lkml.org 
[lkml]   [2014]   [May]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC 03/16] kgr: initial code
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


\
 
 \ /
  Last update: 2014-05-01 23:01    [W:0.354 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site