mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
2d8ab6ad6e
The incorrect kprobe_mutex usage on x86_64 had percolated to ppc64 too. First noticed by Yanmin Zhang. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
453 lines
12 KiB
C
453 lines
12 KiB
C
/*
|
|
* Kernel Probes (KProbes)
|
|
* arch/ppc64/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.
|
|
* 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
|
|
* for PPC64
|
|
*/
|
|
|
|
#include <linux/config.h>
|
|
#include <linux/kprobes.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/preempt.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/kdebug.h>
|
|
#include <asm/sstep.h>
|
|
|
|
static DECLARE_MUTEX(kprobe_mutex);
|
|
|
|
static struct kprobe *current_kprobe;
|
|
static unsigned long kprobe_status, kprobe_saved_msr;
|
|
static struct kprobe *kprobe_prev;
|
|
static unsigned long kprobe_status_prev, kprobe_saved_msr_prev;
|
|
static struct pt_regs jprobe_saved_regs;
|
|
|
|
int __kprobes arch_prepare_kprobe(struct kprobe *p)
|
|
{
|
|
int ret = 0;
|
|
kprobe_opcode_t insn = *p->addr;
|
|
|
|
if ((unsigned long)p->addr & 0x03) {
|
|
printk("Attempt to register kprobe at an unaligned address\n");
|
|
ret = -EINVAL;
|
|
} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
|
|
printk("Cannot register a kprobe on rfid or mtmsrd\n");
|
|
ret = -EINVAL;
|
|
}
|
|
|
|
/* insn must be on a special executable page on ppc64 */
|
|
if (!ret) {
|
|
down(&kprobe_mutex);
|
|
p->ainsn.insn = get_insn_slot();
|
|
up(&kprobe_mutex);
|
|
if (!p->ainsn.insn)
|
|
ret = -ENOMEM;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
void __kprobes arch_copy_kprobe(struct kprobe *p)
|
|
{
|
|
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
|
|
p->opcode = *p->addr;
|
|
}
|
|
|
|
void __kprobes arch_arm_kprobe(struct kprobe *p)
|
|
{
|
|
*p->addr = BREAKPOINT_INSTRUCTION;
|
|
flush_icache_range((unsigned long) p->addr,
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
|
}
|
|
|
|
void __kprobes arch_disarm_kprobe(struct kprobe *p)
|
|
{
|
|
*p->addr = p->opcode;
|
|
flush_icache_range((unsigned long) p->addr,
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
|
}
|
|
|
|
void __kprobes arch_remove_kprobe(struct kprobe *p)
|
|
{
|
|
down(&kprobe_mutex);
|
|
free_insn_slot(p->ainsn.insn);
|
|
up(&kprobe_mutex);
|
|
}
|
|
|
|
static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
kprobe_opcode_t insn = *p->ainsn.insn;
|
|
|
|
regs->msr |= MSR_SE;
|
|
|
|
/* single step inline if it is a trap variant */
|
|
if (is_trap(insn))
|
|
regs->nip = (unsigned long)p->addr;
|
|
else
|
|
regs->nip = (unsigned long)p->ainsn.insn;
|
|
}
|
|
|
|
static inline void save_previous_kprobe(void)
|
|
{
|
|
kprobe_prev = current_kprobe;
|
|
kprobe_status_prev = kprobe_status;
|
|
kprobe_saved_msr_prev = kprobe_saved_msr;
|
|
}
|
|
|
|
static inline void restore_previous_kprobe(void)
|
|
{
|
|
current_kprobe = kprobe_prev;
|
|
kprobe_status = kprobe_status_prev;
|
|
kprobe_saved_msr = kprobe_saved_msr_prev;
|
|
}
|
|
|
|
void __kprobes 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->link;
|
|
|
|
/* Replace the return addr with trampoline addr */
|
|
regs->link = (unsigned long)kretprobe_trampoline;
|
|
add_rp_inst(ri);
|
|
} else {
|
|
rp->nmissed++;
|
|
}
|
|
}
|
|
|
|
static inline int kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kprobe *p;
|
|
int ret = 0;
|
|
unsigned int *addr = (unsigned int *)regs->nip;
|
|
|
|
/* Check we're not actually recursing */
|
|
if (kprobe_running()) {
|
|
/* We *are* holding lock here, so this is safe.
|
|
Disarm the probe we just hit, and ignore it. */
|
|
p = get_kprobe(addr);
|
|
if (p) {
|
|
kprobe_opcode_t insn = *p->ainsn.insn;
|
|
if (kprobe_status == KPROBE_HIT_SS &&
|
|
is_trap(insn)) {
|
|
regs->msr &= ~MSR_SE;
|
|
regs->msr |= kprobe_saved_msr;
|
|
unlock_kprobes();
|
|
goto no_kprobe;
|
|
}
|
|
/* 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.
