On Tue, Jul 07, 2015 at 03:23:10AM +0200, Oleg Nesterov wrote:
> 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.
>
> Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: Anton Arapov <ara...@gmail.com>
> ---
> arch/x86/kernel/uprobes.c | 3 ++-
> include/linux/uprobes.h | 7 ++++++-
> kernel/events/uprobes.c | 9 ++++++---
> 3 files changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> index 9d5f570..67eb168 100644
> --- a/arch/x86/kernel/uprobes.c
> +++ b/arch/x86/kernel/uprobes.c
> @@ -994,7 +994,8 @@ 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
> --- 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
> --- 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;
> }
> --
> 1.5.5.1
>
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