[S390] kprobes: instruction fixup

Determine instruction fixup details in resume_execution, no need to do
it beforehand. Remove fixup, ilen and reg from arch_specific_insn.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 57 insertions, 73 deletions

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 1e75ec523577..fcbc25836879 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -37,29 +37,9 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
 
-int __kprobes arch_prepare_kprobe(struct kprobe *p)
+static int __kprobes is_prohibited_opcode(kprobe_opcode_t *insn)
 {
-        /* Make sure the probe isn't going on a difficult instruction */
-        if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
-                return -EINVAL;
-
-        if ((unsigned long)p->addr & 0x01)
-                return -EINVAL;
-
-        /* Use the get_insn_slot() facility for correctness */
-        if (!(p->ainsn.insn = get_insn_slot()))
-                return -ENOMEM;
-
-        memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
-
-        get_instruction_type(&p->ainsn);
-        p->opcode = *p->addr;
-        return 0;
-}
-
-int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
-{
-        switch (*(__u8 *) instruction) {
+        switch (insn[0] >> 8) {
         case 0x0c:      /* bassm */
         case 0x0b:      /* bsm   */
         case 0x83:      /* diag  */
@@ -68,7 +48,7 @@ int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
         case 0xad:      /* stosm */
                 return -EINVAL;
         }
-        switch (*(__u16 *) instruction) {
+        switch (insn[0]) {
         case 0x0101:    /* pr    */
         case 0xb25a:    /* bsa   */
         case 0xb240:    /* bakr  */
@@ -81,80 +61,79 @@ int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
         return 0;
 }
 
-void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
+static int __kprobes get_fixup_type(kprobe_opcode_t *insn)
 {
         /* default fixup method */
-        ainsn->fixup = FIXUP_PSW_NORMAL;
-
-        /* save r1 operand */
-        ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
-
-        /* save the instruction length (pop 5-5) in bytes */
-        switch (*(__u8 *) (ainsn->insn) >> 6) {
-        case 0:
-                ainsn->ilen = 2;
-                break;
-        case 1:
-        case 2:
-                ainsn->ilen = 4;
-                break;
-        case 3:
-                ainsn->ilen = 6;
-                break;
-        }
+        int fixup = FIXUP_PSW_NORMAL;
 
-        switch (*(__u8 *) ainsn->insn) {
+        switch (insn[0] >> 8) {
         case 0x05:      /* balr */
         case 0x0d:      /* basr */
-                ainsn->fixup = FIXUP_RETURN_REGISTER;
+                fixup = FIXUP_RETURN_REGISTER;
                 /* if r2 = 0, no branch will be taken */
-                if ((*ainsn->insn & 0x0f) == 0)
-                        ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
+                if ((insn[0] & 0x0f) == 0)
+                        fixup |= FIXUP_BRANCH_NOT_TAKEN;
                 break;
         case 0x06:      /* bctr */
         case 0x07:      /* bcr  */
-                ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+                fixup = FIXUP_BRANCH_NOT_TAKEN;
                 break;
         case 0x45:      /* bal  */
         case 0x4d:      /* bas  */
-                ainsn->fixup = FIXUP_RETURN_REGISTER;
+                fixup = FIXUP_RETURN_REGISTER;
                 break;
         case 0x47:      /* bc   */
         case 0x46:      /* bct  */
         case 0x86:      /* bxh  */
         case 0x87:      /* bxle */
-                ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+                fixup = FIXUP_BRANCH_NOT_TAKEN;
                 break;
         case 0x82:      /* lpsw */
-                ainsn->fixup = FIXUP_NOT_REQUIRED;
+                fixup = FIXUP_NOT_REQUIRED;
                 break;
         case 0xb2:      /* lpswe */
-                if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
-                        ainsn->fixup = FIXUP_NOT_REQUIRED;
-                }
+                if ((insn[0] & 0xff) == 0xb2)
+                        fixup = FIXUP_NOT_REQUIRED;
                 break;
         case 0xa7:      /* bras */
-                if ((*ainsn->insn & 0x0f) == 0x05) {
-                        ainsn->fixup |= FIXUP_RETURN_REGISTER;
-                }
+                if ((insn[0] & 0x0f) == 0x05)
+                        fixup |= FIXUP_RETURN_REGISTER;
                 break;
         case 0xc0:
-                if ((*ainsn->insn & 0x0f) == 0x00  /* larl  */
-                        || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
-                ainsn->fixup |= FIXUP_RETURN_REGISTER;
+                if ((insn[0] & 0x0f) == 0x00 || /* larl  */
+                    (insn[0] & 0x0f) == 0x05)   /* brasl */
+                fixup |= FIXUP_RETURN_REGISTER;
                 break;
         case 0xeb:
-                if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 ||   /* bxhg  */
-                        *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
-                        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
-                }
+                if ((insn[2] & 0xff) == 0x44 || /* bxhg  */
+                    (insn[2] & 0xff) == 0x45)   /* bxleg */
+                        fixup = FIXUP_BRANCH_NOT_TAKEN;
                 break;
         case 0xe3:      /* bctg */
-                if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
-                        ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
-                }
+                if ((insn[2] & 0xff) == 0x46)
+                        fixup = FIXUP_BRANCH_NOT_TAKEN;
                 break;
         }
+        return fixup;
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+        if ((unsigned long) p->addr & 0x01)
+                return -EINVAL;
+
+        /* Make sure the probe isn't going on a difficult instruction */
+        if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
+                return -EINVAL;
+
+        /* Use the get_insn_slot() facility for correctness */
+        if (!(p->ainsn.insn = get_insn_slot()))
+                return -ENOMEM;
+
+        p->opcode = *p->addr;
+        memcpy(p->ainsn.insn, p->addr, ((p->opcode >> 14) + 3) & -2);
+
+        return 0;
 }
 
 struct ins_replace_args {
@@ -444,17 +423,22 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
 {
         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
         unsigned long ip = regs->psw.addr & PSW_ADDR_INSN;
+        int fixup = get_fixup_type(p->ainsn.insn);
 
-        if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
+        if (fixup & FIXUP_PSW_NORMAL)
                 ip += (unsigned long) p->addr - (unsigned long) p->ainsn.insn;
 
-        if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
-                if (ip - (unsigned long) p->ainsn.insn == p->ainsn.ilen)
-                        ip = (unsigned long) p->addr + p->ainsn.ilen;
+        if (fixup & FIXUP_BRANCH_NOT_TAKEN) {
+                int ilen = ((p->ainsn.insn[0] >> 14) + 3) & -2;
+                if (ip - (unsigned long) p->ainsn.insn == ilen)
+                        ip = (unsigned long) p->addr + ilen;
+        }
 
-        if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
-                regs->gprs[p->ainsn.reg] += (unsigned long) p->addr -
-                                            (unsigned long) p->ainsn.insn;
+        if (fixup & FIXUP_RETURN_REGISTER) {
+                int reg = (p->ainsn.insn[0] & 0xf0) >> 4;
+                regs->gprs[reg] += (unsigned long) p->addr -
+                                   (unsigned long) p->ainsn.insn;
+        }
 
         disable_singlestep(kcb, regs, ip);
 }