uprobes: Add uprobe_task->dup_xol_work/dup_xol_addr (32473431) · Commits · 戴 / test

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>

include/linux/uprobes.h

+16 −5

Original line number	Diff line number	Diff line
		@@ -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 @@ enum uprobe_task_state {
		*/
		struct uprobe_task {
		enum uprobe_task_state state;

		union {
		struct {
		struct arch_uprobe_task autask;
		unsigned long vaddr;
		};

		struct return_instance *return_instances;
		unsigned int depth;
		struct uprobe *active_uprobe;
		struct {
		struct callback_head dup_xol_work;
		unsigned long dup_xol_addr;
		};
		};

		struct uprobe *active_uprobe;
		unsigned long xol_vaddr;
		unsigned long vaddr;

		struct return_instance *return_instances;
		unsigned int depth;
		};

		/*

kernel/events/uprobes.c

+4 −12

Original line number	Diff line number	Diff line
		@@ -1403,12 +1403,10 @@ static void uprobe_warn(struct task_struct t, const char msg)

		static void dup_xol_work(struct callback_head *work)
		{
		kfree(work);

		if (current->flags & PF_EXITING)
		return;

		if (!__create_xol_area(current->utask->vaddr))
		if (!__create_xol_area(current->utask->dup_xol_addr))
		uprobe_warn(current, "dup xol area");
		}

		@@ -1419,7 +1417,6 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
		{
		struct uprobe_task *utask = current->utask;
		struct mm_struct *mm = current->mm;
		struct callback_head *work;
		struct xol_area *area;

		t->utask = NULL;
		@@ -1441,14 +1438,9 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
		if (mm == t->mm)
		return;

		/* TODO: move it into the union in uprobe_task */
		work = kmalloc(sizeof(*work), GFP_KERNEL);
		if (!work)
		return uprobe_warn(t, "dup xol area");

		t->utask->vaddr = area->vaddr;
		init_task_work(work, dup_xol_work);
		task_work_add(t, work, true);
		t->utask->dup_xol_addr = area->vaddr;
		init_task_work(&t->utask->dup_xol_work, dup_xol_work);
		task_work_add(t, &t->utask->dup_xol_work, true);
		}

		/*

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