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[S390] kprobes: instruction fixup
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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>
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Martin Schwidefsky authored and Martin Schwidefsky committed Jan 5, 2011
1 parent 5a8b589 commit ba640a5
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Showing 2 changed files with 57 additions and 78 deletions.
5 changes: 0 additions & 5 deletions arch/s390/include/asm/kprobes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -59,9 +59,6 @@ typedef u16 kprobe_opcode_t;
struct arch_specific_insn {
/* copy of original instruction */
kprobe_opcode_t *insn;
int fixup;
int ilen;
int reg;
};

struct prev_kprobe {
Expand All @@ -83,8 +80,6 @@ struct kprobe_ctlblk {

void arch_remove_kprobe(struct kprobe *p);
void kretprobe_trampoline(void);
int is_prohibited_opcode(kprobe_opcode_t *instruction);
void get_instruction_type(struct arch_specific_insn *ainsn);

int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
int kprobe_exceptions_notify(struct notifier_block *self,
Expand Down
130 changes: 57 additions & 73 deletions arch/s390/kernel/kprobes.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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 */
Expand All @@ -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 {
Expand Down Expand Up @@ -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);
}
Expand Down

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