uprobes: Add uprobe_task->dup_xol_work/dup_xol_addr
uprobe_task->vaddr is a bit strange. The generic code uses it only
to pass the additional argument to arch_uprobe_pre_xol(), and since
it is always equal to instruction_pointer() this looks even more
strange.
And both utask->vaddr and and utask->autask have the same scope,
they only have the meaning when the task executes the probed insn
out-of-line, so it is safe to reuse both in UTASK_RUNNING state.
This all means that logically ->vaddr belongs to arch_uprobe_task
and we should probably move it there, arch_uprobe_pre_xol() can
record instruction_pointer() itself.
OTOH, it is also used by uprobe_copy_process() and dup_xol_work()
for another purpose, this doesn't look clean and doesn't allow to
move this member into arch_uprobe_task.
This patch adds the union with 2 anonymous structs into uprobe_task.
The first struct is autask + vaddr, this way we "almost" move vaddr
into autask.
The second struct has 2 new members for uprobe_copy_process() paths:
->dup_xol_addr which can be used instead ->vaddr, and ->dup_xol_work
which can be used to avoid kmalloc() and simplify the code.
Note that this union will likely have another member(s), we need
something like "private_data_for_handlers" so that the tracing
handlers could use it to communicate with call_fetch() methods.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 319eae7..2225542 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -26,6 +26,7 @@
#include <linux/errno.h>
#include <linux/rbtree.h>
+#include <linux/types.h>
struct vm_area_struct;
struct mm_struct;
@@ -72,14 +73,24 @@
*/
struct uprobe_task {
enum uprobe_task_state state;
- struct arch_uprobe_task autask;
+
+ union {
+ struct {
+ struct arch_uprobe_task autask;
+ unsigned long vaddr;
+ };
+
+ struct {
+ struct callback_head dup_xol_work;
+ unsigned long dup_xol_addr;
+ };
+ };
+
+ struct uprobe *active_uprobe;
+ unsigned long xol_vaddr;
struct return_instance *return_instances;
unsigned int depth;
- struct uprobe *active_uprobe;
-
- unsigned long xol_vaddr;
- unsigned long vaddr;
};
/*