linux/arch/arm/kernel/kprobes.c
Sasha Levin b67bfe0d42 hlist: drop the node parameter from iterators
I'm not sure why, but the hlist for each entry iterators were conceived

        list_for_each_entry(pos, head, member)

The hlist ones were greedy and wanted an extra parameter:

        hlist_for_each_entry(tpos, pos, head, member)

Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.

Besides the semantic patch, there was some manual work required:

 - Fix up the actual hlist iterators in linux/list.h
 - Fix up the declaration of other iterators based on the hlist ones.
 - A very small amount of places were using the 'node' parameter, this
 was modified to use 'obj->member' instead.
 - Coccinelle didn't handle the hlist_for_each_entry_safe iterator
 properly, so those had to be fixed up manually.

The semantic patch which is mostly the work of Peter Senna Tschudin is here:

@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;

type T;
expression a,c,d,e;
identifier b;
statement S;
@@

-T b;
    <+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
    ...+>

[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-02-27 19:10:24 -08:00

619 lines
16 KiB
C

/*
* arch/arm/kernel/kprobes.c
*
* Kprobes on ARM
*
* Abhishek Sagar <sagar.abhishek@gmail.com>
* Copyright (C) 2006, 2007 Motorola Inc.
*
* Nicolas Pitre <nico@marvell.com>
* Copyright (C) 2007 Marvell Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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.
*/
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/stop_machine.h>
#include <linux/stringify.h>
#include <asm/traps.h>
#include <asm/cacheflush.h>
#include "kprobes.h"
#include "patch.h"
#define MIN_STACK_SIZE(addr) \
min((unsigned long)MAX_STACK_SIZE, \
(unsigned long)current_thread_info() + THREAD_START_SP - (addr))
#define flush_insns(addr, size) \
flush_icache_range((unsigned long)(addr), \
(unsigned long)(addr) + \
(size))
/* Used as a marker in ARM_pc to note when we're in a jprobe. */
#define JPROBE_MAGIC_ADDR 0xffffffff
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
kprobe_opcode_t insn;
kprobe_opcode_t tmp_insn[MAX_INSN_SIZE];
unsigned long addr = (unsigned long)p->addr;
bool thumb;
kprobe_decode_insn_t *decode_insn;
int is;
if (in_exception_text(addr))
return -EINVAL;
#ifdef CONFIG_THUMB2_KERNEL
thumb = true;
addr &= ~1; /* Bit 0 would normally be set to indicate Thumb code */
insn = ((u16 *)addr)[0];
if (is_wide_instruction(insn)) {
insn <<= 16;
insn |= ((u16 *)addr)[1];
decode_insn = thumb32_kprobe_decode_insn;
} else
decode_insn = thumb16_kprobe_decode_insn;
#else /* !CONFIG_THUMB2_KERNEL */
thumb = false;
if (addr & 0x3)
return -EINVAL;
insn = *p->addr;
decode_insn = arm_kprobe_decode_insn;
#endif
p->opcode = insn;
p->ainsn.insn = tmp_insn;
switch ((*decode_insn)(insn, &p->ainsn)) {
case INSN_REJECTED: /* not supported */
return -EINVAL;
case INSN_GOOD: /* instruction uses slot */
p->ainsn.insn = get_insn_slot();
if (!p->ainsn.insn)
return -ENOMEM;
for (is = 0; is < MAX_INSN_SIZE; ++is)
p->ainsn.insn[is] = tmp_insn[is];
flush_insns(p->ainsn.insn,
sizeof(p->ainsn.insn[0]) * MAX_INSN_SIZE);
p->ainsn.insn_fn = (kprobe_insn_fn_t *)
((uintptr_t)p->ainsn.insn | thumb);
break;
case INSN_GOOD_NO_SLOT: /* instruction doesn't need insn slot */
p->ainsn.insn = NULL;
break;
}
return 0;
}
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
unsigned int brkp;
void *addr;
if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
/* Remove any Thumb flag */
addr = (void *)((uintptr_t)p->addr & ~1);
if (is_wide_instruction(p->opcode))
brkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION;
else
brkp = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION;
} else {
