[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>

1 files changed, 44 insertions, 1 deletions

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 7e8ded051b5b..4aae0c387645 100644
--- 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;