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

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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>
This commit is contained in:
Peter Zijlstra
2010-03-25 14:51:50 +01:00
committed by Ingo Molnar
parent 7c5ecaf766
commit faa4602e47
34 changed files with 9 additions and 3269 deletions
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36
arch/x86/kernel/step.c
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@@ -157,22 +157,6 @@ static int enable_single_step(struct task_struct *child)
return 1;
}
/*
* Install this value in MSR_IA32_DEBUGCTLMSR whenever child is running.
*/
static void write_debugctlmsr(struct task_struct *child, unsigned long val)
{
if (child->thread.debugctlmsr == val)
return;
child->thread.debugctlmsr = val;
if (child != current)
return;
update_debugctlmsr(val);
}
/*
* Enable single or block step.
*/
@@ -185,17 +169,9 @@ static void enable_step(struct task_struct *child, bool block)
* So noone should try to use debugger block stepping in a program
* that uses user-mode single stepping itself.
*/
if (enable_single_step(child) && block) {
set_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
write_debugctlmsr(child,
child->thread.debugctlmsr | DEBUGCTLMSR_BTF);
} else {
write_debugctlmsr(child,
child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
if (!child->thread.debugctlmsr)
clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
}
if (!enable_single_step(child))
return;
/* XXX */
}
void user_enable_single_step(struct task_struct *child)
@@ -213,11 +189,7 @@ void user_disable_single_step(struct task_struct *child)
/*
* Make sure block stepping (BTF) is disabled.
*/
write_debugctlmsr(child,
child->thread.debugctlmsr & ~DEBUGCTLMSR_BTF);
if (!child->thread.debugctlmsr)
clear_tsk_thread_flag(child, TIF_DEBUGCTLMSR);
/* XXX */
/* Always clear TIF_SINGLESTEP... */
clear_tsk_thread_flag(child, TIF_SINGLESTEP);