[PATCH v2 06/11] uprobes: Export struct return_instance, introduce arch_uretprobe_is_alive()

From: Oleg Nesterov
Date: Mon Jul 06 2015 - 21:26:12 EST


Add the new "weak" helper, arch_uretprobe_is_alive(), used by the next
patches. It should return true if this return_instance is still valid.
The arch agnostic version just always returns true.

The patch exports "struct return_instance" for the architectures which
want to override this hook. We can also cleanup prepare_uretprobe() if
we pass the new return_instance to arch_uretprobe_hijack_return_addr().

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
include/linux/uprobes.h | 10 ++++++++++
kernel/events/uprobes.c | 14 +++++---------
2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 60beb5d..50d2764 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -92,6 +92,15 @@ struct uprobe_task {
unsigned int depth;
};

+struct return_instance {
+ struct uprobe *uprobe;
+ unsigned long func;
+ unsigned long orig_ret_vaddr; /* original return address */
+ bool chained; /* true, if instance is nested */
+
+ struct return_instance *next; /* keep as stack */
+};
+
struct xol_area;

struct uprobes_state {
@@ -128,6 +137,7 @@ extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
+extern bool arch_uretprobe_is_alive(struct return_instance *ret, struct pt_regs *regs);
extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
void *src, unsigned long len);
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 98e4d97..1c71b62 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -86,15 +86,6 @@ struct uprobe {
struct arch_uprobe arch;
};

-struct return_instance {
- struct uprobe *uprobe;
- unsigned long func;
- unsigned long orig_ret_vaddr; /* original return address */
- bool chained; /* true, if instance is nested */
-
- struct return_instance *next; /* keep as stack */
-};
-
/*
* Execute out of line area: anonymous executable mapping installed
* by the probed task to execute the copy of the original instruction
@@ -1818,6 +1809,11 @@ bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
return false;
}

+bool __weak arch_uretprobe_is_alive(struct return_instance *ret, struct pt_regs *regs)
+{
+ return true;
+}
+
/*
* Run handler and ask thread to singlestep.
* Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
--
1.5.5.1

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