2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* Kernel Probes (KProbes)
|
|
|
|
|
* arch/i386/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
|
|
|
|
|
*
|
|
|
|
|
* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
|
|
|
|
|
* Probes initial implementation ( includes contributions from
|
|
|
|
|
* Rusty Russell).
|
|
|
|
|
* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
|
|
|
|
|
* interface to access function arguments.
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
|
|
|
|
|
* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
|
|
|
|
|
* <prasanna@in.ibm.com> added function-return probes.
|
2005-04-16 22:20:36 +00:00
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include <linux/config.h>
|
|
|
|
|
#include <linux/kprobes.h>
|
|
|
|
|
#include <linux/ptrace.h>
|
|
|
|
|
#include <linux/preempt.h>
|
2005-06-23 07:09:25 +00:00
|
|
|
#include <asm/cacheflush.h>
|
2005-04-16 22:20:36 +00:00
|
|
|
#include <asm/kdebug.h>
|
|
|
|
|
#include <asm/desc.h>
|
|
|
|
|
|
|
|
|
|
void jprobe_return_end(void);
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
|
|
|
|
|
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* returns non-zero if opcode modifies the interrupt flag.
|
|
|
|
|
*/
|
|
|
|
|
static inline int is_IF_modifier(kprobe_opcode_t opcode)
|
|
|
|
|
{
|
|
|
|
|
switch (opcode) {
|
|
|
|
|
case 0xfa: /* cli */
|
|
|
|
|
case 0xfb: /* sti */
|
|
|
|
|
case 0xcf: /* iret/iretd */
|
|
|
|
|
case 0x9d: /* popf/popfd */
|
|
|
|
|
return 1;
|
|
|
|
|
}
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
int __kprobes arch_prepare_kprobe(struct kprobe *p)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes arch_copy_kprobe(struct kprobe *p)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
|
2005-06-23 07:09:25 +00:00
|
|
|
p->opcode = *p->addr;
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes arch_arm_kprobe(struct kprobe *p)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
2005-06-23 07:09:25 +00:00
|
|
|
*p->addr = BREAKPOINT_INSTRUCTION;
|
|
|
|
|
flush_icache_range((unsigned long) p->addr,
|
|
|
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes arch_disarm_kprobe(struct kprobe *p)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
*p->addr = p->opcode;
|
2005-06-23 07:09:25 +00:00
|
|
|
flush_icache_range((unsigned long) p->addr,
|
|
|
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
|
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes arch_remove_kprobe(struct kprobe *p)
|
2005-06-23 07:09:25 +00:00
|
|
|
{
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb)
|
2005-06-23 07:09:37 +00:00
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
kcb->prev_kprobe.kp = kprobe_running();
|
|
|
|
|
kcb->prev_kprobe.status = kcb->kprobe_status;
|
|
|
|
|
kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
|
|
|
|
|
kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
|
2005-06-23 07:09:37 +00:00
|
|
|
}
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
|
2005-06-23 07:09:37 +00:00
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
|
|
|
|
|
kcb->kprobe_status = kcb->prev_kprobe.status;
|
|
|
|
|
kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
|
|
|
|
|
kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
|
2005-06-23 07:09:37 +00:00
|
|
|
}
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
|
|
|
|
|
struct kprobe_ctlblk *kcb)
|
2005-06-23 07:09:37 +00:00
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
