uprobes: Add the "enum rp_check ctx" arg to arch_uretprobe_is_alive()

arch/x86 doesn't care (so far), but as Pratyush Anand pointed
out other architectures might want why arch_uretprobe_is_alive()
was called and use different checks depending on the context.
Add the new argument to distinguish 2 callers.

Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134026.GA4779@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 58e9b84..acf8b90 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -986,7 +986,8 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs
        return -1;
 }
 
-bool arch_uretprobe_is_alive(struct return_instance *ret, struct pt_regs *regs)
+bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
+                               struct pt_regs *regs)
 {
        return regs->sp <= ret->stack;
 }

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 7ab6d2c..c0a5402 100644 (file)
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -102,6 +102,11 @@ struct return_instance {
        struct return_instance  *next;          /* keep as stack */
 };
 
+enum rp_check {
+       RP_CHECK_CALL,
+       RP_CHECK_RET,
+};
+
 struct xol_area;
 
 struct uprobes_state {
@@ -138,7 +143,7 @@ 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_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, 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 7e61c8c..df5661a 100644 (file)
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1514,7 +1514,9 @@ static unsigned long get_trampoline_vaddr(void)
 static void cleanup_return_instances(struct uprobe_task *utask, struct pt_regs *regs)
 {
        struct return_instance *ri = utask->return_instances;
-       while (ri && !arch_uretprobe_is_alive(ri, regs)) {
+       enum rp_check ctx = RP_CHECK_CALL;
+
+       while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) {
                ri = free_ret_instance(ri);
                utask->depth--;
        }
@@ -1805,7 +1807,7 @@ static void handle_trampoline(struct pt_regs *regs)
                 * could hit this trampoline on return. TODO: sigaltstack().
                 */
                next = find_next_ret_chain(ri);
-               valid = !next || arch_uretprobe_is_alive(next, regs);
+               valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs);
 
                instruction_pointer_set(regs, ri->orig_ret_vaddr);
                do {
@@ -1830,7 +1832,8 @@ 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)
+bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
+                                       struct pt_regs *regs)
 {
        return true;
 }