Implement kretprobes on parisc, parts stolen from powerpc.
Signed-off-by: Sven Schnelle <svens@xxxxxxxxxxxxxx>
---
arch/parisc/Kconfig | 1 +
arch/parisc/kernel/kprobes.c | 110 ++++++++++++++++++++++++++++++++++-
2 files changed, 110 insertions(+), 1 deletion(-)
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 7712688608f4..c8038165b81f 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -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
diff --git a/arch/parisc/kernel/kprobes.c b/arch/parisc/kernel/kprobes.c
index 8b1977cd3eb9..d58960b33bda 100644
--- a/arch/parisc/kernel/kprobes.c
+++ b/arch/parisc/kernel/kprobes.c
@@ -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);
}
--
2.20.1