__get_cpu_var(current_kprobe) = p;
|
|
|
|
|
kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
|
2005-06-23 07:09:37 +00:00
|
|
|
= (regs->eflags & (TF_MASK | IF_MASK));
|
|
|
|
|
if (is_IF_modifier(p->opcode))
|
2005-11-07 09:00:08 +00:00
|
|
|
kcb->kprobe_saved_eflags &= ~IF_MASK;
|
2005-06-23 07:09:37 +00:00
|
|
|
}
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
|
|
|
|
|
{
|
|
|
|
|
regs->eflags |= TF_MASK;
|
|
|
|
|
regs->eflags &= ~IF_MASK;
|
|
|
|
|
/*single step inline if the instruction is an int3*/
|
|
|
|
|
if (p->opcode == BREAKPOINT_INSTRUCTION)
|
|
|
|
|
regs->eip = (unsigned long)p->addr;
|
|
|
|
|
else
|
|
|
|
|
regs->eip = (unsigned long)&p->ainsn.insn;
|
|
|
|
|
}
|
|
|
|
|
|
2005-11-07 09:00:14 +00:00
|
|
|
/* Called with kretprobe_lock held */
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
|
|
|
|
|
struct pt_regs *regs)
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
{
|
|
|
|
|
unsigned long *sara = (unsigned long *)®s->esp;
|
2005-06-27 22:17:09 +00:00
|
|
|
struct kretprobe_instance *ri;
|
|
|
|
|
|
|
|
|
|
if ((ri = get_free_rp_inst(rp)) != NULL) {
|
|
|
|
|
ri->rp = rp;
|
|
|
|
|
ri->task = current;
|
|
|
|
|
ri->ret_addr = (kprobe_opcode_t *) *sara;
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
|
|
|
|
|
/* Replace the return addr with trampoline addr */
|
|
|
|
|
*sara = (unsigned long) &kretprobe_trampoline;
|
|
|
|
|
|
2005-06-27 22:17:09 +00:00
|
|
|
add_rp_inst(ri);
|
|
|
|
|
} else {
|
|
|
|
|
rp->nmissed++;
|
|
|
|
|
}
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
}
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
|
|
|
|
|
* remain disabled thorough out this function.
|
|
|
|
|
*/
|
2005-09-06 22:19:27 +00:00
|
|
|
static int __kprobes kprobe_handler(struct pt_regs *regs)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
struct kprobe *p;
|
|
|
|
|
int ret = 0;
|
|
|
|
|
kprobe_opcode_t *addr = NULL;
|
|
|
|
|
unsigned long *lp;
|
2005-11-07 09:00:14 +00:00
|
|
|
struct kprobe_ctlblk *kcb;
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* We don't want to be preempted for the entire
|
|
|
|
|
* duration of kprobe processing
|
|
|
|
|
*/
|
|
|
|
|
preempt_disable();
|
|
|
|
|
kcb = get_kprobe_ctlblk();
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
/* Check if the application is using LDT entry for its code segment and
|
|
|
|
|
* calculate the address by reading the base address from the LDT entry.
|
|
|
|
|
*/
|
|
|
|
|
if ((regs->xcs & 4) && (current->mm)) {
|
|
|
|
|
lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
|
|
|
|
|
+ (char *) current->mm->context.ldt);
|
|
|
|
|
addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
|
|
|
|
|
sizeof(kprobe_opcode_t));
|
|
|
|
|
} else {
|
|
|
|
|
addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
|
|
|
|
|
}
|
|
|
|
|
/* Check we're not actually recursing */
|
|
|
|
|
if (kprobe_running()) {
|
|
|
|
|
p = get_kprobe(addr);
|
|
|
|
|
if (p) {
|
2005-11-07 09:00:08 +00:00
|
|
|
if (kcb->kprobe_status == KPROBE_HIT_SS &&
|
2005-09-06 22:19:35 +00:00
|
|
|
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
|
2005-04-16 22:20:36 +00:00
|
|
|
regs->eflags &= ~TF_MASK;
|
2005-11-07 09:00:08 +00:00
|
|
|
regs->eflags |= kcb->kprobe_saved_eflags;
|
2005-04-16 22:20:36 +00:00
|
|
|
goto no_kprobe;
|
|
|
|
|
}
|
2005-06-23 07:09:37 +00:00
|
|
|
/* We have reentered the 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.
