powerpc: Add VSX context save/restore, ptrace and signal support

This patch extends the floating point save and restore code to use the
VSX load/stores when VSX is available.  This will make FP context
save/restore marginally slower on FP only code, when VSX is available,
as it has to load/store 128bits rather than just 64bits.

Mixing FP, VMX and VSX code will get constant architected state.

The signals interface is extended to enable access to VSR 0-31
doubleword 1 after discussions with tool chain maintainers.  Backward
compatibility is maintained.

The ptrace interface is also extended to allow access to VSR 0-31 full
registers.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 106 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 582df70439cb..d52ded366f14 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -53,6 +53,7 @@ extern unsigned long _get_SP(void);
 #ifndef CONFIG_SMP
 struct task_struct *last_task_used_math = NULL;
 struct task_struct *last_task_used_altivec = NULL;
+struct task_struct *last_task_used_vsx = NULL;
 struct task_struct *last_task_used_spe = NULL;
 #endif
 
@@ -106,11 +107,23 @@ EXPORT_SYMBOL(enable_kernel_fp);
 
 int dump_task_fpu(struct task_struct *tsk, elf_fpregset_t *fpregs)
 {
+#ifdef CONFIG_VSX
+        int i;
+        elf_fpreg_t *reg;
+#endif
+
         if (!tsk->thread.regs)
                 return 0;
         flush_fp_to_thread(current);
 
+#ifdef CONFIG_VSX
+        reg = (elf_fpreg_t *)fpregs;
+        for (i = 0; i < ELF_NFPREG - 1; i++, reg++)
+                *reg = tsk->thread.TS_FPR(i);
+        memcpy(reg, &tsk->thread.fpscr, sizeof(elf_fpreg_t));
+#else
         memcpy(fpregs, &tsk->thread.TS_FPR(0), sizeof(*fpregs));
+#endif
 
         return 1;
 }
@@ -149,7 +162,7 @@ void flush_altivec_to_thread(struct task_struct *tsk)
         }
 }
 
-int dump_task_altivec(struct task_struct *tsk, elf_vrregset_t *vrregs)
+int dump_task_altivec(struct task_struct *tsk, elf_vrreg_t *vrregs)
 {
         /* ELF_NVRREG includes the VSCR and VRSAVE which we need to save
          * separately, see below */
@@ -179,6 +192,80 @@ int dump_task_altivec(struct task_struct *tsk, elf_vrregset_t *vrregs)
 }
 #endif /* CONFIG_ALTIVEC */
 
+#ifdef CONFIG_VSX
+#if 0
+/* not currently used, but some crazy RAID module might want to later */
+void enable_kernel_vsx(void)
+{
+        WARN_ON(preemptible());
+
+#ifdef CONFIG_SMP
+        if (current->thread.regs && (current->thread.regs->msr & MSR_VSX))
+                giveup_vsx(current);
+        else
+                giveup_vsx(NULL);       /* just enable vsx for kernel - force */
+#else
+        giveup_vsx(last_task_used_vsx);
+#endif /* CONFIG_SMP */
+}
+EXPORT_SYMBOL(enable_kernel_vsx);
+#endif
+
+void flush_vsx_to_thread(struct task_struct *tsk)
+{
+        if (tsk->thread.regs) {
+                preempt_disable();
+                if (tsk->thread.regs->msr & MSR_VSX) {
+#ifdef CONFIG_SMP
+                        BUG_ON(tsk != current);
+#endif
+                        giveup_vsx(tsk);
+                }
+                preempt_enable();
+        }
+}
+
+/*
+ * This dumps the lower half 64bits of the first 32 VSX registers.
+ * This needs to be called with dump_task_fp and dump_task_altivec to
+ * get all the VSX state.
+ */
+int dump_task_vsx(struct task_struct *tsk, elf_vrreg_t *vrregs)
+{
+        elf_vrreg_t *reg;
+        double buf[32];
+        int i;
+
+        if (tsk == current)
+                flush_vsx_to_thread(tsk);
+
+        reg = (elf_vrreg_t *)vrregs;
+
+        for (i = 0; i < 32 ; i++)
+                buf[i] = current->thread.fpr[i][TS_VSRLOWOFFSET];
+        memcpy(reg, buf, sizeof(buf));
+
+        return 1;
+}
+#endif /* CONFIG_VSX */
+
+int dump_task_vector(struct task_struct *tsk, elf_vrregset_t *vrregs)
+{
+        int rc = 0;
+        elf_vrreg_t *regs = (elf_vrreg_t *)vrregs;
+#ifdef CONFIG_ALTIVEC
+        rc = dump_task_altivec(tsk, regs);
+        if (rc)
+                return rc;
+        regs += ELF_NVRREG;
+#endif
+
+#ifdef CONFIG_VSX
+        rc = dump_task_vsx(tsk, regs);
+#endif
+        return rc;
+}
+
 #ifdef CONFIG_SPE
 
 void enable_kernel_spe(void)
@@ -233,6 +320,10 @@ void discard_lazy_cpu_state(void)
         if (last_task_used_altivec == current)
                 last_task_used_altivec = NULL;
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+        if (last_task_used_vsx == current)
+                last_task_used_vsx = NULL;
+#endif /* CONFIG_VSX */
 #ifdef CONFIG_SPE
         if (last_task_used_spe == current)
                 last_task_used_spe = NULL;
@@ -297,6 +388,10 @@ struct task_struct *__switch_to(struct task_struct *prev,
         if (prev->thread.regs && (prev->thread.regs->msr & MSR_VEC))
                 giveup_altivec(prev);
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+        if (prev->thread.regs && (prev->thread.regs->msr & MSR_VSX))
+                giveup_vsx(prev);
+#endif /* CONFIG_VSX */
 #ifdef CONFIG_SPE
         /*
          * If the previous thread used spe in the last quantum
@@ -317,6 +412,10 @@ struct task_struct *__switch_to(struct task_struct *prev,
         if (new->thread.regs && last_task_used_altivec == new)
                 new->thread.regs->msr |= MSR_VEC;
 #endif /* CONFIG_ALTIVEC */
+#ifdef CONFIG_VSX
+        if (new->thread.regs && last_task_used_vsx == new)
+                new->thread.regs->msr |= MSR_VSX;
+#endif /* CONFIG_VSX */
 #ifdef CONFIG_SPE
         /* Avoid the trap.  On smp this this never happens since
          * we don't set last_task_used_spe
@@ -417,6 +516,8 @@ static struct regbit {
         {MSR_EE,        "EE"},
         {MSR_PR,        "PR"},
         {MSR_FP,        "FP"},
+        {MSR_VEC,       "VEC"},
+        {MSR_VSX,       "VSX"},
         {MSR_ME,        "ME"},
         {MSR_IR,        "IR"},
         {MSR_DR,        "DR"},
@@ -534,6 +635,7 @@ void prepare_to_copy(struct task_struct *tsk)
 {
         flush_fp_to_thread(current);
         flush_altivec_to_thread(current);
+        flush_vsx_to_thread(current);
         flush_spe_to_thread(current);
 }
 
@@ -689,6 +791,9 @@ void start_thread(struct pt_regs *regs, unsigned long start, unsigned long sp)
 #endif
 
         discard_lazy_cpu_state();
+#ifdef CONFIG_VSX
+        current->thread.used_vsr = 0;
+#endif
         memset(current->thread.fpr, 0, sizeof(current->thread.fpr));
         current->thread.fpscr.val = 0;
 #ifdef CONFIG_ALTIVEC