x86, perf, bts, mm: Delete the never used BTS-ptrace code

Support for the PMU's BTS features has been upstreamed in
v2.6.32, but we still have the old and disabled ptrace-BTS,
as Linus noticed it not so long ago.

It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without
regard for other uses (perf) and doesn't provide the flexibility
needed for perf either.

Its users are ptrace-block-step and ptrace-bts, since ptrace-bts
was never used and ptrace-block-step can be implemented using a
much simpler approach.

So axe all 3000 lines of it. That includes the *locked_memory*()
APIs in mm/mlock.c as well.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20100325135413.938004390@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 0 insertions, 3 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 4799c5f0e6d0..d67f1dbfbe03 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1108,9 +1108,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->memcg_batch.do_batch = 0;
         p->memcg_batch.memcg = NULL;
 #endif
-
-        p->bts = NULL;
-
         p->stack_start = stack_start;
 
         /* Perform scheduler related setup. Assign this task to a CPU. */