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[PATCH] Kprobes/IA64: support kprobe on branch/call instructions
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This patch is required to support kprobe on branch/call instructions.

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 b2761dc commit cd2675b
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Showing 2 changed files with 132 additions and 16 deletions.
131 changes: 116 additions & 15 deletions arch/ia64/kernel/kprobes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -120,25 +120,75 @@ void arch_arm_kprobe(struct kprobe *p)
unsigned long arm_addr = 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.inst_flag = 0;
p->ainsn.target_br_reg = 0;

memcpy(&bundle, &p->ainsn.insn.bundle, sizeof(bundle_t));
template = bundle.quad0.template;
if (slot == 1 && bundle_encoding[template][1] == L) {
lx_type_inst = 1;
slot = 2;
}


template = bundle.quad0.template;
if (slot == 1 && bundle_encoding[template][1] == L)
slot = 2;
switch (slot) {
case 0:
major_opcode = (bundle.quad0.slot0 >> SLOT0_OPCODE_SHIFT);
kprobe_inst = bundle.quad0.slot0;
bundle.quad0.slot0 = BREAK_INST;
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;
bundle.quad1.slot1_p1 = (BREAK_INST >> (64-46));
break;
case 2:
major_opcode = (bundle.quad1.slot2 >> SLOT2_OPCODE_SHIFT);
kprobe_inst = bundle.quad1.slot2;
bundle.quad1.slot2 = BREAK_INST;
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;
}
}

/* Flush icache for the instruction at the emulated address */
flush_icache_range((unsigned long)&p->ainsn.insn.bundle,
Expand Down Expand Up @@ -170,24 +220,75 @@ void arch_remove_kprobe(struct kprobe *p)
* We are resuming execution after a single step fault, so the pt_regs
* structure reflects the register state after we executed the instruction
* located in the kprobe (p->ainsn.insn.bundle). We still need to adjust
* the ip to point back to the original stack address, and if we see that
* the slot has incremented back to zero, then we need to point to the next
* slot location.
* the ip to point back to the original stack address. To set the IP address
* to original stack address, handle the case where we need to fixup the
* relative IP address and/or fixup branch register.
*/
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
{
unsigned long bundle = (unsigned long)p->addr & ~0xFULL;
unsigned long bundle_addr = ((unsigned long) (&p->ainsn.insn.bundle)) & ~0xFULL;
unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
unsigned long template;
int slot = ((unsigned long)p->addr & 0xf);

/*
* TODO: Handle cases where kprobe was inserted on a branch instruction
*/
template = p->opcode.bundle.quad0.template;

if (slot == 1 && bundle_encoding[template][1] == L)
slot = 2;

if (p->ainsn.inst_flag) {

if (!ia64_psr(regs)->ri)
regs->cr_iip = bundle + 0x10;
else
regs->cr_iip = bundle;
if (p->ainsn.inst_flag & INST_FLAG_FIX_RELATIVE_IP_ADDR) {
/* Fix relative IP address */
regs->cr_iip = (regs->cr_iip - bundle_addr) + resume_addr;
}

if (p->ainsn.inst_flag & INST_FLAG_FIX_BRANCH_REG) {
/*
* Fix target branch register, software convention is
* to use either b0 or b6 or b7, so just checking
* only those registers
*/
switch (p->ainsn.target_br_reg) {
case 0:
if ((regs->b0 == bundle_addr) ||
(regs->b0 == bundle_addr + 0x10)) {
regs->b0 = (regs->b0 - bundle_addr) +
resume_addr;
}
break;
case 6:
if ((regs->b6 == bundle_addr) ||
(regs->b6 == bundle_addr + 0x10)) {
regs->b6 = (regs->b6 - bundle_addr) +
resume_addr;
}
break;
case 7:
if ((regs->b7 == bundle_addr) ||
(regs->b7 == bundle_addr + 0x10)) {
regs->b7 = (regs->b7 - bundle_addr) +
resume_addr;
}
break;
} /* end switch */
}
goto turn_ss_off;
}

ia64_psr(regs)->ss = 0;
if (slot == 2) {
if (regs->cr_iip == bundle_addr + 0x10) {
regs->cr_iip = resume_addr + 0x10;
}
} else {
if (regs->cr_iip == bundle_addr) {
regs->cr_iip = resume_addr;
}
}

turn_ss_off:
/* Turn off Single Step bit */
ia64_psr(regs)->ss = 0;
}

static void prepare_ss(struct kprobe *p, struct pt_regs *regs)
Expand Down
17 changes: 16 additions & 1 deletion include/asm-ia64/kprobes.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,17 @@ typedef struct _bundle {

#define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)pentry

#define SLOT0_OPCODE_SHIFT (37)
#define SLOT1_p1_OPCODE_SHIFT (37 - (64-46))
#define SLOT2_OPCODE_SHIFT (37)

#define INDIRECT_CALL_OPCODE (1)
#define IP_RELATIVE_CALL_OPCODE (5)
#define IP_RELATIVE_BRANCH_OPCODE (4)
#define IP_RELATIVE_PREDICT_OPCODE (7)
#define LONG_BRANCH_OPCODE (0xC)
#define LONG_CALL_OPCODE (0xD)

typedef struct kprobe_opcode {
bundle_t bundle;
} kprobe_opcode_t;
Expand All @@ -55,8 +66,12 @@ struct fnptr {

/* Architecture specific copy of original instruction*/
struct arch_specific_insn {
/* copy of the original instruction */
/* copy of the instruction to be emulated */
kprobe_opcode_t insn;
#define INST_FLAG_FIX_RELATIVE_IP_ADDR 1
#define INST_FLAG_FIX_BRANCH_REG 2
unsigned long inst_flag;
unsigned short target_br_reg;
};

/* ia64 does not need this */
Expand Down

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