[PATCH 2/5] powerpc/lib/sstep: Add popcnt instruction emulation

[Matt Brown]

This adds emulations for the popcntb, popcntw, and popcntd instructions.

Signed-off-by: Matt Brown <matthew.brown....@gmail.com>
---
 arch/powerpc/lib/sstep.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index f3e9ba8..cf69987 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -613,6 +613,30 @@ static nokprobe_inline void do_cmpb(struct pt_regs *regs, 
unsigned long v1,
        regs->gpr[rd] = out_val;
 }
 
+/*
+ * The size parameter is used to ajust the equivalent popcnt instruction.
+ * popcntb = 8, popcntw = 32, popcntd = 64
+ */
+static nokprobe_inline void do_popcnt(struct pt_regs *regs, unsigned long v1,
+                               int size, int ra)
+{
+       unsigned int out_val, mask, n;
+       int i, j;
+
+       out_val = 0;
+
+       for (i = 0; i < (64 / size); i++) {
+               n = 0;
+               for (j = 0; j < size; j++) {
+                       mask = 1 << (j + (i * size));
+                       if (v1 & mask)
+                               n++;
+               }
+               out_val |= n << (i * size);
+       }
+       regs->gpr[ra] = out_val;
+}
+
 static nokprobe_inline int trap_compare(long v1, long v2)
 {
        int ret = 0;
@@ -1234,6 +1258,21 @@ int analyse_instr(struct instruction_op *op, struct 
pt_regs *regs,
                        regs->gpr[ra] = (signed int) regs->gpr[rd];
                        goto logical_done;
 #endif
+               case 299528:    /* popcntb */
+                       val = regs->gpr[rd];
+                       do_popcnt(regs, val, 8, ra);
+                       goto logical_done;
+
+               case 17076744:  /* popcntw */
+                       val = regs->gpr[rd];
+                       do_popcnt(regs, val, 32, ra);
+                       goto logical_done;
+#ifdef __powerpc64__
+               case 19173896:  /* popcntd */
+                       val = regs->gpr[rd];
+                       do_popcnt(regs, val, 64, ra);
+                       goto logical_done;
+#endif
 
 /*
  * Shift instructions
-- 
2.9.3