#include <linux/ptrace.h>
#include <linux/spinlock.h>
#include <linux/preempt.h>
+#include <asm/cacheflush.h>
#include <asm/kdebug.h>
#include <asm/sstep.h>
-/* kprobe_status settings */
-#define KPROBE_HIT_ACTIVE 0x00000001
-#define KPROBE_HIT_SS 0x00000002
+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 arch_prepare_kprobe(struct kprobe *p)
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
int ret = 0;
kprobe_opcode_t insn = *p->addr;
printk("Cannot register a kprobe on rfid or mtmsrd\n");
ret = -EINVAL;
}
+
+ /* insn must be on a special executable page on ppc64 */
+ if (!ret) {
+ up(&kprobe_mutex);
+ p->ainsn.insn = get_insn_slot();
+ down(&kprobe_mutex);
+ if (!p->ainsn.insn)
+ ret = -ENOMEM;
+ }
return ret;
}
-void arch_copy_kprobe(struct kprobe *p)
+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 arch_remove_kprobe(struct kprobe *p)
+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));
}
-static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs)
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
*p->addr = p->opcode;
- regs->nip = (unsigned long)p->addr;
+ flush_icache_range((unsigned long) p->addr,
+ (unsigned long) p->addr + sizeof(kprobe_opcode_t));
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ up(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn);
+ down(&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 a breakpoint instruction*/
- if (p->opcode == BREAKPOINT_INSTRUCTION)
+
+ /* 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;
+ 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)
Disarm the probe we just hit, and ignore it. */
p = get_kprobe(addr);
if (p) {
- if (kprobe_status == KPROBE_HIT_SS) {
+ 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;
}
- disarm_kprobe(p, regs);
- ret = 1;
+ /* 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)) {
* trap variant, it could belong to someone else
*/
kprobe_opcode_t cur_insn = *addr;
- if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
- IS_TWI(cur_insn) || IS_TDI(cur_insn))
+ if (is_trap(cur_insn))
goto no_kprobe;
/*
* The breakpoint instruction was removed right
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"
* single-stepped a copy of the instruction. The address of this
* copy is p->ainsn.insn.
*/
-static void resume_execution(struct kprobe *p, struct pt_regs *regs)
+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, p->ainsn.insn[0]);
+ ret = emulate_step(regs, insn);
if (ret == 0)
regs->nip = (unsigned long)p->addr + 4;
}
if (!kprobe_running())
return 0;
- if (current_kprobe->post_handler)
+ 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();
/*
/*
* Wrapper routine to for handling exceptions.
*/
-int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
- void *data)
+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;
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))
default:
break;
}
- preempt_enable();
+ preempt_enable_no_resched();
return ret;
}
-int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
return 1;
}
-void jprobe_return(void)
+void __kprobes jprobe_return(void)
{
asm volatile("trap" ::: "memory");
}
-void jprobe_return_end(void)
+void __kprobes jprobe_return_end(void)
{
};
-int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
/*
* FIXME - we should ideally be validating that we got here 'cos
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);
+}
projects / karo-tx-linux.git / blobdiff