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linuxdebug/arch/ia64/kernel/kprobes.c

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null pointer error
2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Kernel Probes (KProbes)
* arch/ia64/kernel/kprobes.c
*
* Copyright (C) IBM Corporation, 2002, 2004
* Copyright (C) Intel Corporation, 2005
*
* 2005-Apr Rusty Lynch <rusty.lynch@intel.com> and Anil S Keshavamurthy
* <anil.s.keshavamurthy@intel.com> adapted from i386
*/
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/preempt.h>
#include <linux/extable.h>
#include <linux/kdebug.h>
#include <linux/pgtable.h>
#include <asm/sections.h>
#include <asm/exception.h>
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}};
enum instruction_type {A, I, M, F, B, L, X, u};
static enum instruction_type bundle_encoding[32][3] = {
[0x00] = { M, I, I },
[0x01] = { M, I, I },
[0x02] = { M, I, I },
[0x03] = { M, I, I },
[0x04] = { M, L, X },
[0x05] = { M, L, X },
[0x06] = { u, u, u },
[0x07] = { u, u, u },
[0x08] = { M, M, I },
[0x09] = { M, M, I },
[0x0A] = { M, M, I },
[0x0B] = { M, M, I },
[0x0C] = { M, F, I },
[0x0D] = { M, F, I },
[0x0E] = { M, M, F },
[0x0F] = { M, M, F },
[0x10] = { M, I, B },
[0x11] = { M, I, B },
[0x12] = { M, B, B },
[0x13] = { M, B, B },
[0x14] = { u, u, u },
[0x15] = { u, u, u },
[0x16] = { B, B, B },
[0x17] = { B, B, B },
[0x18] = { M, M, B },
[0x19] = { M, M, B },
[0x1A] = { u, u, u },
[0x1B] = { u, u, u },
[0x1C] = { M, F, B },
[0x1D] = { M, F, B },
[0x1E] = { u, u, u },
[0x1F] = { u, u, u },
};
/* Insert a long branch code */
static void __kprobes set_brl_inst(void *from, void *to)
{
s64 rel = ((s64) to - (s64) from) >> 4;
bundle_t *brl;
brl = (bundle_t *) ((u64) from & ~0xf);
brl->quad0.template = 0x05; /* [MLX](stop) */
brl->quad0.slot0 = NOP_M_INST; /* nop.m 0x0 */
brl->quad0.slot1_p0 = ((rel >> 20) & 0x7fffffffff) << 2;
brl->quad1.slot1_p1 = (((rel >> 20) & 0x7fffffffff) << 2) >> (64 - 46);
/* brl.cond.sptk.many.clr rel<<4 (qp=0) */
brl->quad1.slot2 = BRL_INST(rel >> 59, rel & 0xfffff);
}
/*
* In this function we check to see if the instruction
* is IP relative instruction and update the kprobe
* inst flag accordingly
*/
static void __kprobes update_kprobe_inst_flag(uint template, uint slot,
uint major_opcode,
unsigned long kprobe_inst,
struct kprobe *p)
{
p->ainsn.inst_flag = 0;
p->ainsn.target_br_reg = 0;
p->ainsn.slot = slot;
/* Check for Break instruction
* Bits 37:40 Major opcode to be zero
* Bits 27:32 X6 to be zero
* Bits 32:35 X3 to be zero
*/
if ((!major_opcode) && (!((kprobe_inst >> 27) & 0x1FF)) ) {
/* is a break instruction */
p->ainsn.inst_flag |= INST_FLAG_BREAK_INST;
return;
}
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;
}
/*
* In this function we check to see if the instruction
* (qp) cmpx.crel.ctype p1,p2=r2,r3
* on which we are inserting kprobe is cmp instruction
* with ctype as unc.
