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, 36 insertions, 1 deletions

diff --git a/include/asm-powerpc/sigcontext.h b/include/asm-powerpc/sigcontext.h
index 165d630e1cf3..9c1f24fd5d11 100644
--- a/include/asm-powerpc/sigcontext.h
+++ b/include/asm-powerpc/sigcontext.h
@@ -43,9 +43,44 @@ struct sigcontext {
  * it must be copied via a vector register to/from storage) or as a word.
  * The entry with index 33 contains the vrsave as the first word (offset 0)
  * within the quadword.
+ *
+ * Part of the VSX data is stored here also by extending vmx_restore
+ * by an additional 32 double words.  Architecturally the layout of
+ * the VSR registers and how they overlap on top of the legacy FPR and
+ * VR registers is shown below:
+ *
+ *                    VSR doubleword 0               VSR doubleword 1
+ *           ----------------------------------------------------------------
+ *   VSR[0]  |             FPR[0]            |                              |
+ *           ----------------------------------------------------------------
+ *   VSR[1]  |             FPR[1]            |                              |
+ *           ----------------------------------------------------------------
+ *           |              ...              |                              |
+ *           |              ...              |                              |
+ *           ----------------------------------------------------------------
+ *   VSR[30] |             FPR[30]           |                              |
+ *           ----------------------------------------------------------------
+ *   VSR[31] |             FPR[31]           |                              |
+ *           ----------------------------------------------------------------
+ *   VSR[32] |                             VR[0]                            |
+ *           ----------------------------------------------------------------
+ *   VSR[33] |                             VR[1]                            |
+ *           ----------------------------------------------------------------
+ *           |                              ...                             |
+ *           |                              ...                             |
+ *           ----------------------------------------------------------------
+ *   VSR[62] |                             VR[30]                           |
+ *           ----------------------------------------------------------------
+ *   VSR[63] |                             VR[31]                           |
+ *           ----------------------------------------------------------------
+ *
+ * FPR/VSR 0-31 doubleword 0 is stored in fp_regs, and VMX/VSR 32-63
+ * is stored at the start of vmx_reserve.  vmx_reserve is extended for
+ * backwards compatility to store VSR 0-31 doubleword 1 after the VMX
+ * registers and vscr/vrsave.
  */
 	elf_vrreg_t	__user *v_regs;
-	long		vmx_reserve[ELF_NVRREG+ELF_NVRREG+1];
+	long		vmx_reserve[ELF_NVRREG+ELF_NVRREG+32+1];
 #endif
 };