kprobe_opcode_t insn = p->opcode;
addr = p->addr;
brkp = KPROBE_ARM_BREAKPOINT_INSTRUCTION;
if (insn >= 0xe0000000)
brkp |= 0xe0000000; /* Unconditional instruction */
else
brkp |= insn & 0xf0000000; /* Copy condition from insn */
}
patch_text(addr, brkp);
}
/*
* The actual disarming is done here on each CPU and synchronized using
* stop_machine. This synchronization is necessary on SMP to avoid removing
* a probe between the moment the 'Undefined Instruction' exception is raised
* and the moment the exception handler reads the faulting instruction from
* memory. It is also needed to atomically set the two half-words of a 32-bit
* Thumb breakpoint.
*/
int __kprobes __arch_disarm_kprobe(void *p)
{
struct kprobe *kp = p;
void *addr = (void *)((uintptr_t)kp->addr & ~1);
__patch_text(addr, kp->opcode);
return 0;
}
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
stop_machine(__arch_disarm_kprobe, p, cpu_online_mask);
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
if (p->ainsn.insn) {
free_insn_slot(p->ainsn.insn, 0);
p->ainsn.insn = NULL;
}
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
}
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
}
static void __kprobes set_current_kprobe(struct kprobe *p)
{
__get_cpu_var(current_kprobe) = p;
}
static void __kprobes
singlestep_skip(struct kprobe *p, struct pt_regs *regs)
{
#ifdef CONFIG_THUMB2_KERNEL
regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
if (is_wide_instruction(p->opcode))
regs->ARM_pc += 4;
else
regs->ARM_pc += 2;
#else
regs->ARM_pc += 4;
#endif
}
static inline void __kprobes
singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
{
p->ainsn.insn_singlestep(p, regs);
}
/*
* Called with IRQs disabled. IRQs must remain disabled from that point
* all the way until processing this kprobe is complete. The current
* kprobes implementation cannot process more than one nested level of
* kprobe, and that level is reserved for user kprobe handlers, so we can't
* risk encountering a new kprobe in an interrupt handler.
*/
void __kprobes kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p, *cur;
struct kprobe_ctlblk *kcb;
kcb = get_kprobe_ctlblk();
cur = kprobe_running();
#ifdef CONFIG_THUMB2_KERNEL
/*
* First look for a probe which was registered using an address with
* bit 0 set, this is the usual situation for pointers to Thumb code.
* If not found, fallback to looking for one with bit 0 clear.
*/
p = get_kprobe((kprobe_opcode_t *)(regs->ARM_pc | 1));
if (!p)
p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc);
#else /* ! CONFIG_THUMB2_KERNEL */
p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc);
#endif
if (p) {
if (cur) {
/* Kprobe is pending, so we're recursing. */
switch (kcb->kprobe_status) {
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
/* A pre- or post-handler probe got us here. */
kprobes_inc_nmissed_count(p);
save_previous_kprobe(kcb);
set_current_kprobe(p);
kcb->kprobe_status = KPROBE_REENTER;
singlestep(p, regs, kcb);
restore_previous_kprobe(kcb);
break;
default:
/* impossible cases */
BUG();
}
} else if (p->ainsn.insn_check_cc(regs->ARM_cpsr)) {
/* Probe hit and conditional execution check ok. */
set_current_kprobe(p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
/*
* If we have no pre-handler or it returned 0, we
* continue with normal processing. If we have a
* pre-handler and it returned non-zero, it prepped
* for calling the break_handler below on re-entry,
* so get out doing nothing more here.
*/
if (!p->pre_handler || !p->pre_handler(p, regs)) {
kcb->kprobe_status = KPROBE_HIT_SS;
singlestep(p, regs, kcb);
if (p->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
p->post_handler(p, regs, 0);
}
reset_current_kprobe();
}
} else {
/*