*/
static uint __kprobes is_cmp_ctype_unc_inst(uint template, uint slot,
uint major_opcode,
unsigned long kprobe_inst)
{
cmp_inst_t cmp_inst;
uint ctype_unc = 0;
if (!((bundle_encoding[template][slot] == I) ||
(bundle_encoding[template][slot] == M)))
goto out;
if (!((major_opcode == 0xC) || (major_opcode == 0xD) ||
(major_opcode == 0xE)))
goto out;
cmp_inst.l = kprobe_inst;
if ((cmp_inst.f.x2 == 0) || (cmp_inst.f.x2 == 1)) {
/* Integer compare - Register Register (A6 type)*/
if ((cmp_inst.f.tb == 0) && (cmp_inst.f.ta == 0)
&&(cmp_inst.f.c == 1))
ctype_unc = 1;
} else if ((cmp_inst.f.x2 == 2)||(cmp_inst.f.x2 == 3)) {
/* Integer compare - Immediate Register (A8 type)*/
if ((cmp_inst.f.ta == 0) &&(cmp_inst.f.c == 1))
ctype_unc = 1;
}
out:
return ctype_unc;
}
/*
* In this function we check to see if the instruction
* on which we are inserting kprobe is supported.
* Returns qp value if supported
* Returns -EINVAL if unsupported
*/
static int __kprobes unsupported_inst(uint template, uint slot,
uint major_opcode,
unsigned long kprobe_inst,
unsigned long addr)
{
int qp;
qp = kprobe_inst & 0x3f;
if (is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst)) {
if (slot == 1 && qp) {
printk(KERN_WARNING "Kprobes on cmp unc "
"instruction on slot 1 at <0x%lx> "
"is not supported\n", addr);
return -EINVAL;
}
qp = 0;
}
else if (bundle_encoding[template][slot] == I) {
if (major_opcode == 0) {
/*
* Check for Integer speculation instruction
* - Bit 33-35 to be equal to 0x1
*/
if (((kprobe_inst >> 33) & 0x7) == 1) {
printk(KERN_WARNING
"Kprobes on speculation inst at <0x%lx> not supported\n",
addr);
return -EINVAL;
}
/*
* IP relative mov instruction
* - Bit 27-35 to be equal to 0x30
*/
if (((kprobe_inst >> 27) & 0x1FF) == 0x30) {
printk(KERN_WARNING
"Kprobes on \"mov r1=ip\" at <0x%lx> not supported\n",
addr);
return -EINVAL;
}
}
else if ((major_opcode == 5) && !(kprobe_inst & (0xFUl << 33)) &&
(kprobe_inst & (0x1UL << 12))) {
/* test bit instructions, tbit,tnat,tf
* bit 33-36 to be equal to 0
* bit 12 to be equal to 1
*/
if (slot == 1 && qp) {
printk(KERN_WARNING "Kprobes on test bit "
"instruction on slot at <0x%lx> "
"is not supported\n", addr);
return -EINVAL;
}
qp = 0;
}
}
else if (bundle_encoding[template][slot] == B) {
if (major_opcode == 7) {
/* IP-Relative Predict major code is 7 */
printk(KERN_WARNING "Kprobes on IP-Relative"
"Predict is not supported\n");
return -EINVAL;
}
else if (major_opcode == 2) {
/* Indirect Predict, major code is 2
* bit 27-32 to be equal to 10 or 11
*/
int x6=(kprobe_inst >> 27) & 0x3F;
if ((x6 == 0x10) || (x6 == 0x11)) {
printk(KERN_WARNING "Kprobes on "
"Indirect Predict is not supported\n");
return -EINVAL;
}
}
}
/* kernel does not use float instruction, here for safety kprobe
* will judge whether it is fcmp/flass/float approximation instruction
*/
else if (unlikely(bundle_encoding[template][slot] == F)) {
if ((major_opcode == 4 || major_opcode == 5) &&
(kprobe_inst & (0x1 << 12))) {
/* fcmp/fclass unc instruction */
if (slot == 1 && qp) {
printk(KERN_WARNING "Kprobes on fcmp/fclass "
"instruction on slot at <0x%lx> "
"is not supported\n", addr);
return -EINVAL;
}
qp = 0;
}
if ((major_opcode == 0 || major_opcode == 1) &&
(kprobe_inst & (0x1UL << 33))) {
/* float Approximation instruction */
if (slot == 1 && qp) {
printk(KERN_WARNING "Kprobes on float Approx "
"instr at <0x%lx> is not supported\n",
addr);
return -EINVAL;
}
qp = 0;
}
}
return qp;
}
/*
* In this function we override the bundle with
* the break instruction at the given slot.
