powerpc: sstep: Add support for darn instruction

This adds emulation support for the following integer instructions:
  * Deliver A Random Number (darn)

As suggested by Michael, this uses a raw .long for specifying the
instruction word when using inline assembly to retain compatibility
with older binutils.

Signed-off-by: Sandipan Das <sandipan@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 67e69eb..ab575e0 100644 (file)
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1728,6 +1728,28 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
                                (int) regs->gpr[rb];
                        goto arith_done;
 
+               case 755:       /* darn */
+                       if (!cpu_has_feature(CPU_FTR_ARCH_300))
+                               return -1;
+                       switch (ra & 0x3) {
+                       case 0:
+                               /* 32-bit conditioned */
+                               asm volatile(PPC_DARN(%0, 0) : "=r" (op->val));
+                               goto compute_done;
+
+                       case 1:
+                               /* 64-bit conditioned */
+                               asm volatile(PPC_DARN(%0, 1) : "=r" (op->val));
+                               goto compute_done;
+
+                       case 2:
+                               /* 64-bit raw */
+                               asm volatile(PPC_DARN(%0, 2) : "=r" (op->val));
+                               goto compute_done;
+                       }
+
+                       return -1;
+
 
 /*
  * Logical instructions