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>

diff --git a/arch/x86/kernel/ptrace_64.c b/arch/x86/kernel/ptrace_64.c
index 2427548..5979dbe 100644 (file)
--- 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):