|
|
*/
|
|
save_previous_kprobe();
|
|
current_kprobe = p;
|
|
kprobe_saved_msr = regs->msr;
|
|
p->nmissed++;
|
|
prepare_singlestep(p, regs);
|
|
kprobe_status = KPROBE_REENTER;
|
|
return 1;
|
|
} else {
|
|
p = current_kprobe;
|
|
if (p->break_handler && p->break_handler(p, regs)) {
|
|
goto ss_probe;
|
|
}
|
|
}
|
|
/* If it's not ours, can't be delete race, (we hold lock). */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
lock_kprobes();
|
|
p = get_kprobe(addr);
|
|
if (!p) {
|
|
unlock_kprobes();
|
|
if (*addr != BREAKPOINT_INSTRUCTION) {
|
|
/*
|
|
* PowerPC has multiple variants of the "trap"
|
|
* instruction. If the current instruction is a
|
|
* trap variant, it could belong to someone else
|
|
*/
|
|
kprobe_opcode_t cur_insn = *addr;
|
|
if (is_trap(cur_insn))
|
|
goto no_kprobe;
|
|
/*
|
|
* The breakpoint instruction was removed right
|
|
* after we hit it. Another cpu has removed
|
|
* either a probepoint or a debugger breakpoint
|
|
* at this address. In either case, no further
|
|
* handling of this interrupt is appropriate.
|
|
*/
|
|
ret = 1;
|
|
}
|
|
/* Not one of ours: let kernel handle it */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
kprobe_status = KPROBE_HIT_ACTIVE;
|
|
current_kprobe = p;
|
|
kprobe_saved_msr = regs->msr;
|
|
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);
|
|
kprobe_status = KPROBE_HIT_SS;
|
|
/*
|
|
* This preempt_disable() matches the preempt_enable_no_resched()
|
|
* in post_kprobe_handler().
|
|
*/
|
|
preempt_disable();
|
|
return 1;
|
|
|
|
no_kprobe:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Function return probe trampoline:
|
|
* - init_kprobes() establishes a probepoint here
|
|
* - When the probed function returns, this probe
|
|
* causes the handlers to fire
|
|
*/
|
|
void kretprobe_trampoline_holder(void)
|
|
{
|
|
asm volatile(".global kretprobe_trampoline\n"
|
|
"kretprobe_trampoline:\n"
|
|
"nop\n");
|
|
}
|
|
|
|
/*
|
|
* Called when the probe at kretprobe trampoline is hit
|
|
*/
|
|
int __kprobes 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 =(unsigned long)&kretprobe_trampoline;
|
|
|
|
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->nip = orig_ret_address;
|
|
|
|
unlock_kprobes();
|
|
|
|
/*
|
|
* By returning a non-zero value, we are telling
|
|
* kprobe_handler() that we have handled unlocking
|
|
* and re-enabling preemption.
|
|
*/
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Called after single-stepping. p->addr is the address of the
|
|
* instruction whose first byte has been replaced by the "breakpoint"
|
|
* 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.
|
|
*/
|
|
static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
int ret;
|
|
unsigned int insn = *p->ainsn.insn;
|
|
|
|
regs->nip = (unsigned long)p->addr;
|
|
ret = emulate_step(regs, insn);
|
|
if (ret == 0)
|
|
regs->nip = (unsigned long)p->addr + 4;
|
|
}
|
|
|
|
static inline int post_kprobe_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);
|
|
regs->msr |= kprobe_saved_msr;
|
|
|
|
/*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();
|
|
|
|
/*
|
|
* if somebody else is singlestepping across a probe point, msr
|
|
* will have SE set, in which case, continue the remaining processing
|
|
* of do_debug, as if this is not a probe hit.
|
|
*/
|
|
if (regs->msr & MSR_SE)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Interrupts disabled, kprobe_lock held. */
|
|
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
|
{
|
|
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);
|
|
regs->msr &= ~MSR_SE;
|
|
regs->msr |= kprobe_saved_msr;
|
|
|
|
unlock_kprobes();
|
|
preempt_enable_no_resched();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Wrapper routine to for handling exceptions.
|
|
*/
|
|
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
|
|
unsigned long val, void *data)
|
|
{
|
|
struct die_args *args = (struct die_args *)data;
|
|
int ret = NOTIFY_DONE;
|
|
|
|
/*
|
|
* Interrupts are not disabled here. We need to disable
|
|
* preemption, because kprobe_running() uses smp_processor_id().
|
|
*/
|
|
preempt_disable();
|
|
switch (val) {
|
|
case DIE_BPT:
|
|
if (kprobe_handler(args->regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_SSTEP:
|
|
if (post_kprobe_handler(args->regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_GPF:
|
|
case DIE_PAGE_FAULT:
|
|
if (kprobe_running() &&
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
preempt_enable_no_resched();
|
|
return ret;
|
|
}
|
|
|
|
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
|
|
memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
|
|
|
|
/* setup return addr to the jprobe handler routine */
|
|
regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
|
|
regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
|
|
|
|
return 1;
|
|
}
|
|
|
|
void __kprobes jprobe_return(void)
|
|
{
|
|
asm volatile("trap" ::: "memory");
|
|
}
|
|
|
|
void __kprobes jprobe_return_end(void)
|
|
{
|
|
};
|
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
/*
|
|
* FIXME - we should ideally be validating that we got here 'cos
|
|
* of the "trap" in jprobe_return() above, before restoring the
|
|
* saved regs...
|
|
*/
|
|
memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
|
|
return 1;
|
|
}
|
|
|
|
static struct kprobe trampoline_p = {
|
|
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
|
|
.pre_handler = trampoline_probe_handler
|
|
};
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
return register_kprobe(&trampoline_p);
|
|
}
|