|
|
|
|
|
*/
|
2005-11-07 09:00:08 +00:00
|
|
|
save_previous_kprobe(kcb);
|
|
|
|
|
set_current_kprobe(p, regs, kcb);
|
2005-06-23 07:09:37 +00:00
|
|
|
p->nmissed++;
|
|
|
|
|
prepare_singlestep(p, regs);
|
2005-11-07 09:00:08 +00:00
|
|
|
kcb->kprobe_status = KPROBE_REENTER;
|
2005-06-23 07:09:37 +00:00
|
|
|
return 1;
|
2005-04-16 22:20:36 +00:00
|
|
|
} else {
|
2005-11-07 09:00:08 +00:00
|
|
|
p = __get_cpu_var(current_kprobe);
|
2005-04-16 22:20:36 +00:00
|
|
|
if (p->break_handler && p->break_handler(p, regs)) {
|
|
|
|
|
goto ss_probe;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
goto no_kprobe;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
p = get_kprobe(addr);
|
|
|
|
|
if (!p) {
|
|
|
|
|
if (regs->eflags & VM_MASK) {
|
|
|
|
|
/* We are in virtual-8086 mode. Return 0 */
|
|
|
|
|
goto no_kprobe;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (*addr != BREAKPOINT_INSTRUCTION) {
|
|
|
|
|
/*
|
|
|
|
|
* 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.
|
2005-09-06 22:19:34 +00:00
|
|
|
* Back up over the (now missing) int3 and run
|
|
|
|
|
* the original instruction.
|
2005-04-16 22:20:36 +00:00
|
|
|
*/
|
2005-09-06 22:19:34 +00:00
|
|
|
regs->eip -= sizeof(kprobe_opcode_t);
|
2005-04-16 22:20:36 +00:00
|
|
|
ret = 1;
|
|
|
|
|
}
|
|
|
|
|
/* Not one of ours: let kernel handle it */
|
|
|
|
|
goto no_kprobe;
|
|
|
|
|
}
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
set_current_kprobe(p, regs, kcb);
|
|
|
|
|
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
if (p->pre_handler && p->pre_handler(p, regs))
|
|
|
|
|
/* handler has already set things up, so skip ss setup */
|
|
|
|
|
return 1;
|
|
|
|
|
|
|
|
|
|
ss_probe:
|
|
|
|
|
prepare_singlestep(p, regs);
|
2005-11-07 09:00:08 +00:00
|
|
|
kcb->kprobe_status = KPROBE_HIT_SS;
|
2005-04-16 22:20:36 +00:00
|
|
|
return 1;
|
|
|
|
|
|
|
|
|
|
no_kprobe:
|
2005-11-07 09:00:14 +00:00
|
|
|
preempt_enable_no_resched();
|
2005-04-16 22:20:36 +00:00
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
/*
|
|
|
|
|
* For function-return probes, init_kprobes() establishes a probepoint
|
|
|
|
|
* here. When a retprobed function returns, this probe is hit and
|
|
|
|
|
* trampoline_probe_handler() runs, calling the kretprobe's handler.
