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authorOleg Nesterov <oleg@redhat.com>2013-11-08 18:52:21 +0100
committerOleg Nesterov <oleg@redhat.com>2013-11-20 16:30:57 +0100
commit3247343118daa73f2b94b7fa565425d1d9f9ac84 (patch)
treedb1b65941295431fbbb5cc8d822c0ebe0e0b6757 /kernel/events
parentcaea6cf52139116e43e615d87fcbf9823e197fdf (diff)
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>
Diffstat (limited to 'kernel/events')
-rw-r--r--kernel/events/uprobes.c16
1 files changed, 4 insertions, 12 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 24b7d6ca871b..df4ef0971266 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_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);
}
/*