*/
static void __kprobes prepare_break_inst(uint template, uint slot,
uint major_opcode,
unsigned long kprobe_inst,
struct kprobe *p,
int qp)
{
unsigned long break_inst = BREAK_INST;
bundle_t *bundle = &p->opcode.bundle;
/*
* Copy the original kprobe_inst qualifying predicate(qp)
* to the break instruction
*/
break_inst |= qp;
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;
}
/*
* 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 void __kprobes 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;
break;
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;
break;
}
}
/* Returns non-zero if the addr is in the Interrupt Vector Table */
static int __kprobes in_ivt_functions(unsigned long addr)
{
return (addr >= (unsigned long)__start_ivt_text
&& addr < (unsigned long)__end_ivt_text);
}
static int __kprobes 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;
}
if (in_ivt_functions(addr)) {
printk(KERN_WARNING "Kprobes can't be inserted inside "
"IVT functions at 0x%lx\n", addr);
return -EINVAL;
}
return 0;
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
unsigned int i;
i = atomic_add_return(1, &kcb->prev_kprobe_index);
kcb->prev_kprobe[i-1].kp = kprobe_running();
kcb->prev_kprobe[i-1].status = kcb->kprobe_status;
}
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
unsigned int i;
i = atomic_read(&kcb->prev_kprobe_index);
__this_cpu_write(current_kprobe, kcb->prev_kprobe[i-1].kp);
kcb->kprobe_status = kcb->prev_kprobe[i-1].status;
atomic_sub(1, &kcb->prev_kprobe_index);
}
static void __kprobes set_current_kprobe(struct kprobe *p,
struct kprobe_ctlblk *kcb)
{
__this_cpu_write(current_kprobe, p);
}
void __kretprobe_trampoline(void)
{
}
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
regs->cr_iip = __kretprobe_trampoline_handler(regs, NULL);
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we don't want the post_handler
* to run (and have re-enabled preemption)
*/
return 1;
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->b0;
ri->fp = NULL;
/* Replace the return addr with trampoline addr */
regs->b0 = (unsigned long)dereference_function_descriptor(__kretprobe_trampoline);
}
/* Check the instruction in the slot is break */
static int __kprobes __is_ia64_break_inst(bundle_t *bundle, uint slot)
{
unsigned int major_opcode;
unsigned int template = bundle->quad0.template;
unsigned long kprobe_inst;
/* 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 probe instruction at given slot*/
get_kprobe_inst(bundle, slot, &kprobe_inst, &major_opcode);
/* For break instruction,
* Bits 37:40 Major opcode to be zero
* Bits 27:32 X6 to be zero
* Bits 32:35 X3 to be zero
*/
if (major_opcode || ((kprobe_inst >> 27) & 0x1FF)) {
/* Not a break instruction */
return 0;
}
/* Is a break instruction */
return 1;
}
/*
* In this function, we check whether the target bundle modifies IP or
* it triggers an exception. If so, it cannot be boostable.
