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parisc: Implement kretprobes 

Implement kretprobes on parisc, parts stolen from powerpc.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Sven Schnelle 2019-04-09 19:30:28 +02:00 committed by Helge Deller
parent 1253d18d2d
commit e0b59b7b63
2 changed files with 110 additions and 1 deletions
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1
arch/parisc/Kconfig
View File

@ -56,6 +56,7 @@ config PARISC
select NEED_SG_DMA_LENGTH
select HAVE_ARCH_KGDB
select HAVE_KPROBES
select HAVE_KRETPROBES
help
The PA-RISC microprocessor is designed by Hewlett-Packard and used

110
arch/parisc/kernel/kprobes.c
View File

@ -172,6 +172,112 @@ int __kprobes parisc_kprobe_ss_handler(struct pt_regs *regs)
return 1;
}
static inline void kretprobe_trampoline(void)
{
asm volatile("nop");
asm volatile("nop");
}
static int __kprobes trampoline_probe_handler(struct kprobe *p,
struct pt_regs *regs);
static struct kprobe trampoline_p = {
.pre_handler = trampoline_probe_handler
};
static int __kprobes trampoline_probe_handler(struct kprobe *p,
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)trampoline_p.addr;
kprobe_opcode_t *correct_ret_addr = NULL;
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;
orig_ret_address = (unsigned long)ri->ret_addr;
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);
correct_ret_addr = ri->ret_addr;
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
orig_ret_address = (unsigned long)ri->ret_addr;
if (ri->rp && ri->rp->handler) {
__this_cpu_write(current_kprobe, &ri->rp->kp);
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
ri->ret_addr = correct_ret_addr;
ri->rp->handler(ri, regs);
__this_cpu_write(current_kprobe, NULL);
}
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_hash_unlock(current, &flags);
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
instruction_pointer_set(regs, orig_ret_address);
return 1;
}
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *)regs->gr[2];
/* Replace the return addr with trampoline addr. */
regs->gr[2] = (unsigned long)trampoline_p.addr;
}
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
return p->addr == trampoline_p.addr;
}
bool arch_kprobe_on_func_entry(unsigned long offset)
{
return !offset;
@ -179,5 +285,7 @@ bool arch_kprobe_on_func_entry(unsigned long offset)
int __init arch_init_kprobes(void)
{
return 0;
trampoline_p.addr = (kprobe_opcode_t *)
dereference_function_descriptor(kretprobe_trampoline);
return register_kprobe(&trampoline_p);
}