On Thu, 1 May 2014, Andi Kleen wrote:
> > diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> > index 1e96c3628bf2..a03b1e9d2de3 100644
> > --- a/arch/x86/kernel/entry_64.S
> > +++ b/arch/x86/kernel/entry_64.S
> > @@ -615,6 +615,7 @@ GLOBAL(system_call_after_swapgs)
> > movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
> > movq %rcx,RIP-ARGOFFSET(%rsp)
> > CFI_REL_OFFSET rip,RIP-ARGOFFSET
> > + movw $0, TI_kgr_in_progress+THREAD_INFO(%rsp,RIP-ARGOFFSET)
>
> Better use 4 bytes. This has the potential to cause an expensive
> Length Changing Prefixes Stall on Intel CPUs.
Patch 16/16 converts this to a single bit within TI_flags.
> > +static int kgr_init_ftrace_ops(const struct kgr_patch_fun *patch_fun)
> > +{
> > + struct kgr_loc_caches *caches;
> > + unsigned long fentry_loc;
> > +
> > + /*
> > + * Initialize the ftrace_ops->private with pointers to the fentry
> > + * sites of both old and new functions. This is used as a
> > + * redirection target in the per-arch stubs.
> > + *
> > + * Beware! -- freeing (once unloading will be implemented)
> > + * will require synchronize_sched() etc.
> > + */
> > +
> > + caches = kmalloc(sizeof(*caches), GFP_KERNEL);
> > + if (!caches) {
> > + kgr_debug("kgr: unable to allocate fentry caches\n");
> > + return -ENOMEM;
> > + }
>
> All the error paths in this function leak memory.
Gah, good catch, thanks a lot.
--
Jiri Kosina
SUSE Labs
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