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linux/arch/ia64/kernel/kprobes.c
Anil S Keshavamurthy 852caccc89 [PATCH] Kprobes/ia64: temporary disarming of reentrant probe 
This patch includes IA64 architecture specific changes(ported form i386) to
support temporary disarming on reentrancy of probes.

In case of reentrancy we single step without calling user handler.

Signed-of-by: Anil S Keshavamurth <anil.s.keshavamurthy@intel.com>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 09:45:25 -07:00

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/*
* Kernel Probes (KProbes)
* arch/ia64/kernel/kprobes.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* 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/config.h>
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/preempt.h>
#include <linux/moduleloader.h>
#include <asm/pgtable.h>
#include <asm/kdebug.h>
extern void jprobe_inst_return(void);
/* kprobe_status settings */
#define KPROBE_HIT_ACTIVE 0x00000001
#define KPROBE_HIT_SS 0x00000002
static struct kprobe *current_kprobe, *kprobe_prev;
static unsigned long kprobe_status, kprobe_status_prev;
static struct pt_regs jprobe_saved_regs;
enum instruction_type {A, I, M, F, B, L, X, u};
static enum instruction_type bundle_encoding[32][3] = {
{ M, I, I }, /* 00 */
{ M, I, I }, /* 01 */
{ M, I, I }, /* 02 */
{ M, I, I }, /* 03 */
{ M, L, X }, /* 04 */
{ M, L, X }, /* 05 */
{ u, u, u }, /* 06 */
{ u, u, u }, /* 07 */
{ M, M, I }, /* 08 */
{ M, M, I }, /* 09 */
{ M, M, I }, /* 0A */
{ M, M, I }, /* 0B */
{ M, F, I }, /* 0C */
{ M, F, I }, /* 0D */
{ M, M, F }, /* 0E */
{ M, M, F }, /* 0F */
{ M, I, B }, /* 10 */
{ M, I, B }, /* 11 */
{ M, B, B }, /* 12 */
{ M, B, B }, /* 13 */
{ u, u, u }, /* 14 */
{ u, u, u }, /* 15 */
{ B, B, B }, /* 16 */
{ B, B, B }, /* 17 */
{ M, M, B }, /* 18 */
{ M, M, B }, /* 19 */
{ u, u, u }, /* 1A */
{ u, u, u }, /* 1B */
{ M, F, B }, /* 1C */
{ M, F, B }, /* 1D */
{ u, u, u }, /* 1E */
{ u, u, u }, /* 1F */
};
/*
* 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)
{
p->ainsn.inst_flag = 0;
p->ainsn.target_br_reg = 0;
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
* on which we are inserting kprobe is supported.
* Returns 0 if supported
* Returns -EINVAL if unsupported
*/
static int unsupported_inst(uint template, uint slot, uint major_opcode,
unsigned long kprobe_inst, struct kprobe *p)
{
unsigned long addr = (unsigned long)p->addr;
if (bundle_encoding[template][slot] == I) {
switch (major_opcode) {
case 0x0: //I_UNIT_MISC_OPCODE:
/*
* 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;
}
}
}
return 0;
}
/*
* 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 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)) {
/* Integere 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)) {
/* Integere 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 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 iff !is_cmp_ctype_unc_inst
* because for cmp instruction with ctype equal to unc,
* which is a special instruction always needs to be
* executed regradless of qp
*/
if (!is_cmp_ctype_unc_inst(template, slot, major_opcode, kprobe_inst))
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;
}
/*
* 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;
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;
}
}
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;
}
static inline void save_previous_kprobe(void)
{
kprobe_prev = current_kprobe;
kprobe_status_prev = kprobe_status;
}
static inline void restore_previous_kprobe(void)
{
current_kprobe = kprobe_prev;
kprobe_status = kprobe_status_prev;
}
static inline void set_current_kprobe(struct kprobe *p)
{
current_kprobe = p;
}
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);
if (unsupported_inst(template, slot, major_opcode, kprobe_inst, p))
return -EINVAL;
prepare_break_inst(template, slot, major_opcode, kprobe_inst, p);
return 0;
}
void arch_arm_kprobe(struct kprobe *p)
{
unsigned long addr = (unsigned long)p->addr;
unsigned long arm_addr = addr & ~0xFULL;
memcpy((char *)arm_addr, &p->ainsn.insn.bundle, sizeof(bundle_t));
flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
}
void arch_disarm_kprobe(struct kprobe *p)
{
unsigned long addr = (unsigned long)p->addr;
unsigned long arm_addr = addr & ~0xFULL;
/* p->opcode contains the original unaltered bundle */
memcpy((char *) arm_addr, (char *) &p->opcode.bundle, sizeof(bundle_t));
flush_icache_range(arm_addr, arm_addr + sizeof(bundle_t));
}
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. 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_addr = ((unsigned long) (&p->opcode.bundle)) & ~0xFULL;
unsigned long resume_addr = (unsigned long)p->addr & ~0xFULL;
unsigned long template;
int slot = ((unsigned long)p->addr & 0xf);
template = p->opcode.bundle.quad0.template;
if (slot == 1 && bundle_encoding[template][1] == L)
slot = 2;
if (p->ainsn.inst_flag) {
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 prepare_ss(struct kprobe *p, struct pt_regs *regs)
{
unsigned long bundle_addr = (unsigned long) &p->opcode.bundle;
unsigned long slot = (unsigned long)p->addr & 0xf;
/* Update instruction pointer (IIP) and slot number (IPSR.ri) */
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 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);
preempt_disable();
/* Handle recursion cases */
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
if (kprobe_status == KPROBE_HIT_SS) {
unlock_kprobes();
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();
set_current_kprobe(p);
p->nmissed++;
prepare_ss(p, regs);
kprobe_status = KPROBE_REENTER;
return 1;
} else if (args->err == __IA64_BREAK_JPROBE) {
/*
* jprobe instrumented function just completed
*/
p = current_kprobe;
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;
}
} else {
/* Not our break */
goto no_kprobe;
}
}
lock_kprobes();
p = get_kprobe(addr);
if (!p) {
unlock_kprobes();
goto no_kprobe;
}
kprobe_status = KPROBE_HIT_ACTIVE;
set_current_kprobe(p);
if (p->pre_handler && p->pre_handler(p, regs))
/*
* Our pre-handler is specifically requesting that we just
* do a return. This is handling the case where the
* pre-handler is really our special jprobe pre-handler.
*/
return 1;
ss_probe:
prepare_ss(p, regs);
kprobe_status = KPROBE_HIT_SS;
return 1;
no_kprobe:
preempt_enable_no_resched();
return ret;
}
static int post_kprobes_handler(struct pt_regs *regs)
{
if (!kprobe_running())
return 0;
if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
kprobe_status = KPROBE_HIT_SSDONE;
current_kprobe->post_handler(current_kprobe, regs, 0);
}
resume_execution(current_kprobe, regs);
/*Restore back the original saved kprobes variables and continue. */
if (kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe();
goto out;
}
unlock_kprobes();
out:
preempt_enable_no_resched();
return 1;
}
static int kprobes_fault_handler(struct pt_regs *regs, int trapnr)
{
if (!kprobe_running())
return 0;
if (current_kprobe->fault_handler &&
current_kprobe->fault_handler(current_kprobe, regs, trapnr))
return 1;
if (kprobe_status & KPROBE_HIT_SS) {
resume_execution(current_kprobe, regs);
unlock_kprobes();
preempt_enable_no_resched();
}
return 0;
}
int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
void *data)
{
struct die_args *args = (struct die_args *)data;
switch(val) {
case DIE_BREAK:
if (pre_kprobes_handler(args))
return NOTIFY_STOP;
break;
case DIE_SS:
if (post_kprobes_handler(args->regs))
return NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
if (kprobes_fault_handler(args->regs, args->trapnr))
return NOTIFY_STOP;
default:
break;
}
return NOTIFY_DONE;
}
int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
/* save architectural state */
jprobe_saved_regs = *regs;
/* after rfi, execute the jprobe instrumented function */
regs->cr_iip = addr & ~0xFULL;
ia64_psr(regs)->ri = addr & 0xf;
regs->r1 = ((struct fnptr *)(jp->entry))->gp;
/*
* fix the return address to our jprobe_inst_return() function
* in the jprobes.S file
*/
regs->b0 = ((struct fnptr *)(jprobe_inst_return))->ip;
return 1;
}
int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
*regs = jprobe_saved_regs;
return 1;
}
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