* Probe hit but conditional execution check failed,
* so just skip the instruction and continue as if
* nothing had happened.
*/
singlestep_skip(p, regs);
}
} else if (cur) {
/* We probably hit a jprobe. Call its break handler. */
if (cur->break_handler && cur->break_handler(cur, regs)) {
kcb->kprobe_status = KPROBE_HIT_SS;
singlestep(cur, regs, kcb);
if (cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
}
}
reset_current_kprobe();
} else {
/*
* The probe was removed and a race is in progress.
* There is nothing we can do about it. Let's restart
* the instruction. By the time we can restart, the
* real instruction will be there.
*/
}
}
static int __kprobes kprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
{
unsigned long flags;
local_irq_save(flags);
kprobe_handler(regs);
local_irq_restore(flags);
return 0;
}
int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
switch (kcb->kprobe_status) {
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe and the PC to point back to the probe address
* and allow the page fault handler to continue as a
* normal page fault.
*/
regs->ARM_pc = (long)cur->addr;
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
} else {
reset_current_kprobe();
}
break;
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
/*
* We increment the nmissed count for accounting,
* we can also use npre/npostfault count for accounting
* these specific fault cases.
*/
kprobes_inc_nmissed_count(cur);
/*
* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it.
*/
if (cur->fault_handler && cur->fault_handler(cur, regs, fsr))
return 1;
break;
default:
break;
}
return 0;
}
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
/*
* notify_die() is currently never called on ARM,
* so this callback is currently empty.
*/
return NOTIFY_DONE;
}
/*
* When a retprobed function returns, trampoline_handler() is called,
* calling the kretprobe's handler. We construct a struct pt_regs to
* give a view of registers r0-r11 to the user return-handler. This is
* not a complete pt_regs structure, but that should be plenty sufficient
* for kretprobe handlers which should normally be interested in r0 only
* anyway.
*/
void __naked __kprobes kretprobe_trampoline(void)
{
__asm__ __volatile__ (
"stmdb sp!, {r0 - r11} \n\t"
"mov r0, sp \n\t"
"bl trampoline_handler \n\t"
"mov lr, r0 \n\t"
"ldmia sp!, {r0 - r11} \n\t"
#ifdef CONFIG_THUMB2_KERNEL
"bx lr \n\t"
#else
"mov pc, lr \n\t"
#endif
: : : "memory");
}
/* Called from kretprobe_trampoline */
static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
{
struct kretprobe_instance *ri = NULL;
struct hlist_head *head, empty_rp;
struct hlist_node *tmp;
unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags);
/*
* It is possible to have multiple instances associated with a given
* task either because multiple functions in the call path have
* a return probe installed on them, and/or more than one 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, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
if (ri->rp && ri->rp->handler) {
__get_cpu_var(current_kprobe) = &ri->rp->kp;
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
ri->rp->handler(ri, regs);
__get_cpu_var(current_kprobe) = NULL;
}
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri, &empty_rp);
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;
}
kretprobe_assert(ri, orig_ret_address, trampoline_address);
kretprobe_hash_unlock(current, &flags);
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
return (void *)orig_ret_address;
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->ARM_lr;
/* Replace the return addr with trampoline addr. */
regs->ARM_lr = (unsigned long)&kretprobe_trampoline;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
