kernel-fxtec-pro1x/arch/ia64/kernel/kprobes.c

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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>
#include <asm/sections.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;
}
}
/* Returns non-zero if the addr is in the Interrupt Vector Table */
static inline int in_ivt_functions(unsigned long addr)
{
return (addr >= (unsigned long)__start_ivt_text
&& addr < (unsigned long)__end_ivt_text);
}
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;
}
if (in_ivt_functions(addr)) {
printk(KERN_WARNING "Kprobes can't be inserted inside "
"IVT functions at 0x%lx\n", addr);
return -EINVAL;
}
if (slot == 1 && bundle_encoding[template][1] != L) {
printk(KERN_WARNING "Inserting kprobes on slot #1 "
"is not supported\n");
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;
}
[PATCH] Return probe redesign: ia64 specific implementation The following patch implements function return probes for ia64 using the revised design. With this new design we no longer need to do some of the odd hacks previous required on the last ia64 return probe port that I sent out for comments. Note that this new implementation still does not resolve the problem noted by Keith Owens where backtrace data is lost after a return probe is hit. Changes include: * Addition of kretprobe_trampoline to act as a dummy function for instrumented functions to return to, and for the return probe infrastructure to place a kprobe on on, gaining control so that the return probe handler can be called, and so that the instruction pointer can be moved back to the original return address. * Addition of arch_init(), allowing a kprobe to be registered on kretprobe_trampoline * Addition of trampoline_probe_handler() which is used as the pre_handler for the kprobe inserted on kretprobe_implementation. This is the function that handles the details for calling the return probe handler function and returning control back at the original return address * Addition of arch_prepare_kretprobe() which is setup as the pre_handler for a kprobe registered at the beginning of the target function by kernel/kprobes.c so that a return probe instance can be setup when a caller enters the target function. (A return probe instance contains all the needed information for trampoline_probe_handler to do it's job.) * Hooks added to the exit path of a task so that we can cleanup any left-over return probe instances (i.e. if a task dies while inside a targeted function then the return probe instance was reserved at the beginning of the function but the function never returns so we need to mark the instance as unused.) Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 16:17:12 -06:00
static void kretprobe_trampoline(void)
{
}
/*
* At this point the target function has been tricked into
* returning into our trampoline. Lookup the associated instance
* and then:
* - call the handler function
* - cleanup by marking the instance as unused
* - long jump back to the original return address
*/
int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe_instance *ri = NULL;
struct hlist_head *head;
struct hlist_node *node, *tmp;
unsigned long orig_ret_address = 0;
unsigned long trampoline_address =
((struct fnptr *)kretprobe_trampoline)->ip;
head = kretprobe_inst_table_head(current);
/*
* It is possible to have multiple instances associated with a given
* task either because an multiple functions in the call path
* have a return probe installed on them, and/or more then one return
* return probe was registered for a target function.
*
* We can handle this because:
* - instances are always inserted at the head of the list
* - when multiple return probes are registered for the same
* function, the first instance's ret_addr will point to the
* real return address, and all the rest will point to
* kretprobe_trampoline
*/
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
if (ri->rp && ri->rp->handler)
ri->rp->handler(ri, regs);
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri);
if (orig_ret_address != trampoline_address)
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
}
BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
regs->cr_iip = orig_ret_address;
unlock_kprobes();
preempt_enable_no_resched();
/*
* By returning a non-zero value, we are telling
* kprobe_handler() that we have handled unlocking
* and re-enabling preemption.
*/
return 1;
}
void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
{
struct kretprobe_instance *ri;
if ((ri = get_free_rp_inst(rp)) != NULL) {
ri->rp = rp;
ri->task = current;
ri->ret_addr = (kprobe_opcode_t *)regs->b0;
/* Replace the return addr with trampoline addr */
regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip;
add_rp_inst(ri);
} else {
rp->nmissed++;
}
}
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
[PATCH] Return probe redesign: ia64 specific implementation The following patch implements function return probes for ia64 using the revised design. With this new design we no longer need to do some of the odd hacks previous required on the last ia64 return probe port that I sent out for comments. Note that this new implementation still does not resolve the problem noted by Keith Owens where backtrace data is lost after a return probe is hit. Changes include: * Addition of kretprobe_trampoline to act as a dummy function for instrumented functions to return to, and for the return probe infrastructure to place a kprobe on on, gaining control so that the return probe handler can be called, and so that the instruction pointer can be moved back to the original return address. * Addition of arch_init(), allowing a kprobe to be registered on kretprobe_trampoline * Addition of trampoline_probe_handler() which is used as the pre_handler for the kprobe inserted on kretprobe_implementation. This is the function that handles the details for calling the return probe handler function and returning control back at the original return address * Addition of arch_prepare_kretprobe() which is setup as the pre_handler for a kprobe registered at the beginning of the target function by kernel/kprobes.c so that a return probe instance can be setup when a caller enters the target function. (A return probe instance contains all the needed information for trampoline_probe_handler to do it's job.) * Hooks added to the exit path of a task so that we can cleanup any left-over return probe instances (i.e. if a task dies while inside a targeted function then the return probe instance was reserved at the beginning of the function but the function never returns so we need to mark the instance as unused.) Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 16:17:12 -06:00
* do a return. This is used for both the jprobe pre-handler
* and the kretprobe trampoline
*/
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;
}
[PATCH] Return probe redesign: ia64 specific implementation The following patch implements function return probes for ia64 using the revised design. With this new design we no longer need to do some of the odd hacks previous required on the last ia64 return probe port that I sent out for comments. Note that this new implementation still does not resolve the problem noted by Keith Owens where backtrace data is lost after a return probe is hit. Changes include: * Addition of kretprobe_trampoline to act as a dummy function for instrumented functions to return to, and for the return probe infrastructure to place a kprobe on on, gaining control so that the return probe handler can be called, and so that the instruction pointer can be moved back to the original return address. * Addition of arch_init(), allowing a kprobe to be registered on kretprobe_trampoline * Addition of trampoline_probe_handler() which is used as the pre_handler for the kprobe inserted on kretprobe_implementation. This is the function that handles the details for calling the return probe handler function and returning control back at the original return address * Addition of arch_prepare_kretprobe() which is setup as the pre_handler for a kprobe registered at the beginning of the target function by kernel/kprobes.c so that a return probe instance can be setup when a caller enters the target function. (A return probe instance contains all the needed information for trampoline_probe_handler to do it's job.) * Hooks added to the exit path of a task so that we can cleanup any left-over return probe instances (i.e. if a task dies while inside a targeted function then the return probe instance was reserved at the beginning of the function but the function never returns so we need to mark the instance as unused.) Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 16:17:12 -06:00
static struct kprobe trampoline_p = {
.pre_handler = trampoline_probe_handler
};
int __init arch_init(void)
{
trampoline_p.addr =
(kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip;
return register_kprobe(&trampoline_p);
}