*/
static int __kprobes can_boost(bundle_t *bundle, uint slot,
unsigned long bundle_addr)
{
unsigned int template = bundle->quad0.template;
do {
if (search_exception_tables(bundle_addr + slot) ||
__is_ia64_break_inst(bundle, slot))
return 0; /* exception may occur in this bundle*/
} while ((++slot) < 3);
template &= 0x1e;
if (template >= 0x10 /* including B unit */ ||
template == 0x04 /* including X unit */ ||
template == 0x06) /* undefined */
return 0;
return 1;
}
/* Prepare long jump bundle and disables other boosters if need */
static void __kprobes prepare_booster(struct kprobe *p)
{
unsigned long addr = (unsigned long)p->addr & ~0xFULL;
unsigned int slot = (unsigned long)p->addr & 0xf;
struct kprobe *other_kp;
if (can_boost(&p->ainsn.insn[0].bundle, slot, addr)) {
set_brl_inst(&p->ainsn.insn[1].bundle, (bundle_t *)addr + 1);
p->ainsn.inst_flag |= INST_FLAG_BOOSTABLE;
}
/* disables boosters in previous slots */
for (; addr < (unsigned long)p->addr; addr++) {
other_kp = get_kprobe((void *)addr);
if (other_kp)
other_kp->ainsn.inst_flag &= ~INST_FLAG_BOOSTABLE;
}
}
int __kprobes 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;
int qp;
bundle = &((kprobe_opcode_t *)kprobe_addr)->bundle;
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);
qp = unsupported_inst(template, slot, major_opcode, kprobe_inst, addr);
if (qp < 0)
return -EINVAL;
p->ainsn.insn = get_insn_slot();
if (!p->ainsn.insn)
return -ENOMEM;
memcpy(&p->opcode, kprobe_addr, sizeof(kprobe_opcode_t));
memcpy(p->ainsn.insn, kprobe_addr, sizeof(kprobe_opcode_t));
prepare_break_inst(template, slot, major_opcode, kprobe_inst, p, qp);
prepare_booster(p);
return 0;
}
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
unsigned long arm_addr;
bundle_t *src, *dest;
arm_addr = ((unsigned long)p->addr) & ~0xFUL;
dest = &((kprobe_opcode_t *)arm_addr)->bundle;
src = &p->opcode.bundle;
flush_icache_range((unsigned long)p->ainsn.insn,
(unsigned long)p->ainsn.insn +
sizeof(kprobe_opcode_t) * MAX_INSN_SIZE);
switch (p->ainsn.slot) {
case 0:
dest->quad0.slot0 = src->quad0.slot0;
break;
case 1:
dest->quad1.slot1_p1 = src->quad1.slot1_p1;
break;
case 2:
dest->quad1.slot2 = src->quad1.slot2;
break;
}
flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
}
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
unsigned long arm_addr;
bundle_t *src, *dest;
arm_addr = ((unsigned long)p->addr) & ~0xFUL;
dest = &((kprobe_opcode_t *)arm_addr)->bundle;
/* p->ainsn.insn contains the original unaltered kprobe_opcode_t */
src = &p->ainsn.insn->bundle;
switch (p->ainsn.slot) {
case 0:
dest->quad0.slot0 = src->quad0.slot0;
break;
case 1:
dest->quad1.slot1_p1 = src->quad1.slot1_p1;
break;
case 2:
dest->quad1.slot2 = src->quad1.slot2;
break;
}
flush_icache_range(arm_addr, arm_addr + sizeof(kprobe_opcode_t));
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
if (p->ainsn.insn) {
free_insn_slot(p->ainsn.insn,
p->ainsn.inst_flag & INST_FLAG_BOOSTABLE);
p->ainsn.insn = NULL;
}
}
/*
* 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. 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 __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
{
unsigned long bundle_addr = (unsigned long) (&p->ainsn.insn->bundle);
unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
unsigned long template;
int slot = ((unsigned long)p->addr & 0xf);
template = p->ainsn.insn->bundle.quad0.template;
if (slot == 1 && bundle_encoding[template][1] == L)
slot = 2;
if (p->ainsn.inst_flag & ~INST_FLAG_BOOSTABLE) {
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;
}
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 __kprobes prepare_ss(struct kprobe *p, struct pt_regs *regs)
{
unsigned long bundle_addr = (unsigned long) &p->ainsn.insn->bundle;
unsigned long slot = (unsigned long)p->addr & 0xf;
/* single step inline if break instruction */
if (p->ainsn.inst_flag == INST_FLAG_BREAK_INST)
regs->cr_iip = (unsigned long)p->addr & ~0xFULL;
else
regs->cr_iip = bundle_addr & ~0xFULL;
if (slot > 2)
slot = 0;
ia64_psr(regs)->ri = slot;
/* turn on single stepping */
ia64_psr(regs)->ss = 1;
}
static int __kprobes is_ia64_break_inst(struct pt_regs *regs)
{
unsigned int slot = ia64_psr(regs)->ri;
unsigned long *kprobe_addr = (unsigned long *)regs->cr_iip;
bundle_t bundle;
memcpy(&bundle, kprobe_addr, sizeof(bundle_t));
return __is_ia64_break_inst(&bundle, slot);
}
static int __kprobes pre_kprobes_handler(struct die_args *args)
{
struct kprobe *p;
int ret = 0;
struct pt_regs *regs = args->regs;
kprobe_opcode_t *addr = (kprobe_opcode_t *)instruction_pointer(regs);
struct kprobe_ctlblk *kcb;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
/* Handle recursion cases */
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
if ((kcb->kprobe_status == KPROBE_HIT_SS) &&
(p->ainsn.inst_flag == INST_FLAG_BREAK_INST)) {
ia64_psr(regs)->ss = 0;
goto no_kprobe;
}
/* We have reentered the pre_kprobe_handler(), since
* another probe was hit while within the handler.
