Messages in this thread | | | Date | Mon, 11 Nov 2013 10:43:58 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] uprobes: Add uprobe_task->dup_work/dup_addr |
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(2013/11/09 4:00), Oleg Nesterov wrote: > uprobe_task->vaddr is a bit strange. First of all it is not really > needed, we can move it into arch_uprobe_task. 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. This means it is safe to reuse both in UTASK_RUNNING > state. > > 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_addr which can be used instead ->vaddr, and ->dup_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.
OK, those are used in the different phase as a scratchpad.
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Thanks!
> --- > include/linux/uprobes.h | 21 ++++++++++++++++----- > kernel/events/uprobes.c | 16 ++++------------ > 2 files changed, 20 insertions(+), 17 deletions(-) > > diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h > index 319eae7..366b8b2 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 @@ enum uprobe_task_state { > */ > struct uprobe_task { > enum uprobe_task_state state; > - struct arch_uprobe_task autask; > > - struct return_instance *return_instances; > - unsigned int depth; > - struct uprobe *active_uprobe; > + union { > + struct { > + struct arch_uprobe_task autask; > + unsigned long vaddr; > + }; > + > + struct { > + struct callback_head dup_work; > + unsigned long dup_addr; > + }; > + }; > > + struct uprobe *active_uprobe; > unsigned long xol_vaddr; > - unsigned long vaddr; > + > + struct return_instance *return_instances; > + unsigned int depth; > }; > > /* > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 24b7d6c..2546a7b 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -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_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_addr = area->vaddr; > + init_task_work(&t->utask->dup_work, dup_xol_work); > + task_work_add(t, &t->utask->dup_work, true); > } > > /* >
-- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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