8 files changed, 106 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/emulated_ops.h b/arch/powerpc/include/asm/emulated_ops.h
index f0fb4fc1f6e6..45921672b97a 100644
--- a/arch/powerpc/include/asm/emulated_ops.h
+++ b/arch/powerpc/include/asm/emulated_ops.h
@@ -52,6 +52,10 @@ extern struct ppc_emulated {
 #ifdef CONFIG_VSX
         struct ppc_emulated_entry vsx;
 #endif
+#ifdef CONFIG_PPC64
+        struct ppc_emulated_entry mfdscr;
+        struct ppc_emulated_entry mtdscr;
+#endif
 } ppc_emulated;
 
 extern u32 ppc_warn_emulated;
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index 3e25b258568e..e472659d906c 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -41,6 +41,10 @@
 #define PPC_INST_RFCI                   0x4c000066
 #define PPC_INST_RFDI                   0x4c00004e
 #define PPC_INST_RFMCI                  0x4c00004c
+#define PPC_INST_MFSPR_DSCR             0x7c1102a6
+#define PPC_INST_MFSPR_DSCR_MASK        0xfc1fffff
+#define PPC_INST_MTSPR_DSCR             0x7c1103a6
+#define PPC_INST_MTSPR_DSCR_MASK        0xfc1fffff
 
 #define PPC_INST_STRING                 0x7c00042a
 #define PPC_INST_STRING_MASK            0xfc0007fe
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index de1967a1ff57..d50c2b6d9bc3 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -238,6 +238,10 @@ struct thread_struct {
 #ifdef CONFIG_KVM_BOOK3S_32_HANDLER
         void*           kvm_shadow_vcpu; /* KVM internal data */
 #endif /* CONFIG_KVM_BOOK3S_32_HANDLER */
+#ifdef CONFIG_PPC64
+        unsigned long   dscr;
+        int             dscr_inherit;
+#endif
 };
 
 #define ARCH_MIN_TASKALIGN 16
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 23e6a93145ab..6887661ac072 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -74,6 +74,7 @@ int main(void)
         DEFINE(AUDITCONTEXT, offsetof(struct task_struct, audit_context));
         DEFINE(SIGSEGV, SIGSEGV);
         DEFINE(NMI_MASK, NMI_MASK);
+        DEFINE(THREAD_DSCR, offsetof(struct thread_struct, dscr));
 #else
         DEFINE(THREAD_INFO, offsetof(struct task_struct, stack));
 #endif /* CONFIG_PPC64 */
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index dbf5bfafd7bc..64693706ebfd 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -421,6 +421,12 @@ BEGIN_FTR_SECTION
         std     r24,THREAD_VRSAVE(r3)
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_PPC64
+BEGIN_FTR_SECTION
+        mfspr   r25,SPRN_DSCR
+        std     r25,THREAD_DSCR(r3)
+END_FTR_SECTION_IFSET(CPU_FTR_DSCR)
+#endif
         and.    r0,r0,r22
         beq+    1f
         andc    r22,r22,r0
@@ -522,6 +528,15 @@ BEGIN_FTR_SECTION
         mtspr   SPRN_VRSAVE,r0          /* if G4, restore VRSAVE reg */
 END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_PPC64
+BEGIN_FTR_SECTION
+        ld      r0,THREAD_DSCR(r4)
+        cmpd    r0,r25
+        beq     1f
+        mtspr   SPRN_DSCR,r0
+1:      
+END_FTR_SECTION_IFSET(CPU_FTR_DSCR)
+#endif
 
         /* r3-r13 are destroyed -- Cort */
         REST_8GPRS(14, r1)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f74f355a9617..a01c2d93fd2f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -702,6 +702,8 @@ void prepare_to_copy(struct task_struct *tsk)
 /*
  * Copy a thread..
  */
+extern unsigned long dscr_default; /* defined in arch/powerpc/kernel/sysfs.c */
+
 int copy_thread(unsigned long clone_flags, unsigned long usp,
                 unsigned long unused, struct task_struct *p,
                 struct pt_regs *regs)
@@ -769,6 +771,20 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
                 p->thread.ksp_vsid = sp_vsid;
         }
 #endif /* CONFIG_PPC_STD_MMU_64 */
+#ifdef CONFIG_PPC64 
+        if (cpu_has_feature(CPU_FTR_DSCR)) {
+                if (current->thread.dscr_inherit) {
+                        p->thread.dscr_inherit = 1;
+                        p->thread.dscr = current->thread.dscr;
+                } else if (0 != dscr_default) {
+                        p->thread.dscr_inherit = 1;
+                        p->thread.dscr = dscr_default;
+                } else {
+                        p->thread.dscr_inherit = 0;
+                        p->thread.dscr = 0;
+                }
+        }
+#endif
 