* We here save the original kprobes variables and
* just single step on the instruction of the new probe
* without calling any user handlers.
*/
save_previous_kprobe(kcb);
set_current_kprobe(p, kcb);
kprobes_inc_nmissed_count(p);
prepare_ss(p, regs);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else if (!is_ia64_break_inst(regs)) {
/* The breakpoint instruction was removed by
* another cpu right after we hit, no further
* handling of this interrupt is appropriate
*/
ret = 1;
goto no_kprobe;
} else {
/* Not our break */
goto no_kprobe;
}
}
p = get_kprobe(addr);
if (!p) {
if (!is_ia64_break_inst(regs)) {
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
* either a probepoint or a debugger breakpoint
* at this address. In either case, no further
* handling of this interrupt is appropriate.
*/
ret = 1;
}
/* Not one of our break, let kernel handle it */
goto no_kprobe;
}
set_current_kprobe(p, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
if (p->pre_handler && p->pre_handler(p, regs)) {
reset_current_kprobe();
preempt_enable_no_resched();
return 1;
}
#if !defined(CONFIG_PREEMPTION)
if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) {
/* Boost up -- we can execute copied instructions directly */
ia64_psr(regs)->ri = p->ainsn.slot;
regs->cr_iip = (unsigned long)&p->ainsn.insn->bundle & ~0xFULL;
/* turn single stepping off */
ia64_psr(regs)->ss = 0;
reset_current_kprobe();
preempt_enable_no_resched();
return 1;
}
#endif
prepare_ss(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;
no_kprobe:
preempt_enable_no_resched();
return ret;
}
static int __kprobes post_kprobes_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (!cur)
return 0;
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
}
resume_execution(cur, regs);
/*Restore back the original saved kprobes variables and continue. */
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
goto out;
}
reset_current_kprobe();
out:
preempt_enable_no_resched();
return 1;
}
int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
switch(kcb->kprobe_status) {
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe and the instruction pointer points back to
* the probe address and allow the page fault handler
* to continue as a normal page fault.
*/
regs->cr_iip = ((unsigned long)cur->addr) & ~0xFULL;
ia64_psr(regs)->ri = ((unsigned long)cur->addr) & 0xf;
if (kcb->kprobe_status == KPROBE_REENTER)
restore_previous_kprobe(kcb);
else
reset_current_kprobe();
preempt_enable_no_resched();
break;
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
/*
* In case the user-specified fault handler returned
* zero, try to fix up.
*/
if (ia64_done_with_exception(regs))
return 1;
/*
* Let ia64_do_page_fault() fix it.
*/
break;
default:
break;
}
return 0;
}
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
if (args->regs && user_mode(args->regs))
return ret;
switch(val) {
case DIE_BREAK:
/* err is break number from ia64_bad_break() */
if ((args->err >> 12) == (__IA64_BREAK_KPROBE >> 12)
|| args->err == 0)
if (pre_kprobes_handler(args))
ret = NOTIFY_STOP;
break;
case DIE_FAULT:
/* err is vector number from ia64_fault() */
if (args->err == 36)
if (post_kprobes_handler(args->regs))
ret = NOTIFY_STOP;
break;
default:
break;
}
return ret;
}
static struct kprobe trampoline_p = {
.pre_handler = trampoline_probe_handler
};
int __init arch_init_kprobes(void)
{
trampoline_p.addr =
dereference_function_descriptor(__kretprobe_trampoline);
return register_kprobe(&trampoline_p);
}
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
if (p->addr ==
dereference_function_descriptor(__kretprobe_trampoline))
return 1;
return 0;
}