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>
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@ -26,6 +26,7 @@
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#include <linux/errno.h>
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#include <linux/errno.h>
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#include <linux/rbtree.h>
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#include <linux/rbtree.h>
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#include <linux/types.h>
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struct vm_area_struct;
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struct vm_area_struct;
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struct mm_struct;
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struct mm_struct;
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@ -72,14 +73,24 @@ enum uprobe_task_state {
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*/
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*/
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struct uprobe_task {
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struct uprobe_task {
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enum uprobe_task_state state;
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enum uprobe_task_state state;
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struct arch_uprobe_task autask;
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union {
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struct {
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struct arch_uprobe_task autask;
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unsigned long vaddr;
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};
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struct {
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struct callback_head dup_xol_work;
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unsigned long dup_xol_addr;
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};
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};
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struct uprobe *active_uprobe;
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unsigned long xol_vaddr;
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struct return_instance *return_instances;
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struct return_instance *return_instances;
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unsigned int depth;
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unsigned int depth;
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struct uprobe *active_uprobe;
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unsigned long xol_vaddr;
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unsigned long vaddr;
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};
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};
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/*
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/*
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@ -1403,12 +1403,10 @@ static void uprobe_warn(struct task_struct *t, const char *msg)
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static void dup_xol_work(struct callback_head *work)
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static void dup_xol_work(struct callback_head *work)
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{
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{
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kfree(work);
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if (current->flags & PF_EXITING)
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if (current->flags & PF_EXITING)
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return;
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return;
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if (!__create_xol_area(current->utask->vaddr))
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if (!__create_xol_area(current->utask->dup_xol_addr))
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uprobe_warn(current, "dup xol area");
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uprobe_warn(current, "dup xol area");
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}
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}
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@ -1419,7 +1417,6 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
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{
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{
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struct uprobe_task *utask = current->utask;
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struct uprobe_task *utask = current->utask;
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struct mm_struct *mm = current->mm;
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struct mm_struct *mm = current->mm;
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struct callback_head *work;
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struct xol_area *area;
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struct xol_area *area;
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t->utask = NULL;
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t->utask = NULL;
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@ -1441,14 +1438,9 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags)
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if (mm == t->mm)
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if (mm == t->mm)
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return;
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return;
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/* TODO: move it into the union in uprobe_task */
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t->utask->dup_xol_addr = area->vaddr;
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work = kmalloc(sizeof(*work), GFP_KERNEL);
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init_task_work(&t->utask->dup_xol_work, dup_xol_work);
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if (!work)
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task_work_add(t, &t->utask->dup_xol_work, true);
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return uprobe_warn(t, "dup xol area");
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t->utask->vaddr = area->vaddr;
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init_task_work(work, dup_xol_work);
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task_work_add(t, work, true);
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}
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}
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/*
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/*
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