long sp_addr = regs->ARM_sp;
long cpsr;
kcb->jprobe_saved_regs = *regs;
memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr));
regs->ARM_pc = (long)jp->entry;
cpsr = regs->ARM_cpsr | PSR_I_BIT;
#ifdef CONFIG_THUMB2_KERNEL
/* Set correct Thumb state in cpsr */
if (regs->ARM_pc & 1)
cpsr |= PSR_T_BIT;
else
cpsr &= ~PSR_T_BIT;
#endif
regs->ARM_cpsr = cpsr;
preempt_disable();
return 1;
}
void __kprobes jprobe_return(void)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
__asm__ __volatile__ (
/*
* Setup an empty pt_regs. Fill SP and PC fields as
* they're needed by longjmp_break_handler.
*
* We allocate some slack between the original SP and start of
* our fabricated regs. To be precise we want to have worst case
* covered which is STMFD with all 16 regs so we allocate 2 *
* sizeof(struct_pt_regs)).
*
* This is to prevent any simulated instruction from writing
* over the regs when they are accessing the stack.
*/
#ifdef CONFIG_THUMB2_KERNEL
"sub r0, %0, %1 \n\t"
"mov sp, r0 \n\t"
#else
"sub sp, %0, %1 \n\t"
#endif
"ldr r0, ="__stringify(JPROBE_MAGIC_ADDR)"\n\t"
"str %0, [sp, %2] \n\t"
"str r0, [sp, %3] \n\t"
"mov r0, sp \n\t"
"bl kprobe_handler \n\t"
/*
* Return to the context saved by setjmp_pre_handler
* and restored by longjmp_break_handler.
*/
#ifdef CONFIG_THUMB2_KERNEL
"ldr lr, [sp, %2] \n\t" /* lr = saved sp */
"ldrd r0, r1, [sp, %5] \n\t" /* r0,r1 = saved lr,pc */
"ldr r2, [sp, %4] \n\t" /* r2 = saved psr */
"stmdb lr!, {r0, r1, r2} \n\t" /* push saved lr and */
/* rfe context */
"ldmia sp, {r0 - r12} \n\t"
"mov sp, lr \n\t"
"ldr lr, [sp], #4 \n\t"
"rfeia sp! \n\t"
#else
"ldr r0, [sp, %4] \n\t"
"msr cpsr_cxsf, r0 \n\t"
"ldmia sp, {r0 - pc} \n\t"
#endif
:
: "r" (kcb->jprobe_saved_regs.ARM_sp),
"I" (sizeof(struct pt_regs) * 2),
"J" (offsetof(struct pt_regs, ARM_sp)),
"J" (offsetof(struct pt_regs, ARM_pc)),
"J" (offsetof(struct pt_regs, ARM_cpsr)),
"J" (offsetof(struct pt_regs, ARM_lr))
: "memory", "cc");
}
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
long stack_addr = kcb->jprobe_saved_regs.ARM_sp;
long orig_sp = regs->ARM_sp;
struct jprobe *jp = container_of(p, struct jprobe, kp);
if (regs->ARM_pc == JPROBE_MAGIC_ADDR) {
if (orig_sp != stack_addr) {
struct pt_regs *saved_regs =
(struct pt_regs *)kcb->jprobe_saved_regs.ARM_sp;
printk("current sp %lx does not match saved sp %lx\n",
orig_sp, stack_addr);
printk("Saved registers for jprobe %p\n", jp);
show_regs(saved_regs);
printk("Current registers\n");
show_regs(regs);
BUG();
}
*regs = kcb->jprobe_saved_regs;
memcpy((void *)stack_addr, kcb->jprobes_stack,
MIN_STACK_SIZE(stack_addr));
preempt_enable_no_resched();
return 1;
}
return 0;
}
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
return 0;
}
#ifdef CONFIG_THUMB2_KERNEL
static struct undef_hook kprobes_thumb16_break_hook = {
.instr_mask = 0xffff,
.instr_val = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION,
.cpsr_mask = MODE_MASK,
.cpsr_val = SVC_MODE,
.fn = kprobe_trap_handler,
};
static struct undef_hook kprobes_thumb32_break_hook = {
.instr_mask = 0xffffffff,
.instr_val = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION,
.cpsr_mask = MODE_MASK,
.cpsr_val = SVC_MODE,
.fn = kprobe_trap_handler,
};
#else /* !CONFIG_THUMB2_KERNEL */
static struct undef_hook kprobes_arm_break_hook = {
.instr_mask = 0x0fffffff,
.instr_val = KPROBE_ARM_BREAKPOINT_INSTRUCTION,
.cpsr_mask = MODE_MASK,
.cpsr_val = SVC_MODE,
.fn = kprobe_trap_handler,
};
#endif /* !CONFIG_THUMB2_KERNEL */
int __init arch_init_kprobes()
{
arm_kprobe_decode_init();
#ifdef CONFIG_THUMB2_KERNEL
register_undef_hook(&kprobes_thumb16_break_hook);
register_undef_hook(&kprobes_thumb32_break_hook);
#else
register_undef_hook(&kprobes_arm_break_hook);
#endif
return 0;
}