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[PATCH] Kprobes IA64: arch_prepare_kprobes() cleanup
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arch_prepare_kprobes() was doing lots of functionality
in just one single function. This patch
attempts to clean up arch_prepare_kprobes() by moving
specific sub task to the following (new)functions
1)valid_kprobe_addr() -->> validate the given kprobe address
2)get_kprobe_inst(slot..)->> Retrives the instruction for a given slot from the bundle
3)prepare_break_inst() -->> Prepares break instruction within the bundle
	3a)update_kprobe_inst_flag()-->>Updates the internal flags, required
			for proper emulation of the instruction at later
			point in time.

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Anil S Keshavamurthy authored and Linus Torvalds committed Jun 23, 2005
1 parent 13608d6 commit a540318
Showing 1 changed file with 121 additions and 70 deletions.
191 changes: 121 additions & 70 deletions arch/ia64/kernel/kprobes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -81,90 +81,141 @@ static enum instruction_type bundle_encoding[32][3] = {
{ u, u, u }, /* 1F */
};

int arch_prepare_kprobe(struct kprobe *p)
/*
* In this function we check to see if the instruction
* is IP relative instruction and update the kprobe
* inst flag accordingly
*/
static void update_kprobe_inst_flag(uint template, uint slot, uint major_opcode,
unsigned long kprobe_inst, struct kprobe *p)
{
unsigned long addr = (unsigned long) p->addr;
unsigned long *bundle_addr = (unsigned long *)(addr & ~0xFULL);
unsigned long slot = addr & 0xf;
unsigned long template;
unsigned long major_opcode = 0;
unsigned long lx_type_inst = 0;
unsigned long kprobe_inst = 0;
bundle_t *bundle = &p->ainsn.insn.bundle;

memcpy(&p->opcode.bundle, bundle_addr, sizeof(bundle_t));
memcpy(&p->ainsn.insn.bundle, bundle_addr, sizeof(bundle_t));

p->ainsn.inst_flag = 0;
p->ainsn.target_br_reg = 0;

template = bundle->quad0.template;
if (bundle_encoding[template][slot] == B) {
switch (major_opcode) {
case INDIRECT_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
case IP_RELATIVE_PREDICT_OPCODE:
case IP_RELATIVE_BRANCH_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
break;
case IP_RELATIVE_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
}
} else if (bundle_encoding[template][slot] == X) {
switch (major_opcode) {
case LONG_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
}
}
return;
}

if (((bundle_encoding[template][1] == L) && slot > 1) || (slot > 2)) {
printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",
addr);
return -EINVAL;
/*
* In this function we override the bundle with
* the break instruction at the given slot.
*/
static void prepare_break_inst(uint template, uint slot, uint major_opcode,
unsigned long kprobe_inst, struct kprobe *p)
{
unsigned long break_inst = BREAK_INST;
bundle_t *bundle = &p->ainsn.insn.bundle;

/*
* Copy the original kprobe_inst qualifying predicate(qp)
* to the break instruction
*/
break_inst |= (0x3f & kprobe_inst);

switch (slot) {
case 0:
bundle->quad0.slot0 = break_inst;
break;
case 1:
bundle->quad0.slot1_p0 = break_inst;
bundle->quad1.slot1_p1 = break_inst >> (64-46);
break;
case 2:
bundle->quad1.slot2 = break_inst;
break;
}

if (slot == 1 && bundle_encoding[template][1] == L) {
lx_type_inst = 1;
slot = 2;
}
/*
* Update the instruction flag, so that we can
* emulate the instruction properly after we
* single step on original instruction
*/
update_kprobe_inst_flag(template, slot, major_opcode, kprobe_inst, p);
}

static inline void get_kprobe_inst(bundle_t *bundle, uint slot,
unsigned long *kprobe_inst, uint *major_opcode)
{
unsigned long kprobe_inst_p0, kprobe_inst_p1;
unsigned int template;

template = bundle->quad0.template;

switch (slot) {
case 0:
major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
kprobe_inst = bundle->quad0.slot0;
bundle->quad0.slot0 = BREAK_INST | (0x3f & kprobe_inst);
case 0:
*major_opcode = (bundle->quad0.slot0 >> SLOT0_OPCODE_SHIFT);
*kprobe_inst = bundle->quad0.slot0;
break;
case 1:
major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
kprobe_inst = (bundle->quad0.slot1_p0 |
(bundle->quad1.slot1_p1 << (64-46)));
bundle->quad0.slot1_p0 = BREAK_INST | (0x3f & kprobe_inst);
bundle->quad1.slot1_p1 = (BREAK_INST >> (64-46));
case 1:
*major_opcode = (bundle->quad1.slot1_p1 >> SLOT1_p1_OPCODE_SHIFT);
kprobe_inst_p0 = bundle->quad0.slot1_p0;
kprobe_inst_p1 = bundle->quad1.slot1_p1;
*kprobe_inst = kprobe_inst_p0 | (kprobe_inst_p1 << (64-46));
break;
case 2:
major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
kprobe_inst = bundle->quad1.slot2;
bundle->quad1.slot2 = BREAK_INST | (0x3f & kprobe_inst);
case 2:
*major_opcode = (bundle->quad1.slot2 >> SLOT2_OPCODE_SHIFT);
*kprobe_inst = bundle->quad1.slot2;
break;
}
}

/*
* Look for IP relative Branches, IP relative call or
* IP relative predicate instructions
*/
if (bundle_encoding[template][slot] == B) {
switch (major_opcode) {
case INDIRECT_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
case IP_RELATIVE_PREDICT_OPCODE:
case IP_RELATIVE_BRANCH_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
break;
case IP_RELATIVE_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_RELATIVE_IP_ADDR;
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
default:
/* Do nothing */
break;
}
} else if (lx_type_inst) {
switch (major_opcode) {
case LONG_CALL_OPCODE:
p->ainsn.inst_flag |= INST_FLAG_FIX_BRANCH_REG;
p->ainsn.target_br_reg = ((kprobe_inst >> 6) & 0x7);
break;
default:
/* Do nothing */
break;
}
static int valid_kprobe_addr(int template, int slot, unsigned long addr)
{
if ((slot > 2) || ((bundle_encoding[template][1] == L) && slot > 1)) {
printk(KERN_WARNING "Attempting to insert unaligned kprobe at 0x%lx\n",
addr);
return -EINVAL;
}
return 0;
}

int arch_prepare_kprobe(struct kprobe *p)
{
unsigned long addr = (unsigned long) p->addr;
unsigned long *kprobe_addr = (unsigned long *)(addr & ~0xFULL);
unsigned long kprobe_inst=0;
unsigned int slot = addr & 0xf, template, major_opcode = 0;
bundle_t *bundle = &p->ainsn.insn.bundle;

memcpy(&p->opcode.bundle, kprobe_addr, sizeof(bundle_t));
memcpy(&p->ainsn.insn.bundle, kprobe_addr, sizeof(bundle_t));

template = bundle->quad0.template;

if(valid_kprobe_addr(template, slot, addr))
return -EINVAL;

/* Move to slot 2, if bundle is MLX type and kprobe slot is 1 */
if (slot == 1 && bundle_encoding[template][1] == L)
slot++;

/* Get kprobe_inst and major_opcode from the bundle */
get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);

prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);

return 0;
}
Expand Down Expand Up @@ -260,7 +311,7 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs)
if (regs->cr_iip == bundle_addr) {
regs->cr_iip = resume_addr;
}
}
}

turn_ss_off:
/* Turn off Single Step bit */
Expand Down

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