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, 30 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index a587b33cd6b9..34f37e59bacc 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -123,6 +123,22 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
                 buf[i] = current->thread.TS_FPR(i);
         memcpy(&buf[i], &current->thread.fpscr, sizeof(double));
         err |= __copy_to_user(&sc->fp_regs, buf, FP_REGS_SIZE);
+        /*
+         * Copy VSX low doubleword to local buffer for formatting,
+         * then out to userspace.  Update v_regs to point after the
+         * VMX data.
+         */
+        if (current->thread.used_vsr) {
+                flush_vsx_to_thread(current);
+                v_regs += ELF_NVRREG;
+                for (i = 0; i < 32 ; i++)
+                        buf[i] = current->thread.fpr[i][TS_VSRLOWOFFSET];
+                err |= __copy_to_user(v_regs, buf, 32 * sizeof(double));
+                /* set MSR_VSX in the MSR value in the frame to
+                 * indicate that sc->vs_reg) contains valid data.
+                 */
+                msr |= MSR_VSX;
+        }
 #else /* CONFIG_VSX */
         /* copy fpr regs and fpscr */
         err |= __copy_to_user(&sc->fp_regs, &current->thread.fpr, FP_REGS_SIZE);
@@ -197,7 +213,7 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
          * This has to be done before copying stuff into current->thread.fpr/vr
          * for the reasons explained in the previous comment.
          */
-        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC);
+        regs->msr &= ~(MSR_FP | MSR_FE0 | MSR_FE1 | MSR_VEC | MSR_VSX);
 
 #ifdef CONFIG_ALTIVEC
         err |= __get_user(v_regs, &sc->v_regs);
@@ -226,6 +242,19 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
                 current->thread.TS_FPR(i) = buf[i];
         memcpy(&current->thread.fpscr, &buf[i], sizeof(double));
 
+        /*
+         * Get additional VSX data. Update v_regs to point after the
+         * VMX data.  Copy VSX low doubleword from userspace to local
+         * buffer for formatting, then into the taskstruct.
+         */
+        v_regs += ELF_NVRREG;
+        if ((msr & MSR_VSX) != 0)
+                err |= __copy_from_user(buf, v_regs, 32 * sizeof(double));
+        else
+                memset(buf, 0, 32 * sizeof(double));
+
+        for (i = 0; i < 32 ; i++)
+                current->thread.fpr[i][TS_VSRLOWOFFSET] = buf[i];
 #else
         err |= __copy_from_user(&current->thread.fpr, &sc->fp_regs, FP_REGS_SIZE);
 #endif