|
|
|
|
|
*/
|
|
|
|
|
void kretprobe_trampoline_holder(void)
|
|
|
|
|
{
|
|
|
|
|
asm volatile ( ".global kretprobe_trampoline\n"
|
|
|
|
|
"kretprobe_trampoline: \n"
|
|
|
|
|
"nop\n");
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Called when we hit the probe point at kretprobe_trampoline
|
|
|
|
|
*/
|
2005-09-06 22:19:27 +00:00
|
|
|
int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
{
|
2005-06-27 22:17:09 +00:00
|
|
|
struct kretprobe_instance *ri = NULL;
|
|
|
|
|
struct hlist_head *head;
|
|
|
|
|
struct hlist_node *node, *tmp;
|
2005-11-07 09:00:14 +00:00
|
|
|
unsigned long flags, orig_ret_address = 0;
|
2005-06-27 22:17:09 +00:00
|
|
|
unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
|
2005-11-07 09:00:14 +00:00
|
|
|
spin_lock_irqsave(&kretprobe_lock, flags);
|
2005-06-27 22:17:09 +00:00
|
|
|
head = kretprobe_inst_table_head(current);
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
|
2005-06-27 22:17:09 +00:00
|
|
|
/*
|
|
|
|
|
* 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;
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
recycle_rp_inst(ri);
|
2005-06-27 22:17:09 +00:00
|
|
|
|
|
|
|
|
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;
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
}
|
2005-06-27 22:17:09 +00:00
|
|
|
|
|
|
|
|
BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
|
|
|
|
|
regs->eip = orig_ret_address;
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
reset_current_kprobe();
|
2005-11-07 09:00:14 +00:00
|
|
|
spin_unlock_irqrestore(&kretprobe_lock, flags);
|
2005-06-27 22:17:09 +00:00
|
|
|
preempt_enable_no_resched();
|
|
|
|
|
|
2005-11-07 09:00:07 +00:00
|
|
|
/*
|
|
|
|
|
* By returning a non-zero value, we are telling
|
2005-11-07 09:00:14 +00:00
|
|
|
* kprobe_handler() that we don't want the post_handler
|
|
|
|
|
* to run (and have re-enabled preemption)
|
2005-11-07 09:00:07 +00:00
|
|
|
*/
|
2005-06-27 22:17:09 +00:00
|
|
|
return 1;
|
[PATCH] kprobes: function-return probes
This patch adds function-return probes to kprobes for the i386
architecture. This enables you to establish a handler to be run when a
function returns.
1. API
Two new functions are added to kprobes:
int register_kretprobe(struct kretprobe *rp);
void unregister_kretprobe(struct kretprobe *rp);
2. Registration and unregistration
2.1 Register
To register a function-return probe, the user populates the following
fields in a kretprobe object and calls register_kretprobe() with the
kretprobe address as an argument:
kp.addr - the function's address
handler - this function is run after the ret instruction executes, but
before control returns to the return address in the caller.
maxactive - The maximum number of instances of the probed function that
can be active concurrently. For example, if the function is non-
recursive and is called with a spinlock or mutex held, maxactive = 1
should be enough. If the function is non-recursive and can never
relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
be enough. maxactive is used to determine how many kretprobe_instance
objects to allocate for this particular probed function. If maxactive <=
0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
NR_CPUS) else maxactive=NR_CPUS)
For example:
struct kretprobe rp;
rp.kp.addr = /* entrypoint address */
rp.handler = /*return probe handler */
rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
register_kretprobe(&rp);
The following field may also be of interest:
nmissed - Initialized to zero when the function-return probe is
registered, and incremented every time the probed function is entered but
there is no kretprobe_instance object available for establishing the
function-return probe (i.e., because maxactive was set too low).
2.2 Unregister
To unregiter a function-return probe, the user calls
unregister_kretprobe() with the same kretprobe object as registered
previously. If a probed function is running when the return probe is
unregistered, the function will return as expected, but the handler won't
be run.
3. Limitations
3.1 This patch supports only the i386 architecture, but patches for
x86_64 and ppc64 are anticipated soon.
3.2 Return probes operates by replacing the return address in the stack
(or in a known register, such as the lr register for ppc). This may
cause __builtin_return_address(0), when invoked from the return-probed
function, to return the address of the return-probes trampoline.
3.3 This implementation uses the "Multiprobes at an address" feature in
2.6.12-rc3-mm3.
3.4 Due to a limitation in multi-probes, you cannot currently establish
a return probe and a jprobe on the same function. A patch to remove
this limitation is being tested.