         /*
          * The PPC64 ABI makes use of a TOC to contain function 
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index c0d8c2006bf4..f0f2199e64e1 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -182,6 +182,41 @@ static SYSDEV_ATTR(mmcra, 0600, show_mmcra, store_mmcra);
 static SYSDEV_ATTR(spurr, 0600, show_spurr, NULL);
 static SYSDEV_ATTR(dscr, 0600, show_dscr, store_dscr);
 static SYSDEV_ATTR(purr, 0600, show_purr, store_purr);
+
+unsigned long dscr_default = 0;
+EXPORT_SYMBOL(dscr_default);
+
+static ssize_t show_dscr_default(struct sysdev_class *class,
+                struct sysdev_class_attribute *attr, char *buf)
+{
+        return sprintf(buf, "%lx\n", dscr_default);
+}
+
+static ssize_t __used store_dscr_default(struct sysdev_class *class,
+                struct sysdev_class_attribute *attr, const char *buf,
+                size_t count)
+{
+        unsigned long val;
+        int ret = 0;
+        
+        ret = sscanf(buf, "%lx", &val);
+        if (ret != 1)
+                return -EINVAL;
+        dscr_default = val;
+
+        return count;
+}
+
+static SYSDEV_CLASS_ATTR(dscr_default, 0600,
+                show_dscr_default, store_dscr_default);
+
+static void sysfs_create_dscr_default(void)
+{
+        int err = 0;
+        if (cpu_has_feature(CPU_FTR_DSCR))
+                err = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
+                        &attr_dscr_default.attr);
+}
 #endif /* CONFIG_PPC64 */
 
 #ifdef HAS_PPC_PMC_PA6T
@@ -617,6 +652,9 @@ static int __init topology_init(void)
                 if (cpu_online(cpu))
                         register_cpu_online(cpu);
         }
+#ifdef CONFIG_PPC64
+        sysfs_create_dscr_default();
+#endif /* CONFIG_PPC64 */
 
         return 0;
 }
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 5ddb801bc154..cb71cf29edea 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -909,6 +909,26 @@ static int emulate_instruction(struct pt_regs *regs)
                 return emulate_isel(regs, instword);
         }
 
+#ifdef CONFIG_PPC64
+        /* Emulate the mfspr rD, DSCR. */
+        if (((instword & PPC_INST_MFSPR_DSCR_MASK) == PPC_INST_MFSPR_DSCR) &&
+                        cpu_has_feature(CPU_FTR_DSCR)) {
+                PPC_WARN_EMULATED(mfdscr, regs);
+                rd = (instword >> 21) & 0x1f;
+                regs->gpr[rd] = mfspr(SPRN_DSCR);
+                return 0;
+        }
+        /* Emulate the mtspr DSCR, rD. */
+        if (((instword & PPC_INST_MTSPR_DSCR_MASK) == PPC_INST_MTSPR_DSCR) &&
+                        cpu_has_feature(CPU_FTR_DSCR)) {
+                PPC_WARN_EMULATED(mtdscr, regs);
+                rd = (instword >> 21) & 0x1f;
+                mtspr(SPRN_DSCR, regs->gpr[rd]);
+                current->thread.dscr_inherit = 1;
+                return 0;
+        }
+#endif
+
         return -EINVAL;
 }
 
@@ -1506,6 +1526,10 @@ struct ppc_emulated ppc_emulated = {
 #ifdef CONFIG_VSX
         WARN_EMULATED_SETUP(vsx),
 #endif
+#ifdef CONFIG_PPC64
+        WARN_EMULATED_SETUP(mfdscr),
+        WARN_EMULATED_SETUP(mtdscr),
+#endif
 };
 
 u32 ppc_warn_emulated;