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    SubjectRe: [PATCH v2 10/11] uprobes: Add the "enum rp_check ctx" arg to arch_uretprobe_is_alive()
    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 <oleg@redhat.com>
    Acked-by: Anton Arapov <arapov@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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