This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: Hien Nguyen <hien@us.ibm.com>
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
|
|
|
}
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
|
|
|
|
|
* Called after single-stepping. p->addr is the address of the
|
|
|
|
|
* instruction whose first byte has been replaced by the "int 3"
|
|
|
|
|
* instruction. To avoid the SMP problems that can occur when we
|
|
|
|
|
* temporarily put back the original opcode to single-step, we
|
|
|
|
|
* single-stepped a copy of the instruction. The address of this
|
|
|
|
|
* copy is p->ainsn.insn.
|
|
|
|
|
*
|
|
|
|
|
* This function prepares to return from the post-single-step
|
|
|
|
|
* interrupt. We have to fix up the stack as follows:
|
|
|
|
|
*
|
|
|
|
|
* 0) Except in the case of absolute or indirect jump or call instructions,
|
|
|
|
|
* the new eip is relative to the copied instruction. We need to make
|
|
|
|
|
* it relative to the original instruction.
|
|
|
|
|
*
|
|
|
|
|
* 1) If the single-stepped instruction was pushfl, then the TF and IF
|
|
|
|
|
* flags are set in the just-pushed eflags, and may need to be cleared.
|
|
|
|
|
*
|
|
|
|
|
* 2) If the single-stepped instruction was a call, the return address
|
|
|
|
|
* that is atop the stack is the address following the copied instruction.
|
|
|
|
|
* We need to make it the address following the original instruction.
|
|
|
|
|
*/
|
2005-11-07 09:00:08 +00:00
|
|
|
static void __kprobes resume_execution(struct kprobe *p,
|
|
|
|
|
struct pt_regs *regs, struct kprobe_ctlblk *kcb)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
unsigned long *tos = (unsigned long *)®s->esp;
|
|
|
|
|
unsigned long next_eip = 0;
|
|
|
|
|
unsigned long copy_eip = (unsigned long)&p->ainsn.insn;
|
|
|
|
|
unsigned long orig_eip = (unsigned long)p->addr;
|
|
|
|
|
|
|
|
|
|
switch (p->ainsn.insn[0]) {
|
|
|
|
|
case 0x9c: /* pushfl */
|
|
|
|
|
*tos &= ~(TF_MASK | IF_MASK);
|
2005-11-07 09:00:08 +00:00
|
|
|
*tos |= kcb->kprobe_old_eflags;
|
2005-04-16 22:20:36 +00:00
|
|
|
break;
|
2005-05-05 23:15:40 +00:00
|
|
|
case 0xc3: /* ret/lret */
|
|
|
|
|
case 0xcb:
|
|
|
|
|
case 0xc2:
|
|
|
|
|
case 0xca:
|
|
|
|
|
regs->eflags &= ~TF_MASK;
|
|
|
|
|
/* eip is already adjusted, no more changes required*/
|
|
|
|
|
return;
|
2005-04-16 22:20:36 +00:00
|
|
|
case 0xe8: /* call relative - Fix return addr */
|
|
|
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
|
|
|
break;
|
|
|
|
|
case 0xff:
|
|
|
|
|
if ((p->ainsn.insn[1] & 0x30) == 0x10) {
|
|
|
|
|
/* call absolute, indirect */
|
|
|
|
|
/* Fix return addr; eip is correct. */
|
|
|
|
|
next_eip = regs->eip;
|
|
|
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
|
|
|
} else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
|
|
|
|
|
((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
|
|
|
|
|
/* eip is correct. */
|
|
|
|
|
next_eip = regs->eip;
|
|
|
|
|
}
|
|
|
|
|
break;
|
|
|
|
|
case 0xea: /* jmp absolute -- eip is correct */
|
|
|
|
|
next_eip = regs->eip;
|
|
|
|
|
break;
|
|
|
|
|
default:
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
regs->eflags &= ~TF_MASK;
|
|
|
|
|
if (next_eip) {
|
|
|
|
|
regs->eip = next_eip;
|
|
|
|
|
} else {
|
|
|
|
|
regs->eip = orig_eip + (regs->eip - copy_eip);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
|
2005-11-07 09:00:14 +00:00
|
|
|
* remain disabled thoroughout this function.
