0;
         case offsetof(struct user_regs_struct,ss):
                 if ((value & 3) != 3)
@@ -135,14 +143,32 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
 {
         struct pt_regs *regs = task_pt_regs(child);
         unsigned long val;
+        unsigned int seg;
         switch (regno) {
         case offsetof(struct user_regs_struct, fs):
+                if (child == current) {
+                        /* Older gas can't assemble movq %?s,%r?? */
+                        asm("movl %%fs,%0" : "=r" (seg));
+                        return seg;
+                }
                 return child->thread.fsindex;
         case offsetof(struct user_regs_struct, gs):
+                if (child == current) {
+                        asm("movl %%gs,%0" : "=r" (seg));
+                        return seg;
+                }
                 return child->thread.gsindex;
         case offsetof(struct user_regs_struct, ds):
+                if (child == current) {
+                        asm("movl %%ds,%0" : "=r" (seg));
+                        return seg;
+                }
                 return child->thread.ds;
         case offsetof(struct user_regs_struct, es):
+                if (child == current) {
+                        asm("movl %%es,%0" : "=r" (seg));
+                        return seg;
+                }
                 return child->thread.es;
         case offsetof(struct user_regs_struct, fs_base):
                 /*
@@ -152,7 +178,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
                  */
                 if (child->thread.fs != 0)
                         return child->thread.fs;
-                if (child->thread.fsindex != FS_TLS_SEL)
+                seg = child->thread.fsindex;
+                if (child == current)
+                        asm("movl %%fs,%0" : "=r" (seg));
+                if (seg != FS_TLS_SEL)
                         return 0;
                 return get_desc_base(&child->thread.tls_array[FS_TLS]);
         case offsetof(struct user_regs_struct, gs_base):
@@ -161,7 +190,10 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno)
                  */
                 if (child->thread.gs != 0)
                         return child->thread.gs;
-                if (child->thread.gsindex != GS_TLS_SEL)
+                seg = child->thread.gsindex;
+                if (child == current)
+                        asm("movl %%gs,%0" : "=r" (seg));
+                if (seg != GS_TLS_SEL)
                         return 0;
                 return get_desc_base(&child->thread.tls_array[GS_TLS]);
         case offsetof(struct user_regs_struct, flags):