[POWERPC] Emulate more instructions in software

Emulate a few more instructions in software - especially useful during
singlestepping (xmon/kprobes).

Instructions emulated with this patch are mfcr/mtcr rX, mfxer/mtxer rX,
mflr/mtlr rX, mfctr/mtctr rX and mr rA,rB.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 7e8ded0..4aae0c3 100644 (file)
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -54,7 +54,7 @@ static int __kprobes branch_taken(unsigned int instr, struct pt_regs *regs)
  */
 int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 {
-       unsigned int opcode, rd;
+       unsigned int opcode, rs, rb, rd, spr;
        unsigned long int imm;
 
        opcode = instr >> 26;
@@ -152,6 +152,49 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
                                regs->nip &= 0xffffffffUL;
                        return 1;
 #endif
+               case 0x26:      /* mfcr */
+                       regs->gpr[rd] = regs->ccr;
+                       regs->gpr[rd] &= 0xffffffffUL;
+                       goto mtspr_out;
+               case 0x2a6:     /* mfspr */
+                       spr = (instr >> 11) & 0x3ff;
+                       switch (spr) {
+                       case 0x20:      /* mfxer */
+                               regs->gpr[rd] = regs->xer;
+                               regs->gpr[rd] &= 0xffffffffUL;
+                               goto mtspr_out;
+                       case 0x100:     /* mflr */
+                               regs->gpr[rd] = regs->link;
+                               goto mtspr_out;
+                       case 0x120:     /* mfctr */
+                               regs->gpr[rd] = regs->ctr;
+                               goto mtspr_out;
+                       }
+                       break;
+               case 0x378:     /* orx */
+                       rs = (instr >> 21) & 0x1f;
+                       rb = (instr >> 11) & 0x1f;
+                       if (rs == rb) {         /* mr */
+                               rd = (instr >> 16) & 0x1f;
+                               regs->gpr[rd] = regs->gpr[rs];
+                               goto mtspr_out;
+                       }
+                       break;
+               case 0x3a6:     /* mtspr */
+                       spr = (instr >> 11) & 0x3ff;
+                       switch (spr) {
+                       case 0x20:      /* mtxer */
+                               regs->xer = (regs->gpr[rd] & 0xffffffffUL);
+                               goto mtspr_out;
+                       case 0x100:     /* mtlr */
+                               regs->link = regs->gpr[rd];
+                               goto mtspr_out;
+                       case 0x120:     /* mtctr */
+                               regs->ctr = regs->gpr[rd];
+mtspr_out:
+                               regs->nip += 4;
+                               return 1;
+                       }
                }
        }
        return 0;