|
2005-04-16 22:20:36 +00:00
|
|
|
*/
|
|
|
|
|
static inline int post_kprobe_handler(struct pt_regs *regs)
|
|
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
struct kprobe *cur = kprobe_running();
|
|
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
|
|
|
|
|
|
if (!cur)
|
2005-04-16 22:20:36 +00:00
|
|
|
return 0;
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
|
|
|
|
|
kcb->kprobe_status = KPROBE_HIT_SSDONE;
|
|
|
|
|
cur->post_handler(cur, regs, 0);
|
2005-06-23 07:09:37 +00:00
|
|
|
}
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
resume_execution(cur, regs, kcb);
|
|
|
|
|
regs->eflags |= kcb->kprobe_saved_eflags;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2005-06-23 07:09:37 +00:00
|
|
|
/*Restore back the original saved kprobes variables and continue. */
|
2005-11-07 09:00:08 +00:00
|
|
|
if (kcb->kprobe_status == KPROBE_REENTER) {
|
|
|
|
|
restore_previous_kprobe(kcb);
|
2005-06-23 07:09:37 +00:00
|
|
|
goto out;
|
|
|
|
|
}
|
2005-11-07 09:00:08 +00:00
|
|
|
reset_current_kprobe();
|
2005-06-23 07:09:37 +00:00
|
|
|
out:
|
2005-04-16 22:20:36 +00:00
|
|
|
preempt_enable_no_resched();
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* if somebody else is singlestepping across a probe point, eflags
|
|
|
|
|
* will have TF set, in which case, continue the remaining processing
|
|
|
|
|
* of do_debug, as if this is not a probe hit.
|
|
|
|
|
*/
|
|
|
|
|
if (regs->eflags & TF_MASK)
|
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
|
|
return 1;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
|
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
struct kprobe *cur = kprobe_running();
|
|
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
|
|
|
|
|
|
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
|
2005-04-16 22:20:36 +00:00
|
|
|
return 1;
|
|
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
if (kcb->kprobe_status & KPROBE_HIT_SS) {
|
|
|
|
|
resume_execution(cur, regs, kcb);
|
|
|
|
|
regs->eflags |= kcb->kprobe_old_eflags;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
reset_current_kprobe();
|
2005-04-16 22:20:36 +00:00
|
|
|
preempt_enable_no_resched();
|
|
|
|
|
}
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Wrapper routine to for handling exceptions.
|
|
|
|
|
*/
|
2005-09-06 22:19:27 +00:00
|
|
|
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
|
|
|
|
|
unsigned long val, void *data)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
struct die_args *args = (struct die_args *)data;
|
2005-11-07 09:00:07 +00:00
|
|
|
int ret = NOTIFY_DONE;
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
switch (val) {
|
|
|
|
|
case DIE_INT3:
|
|
|
|
|
if (kprobe_handler(args->regs))
|
2005-11-07 09:00:07 +00:00
|
|
|
ret = NOTIFY_STOP;
|
2005-04-16 22:20:36 +00:00
|
|
|
break;
|
|
|
|
|
case DIE_DEBUG:
|
|
|
|
|
if (post_kprobe_handler(args->regs))
|
2005-11-07 09:00:07 +00:00
|
|
|
ret = NOTIFY_STOP;
|
2005-04-16 22:20:36 +00:00
|
|
|
break;
|
|
|
|
|
case DIE_GPF:
|
|
|
|
|
case DIE_PAGE_FAULT:
|
2005-11-07 09:00:14 +00:00
|
|
|
/* kprobe_running() needs smp_processor_id() */
|
|
|
|
|
preempt_disable();
|
2005-04-16 22:20:36 +00:00
|
|
|
if (kprobe_running() &&
|
|
|
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
2005-11-07 09:00:07 +00:00
|
|
|
ret = NOTIFY_STOP;
|
2005-11-07 09:00:14 +00:00
|
|
|
preempt_enable();
|
2005-04-16 22:20:36 +00:00
|
|
|
break;
|
|
|
|
|
default:
|
|
|
|
|
break;
|
|
|
|
|
}
|
2005-11-07 09:00:07 +00:00
|
|
|
return ret;
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
|
|
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
|
|
|
unsigned long addr;
|
2005-11-07 09:00:08 +00:00
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2005-11-07 09:00:08 +00:00
|
|
|
kcb->jprobe_saved_regs = *regs;
|
|
|
|
|
kcb->jprobe_saved_esp = ®s->esp;
|
|
|
|
|
addr = (unsigned long)(kcb->jprobe_saved_esp);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* TBD: As Linus pointed out, gcc assumes that the callee
|
|
|
|
|
* owns the argument space and could overwrite it, e.g.
|
|
|
|
|
* tailcall optimization. So, to be absolutely safe
|
|
|
|
|
* we also save and restore enough stack bytes to cover
|
|
|
|
|
* the argument area.
|
|
|
|
|
*/
|
2005-11-07 09:00:08 +00:00
|
|
|
memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
|
|
|
|
|
MIN_STACK_SIZE(addr));
|
2005-04-16 22:20:36 +00:00
|
|
|
regs->eflags &= ~IF_MASK;
|
|
|
|
|
regs->eip = (unsigned long)(jp->entry);
|
|
|
|
|
return 1;
|
|
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
void __kprobes jprobe_return(void)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
asm volatile (" xchgl %%ebx,%%esp \n"
|
|
|
|
|
" int3 \n"
|
|
|
|
|
" .globl jprobe_return_end \n"
|
|
|
|
|
" jprobe_return_end: \n"
|
|
|
|
|
" nop \n"::"b"
|
2005-11-07 09:00:08 +00:00
|
|
|
(kcb->jprobe_saved_esp):"memory");
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
2005-09-06 22:19:27 +00:00
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
2005-04-16 22:20:36 +00:00
|
|
|
{
|
2005-11-07 09:00:08 +00:00
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
2005-04-16 22:20:36 +00:00
|
|
|
u8 *addr = (u8 *) (regs->eip - 1);
|
2005-11-07 09:00:08 +00:00
|
|
|
unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
|
2005-04-16 22:20:36 +00:00
|
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
|
|
|
|
|
|
|
|
if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
|
2005-11-07 09:00:08 +00:00
|
|
|
if (®s->esp != kcb->jprobe_saved_esp) {
|
2005-04-16 22:20:36 +00:00
|
|
|
struct pt_regs *saved_regs =
|
2005-11-07 09:00:08 +00:00
|
|
|
container_of(kcb->jprobe_saved_esp,
|
|
|
|
|
struct pt_regs, esp);
|
2005-04-16 22:20:36 +00:00
|
|
|
printk("current esp %p does not match saved esp %p\n",
|
2005-11-07 09:00:08 +00:00
|
|
|
®s->esp, kcb->jprobe_saved_esp);
|
2005-04-16 22:20:36 +00:00
|
|
|
printk("Saved registers for jprobe %p\n", jp);
|
|
|
|
|
show_registers(saved_regs);
|
|
|
|
|
printk("Current registers\n");
|
|
|
|
|
show_registers(regs);
|
|
|
|
|
BUG();
|
|
|
|
|
}
|
2005-11-07 09:00:08 +00:00
|
|
|
*regs = kcb->jprobe_saved_regs;
|
|
|
|
|
memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
|
2005-04-16 22:20:36 +00:00
|
|
|
MIN_STACK_SIZE(stack_addr));
|
2005-11-07 09:00:14 +00:00
|
|
|
preempt_enable_no_resched();
|
2005-04-16 22:20:36 +00:00
|
|
|
return 1;
|
|
|
|
|
}
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
2005-06-27 22:17:09 +00:00
|
|
|
|
|
|
|
|
static struct kprobe trampoline_p = {
|
|
|
|
|
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
|
|
|
|
|
.pre_handler = trampoline_probe_handler
|
|
|
|
|
};
|
|
|
|
|
|
2005-07-06 01:54:50 +00:00
|
|
|
int __init arch_init_kprobes(void)
|
2005-06-27 22:17:09 +00:00
|
|
|
{
|
|
|
|
|
return register_kprobe(&trampoline_p);
|
|
|
|
|
}
|
