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>

9 files changed, 0 insertions, 444 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. */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 42ad8ae729a0..9fb51237b18c 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -76,7 +76,6 @@ void __ptrace_unlink(struct task_struct *child)
         child->parent = child->real_parent;
         list_del_init(&child->ptrace_entry);
 
-        arch_ptrace_untrace(child);
         if (task_is_traced(child))
                 ptrace_untrace(child);
 }
diff --git a/kernel/sched.c b/kernel/sched.c
index 9ab3cd7858d3..117b7cad31b3 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2077,49 +2077,6 @@ migrate_task(struct task_struct *p, int dest_cpu, struct migration_req *req)
 }
 
 /*
- * wait_task_context_switch -   wait for a thread to complete at least one
- *                              context switch.
- *
- * @p must not be current.
- */
-void wait_task_context_switch(struct task_struct *p)
-{
-        unsigned long nvcsw, nivcsw, flags;
-        int running;
-        struct rq *rq;
-
-        nvcsw   = p->nvcsw;
-        nivcsw  = p->nivcsw;
-        for (;;) {
-                /*
-                 * The runqueue is assigned before the actual context
-                 * switch. We need to take the runqueue lock.
-                 *
-                 * We could check initially without the lock but it is
-                 * very likely that we need to take the lock in every
-                 * iteration.
-                 */
-                rq = task_rq_lock(p, &flags);
-                running = task_running(rq, p);
-                task_rq_unlock(rq, &flags);
-
-                if (likely(!running))
-                        break;
-                /*
-                 * The switch count is incremented before the actual
-                 * context switch. We thus wait for two switches to be
-                 * sure at least one completed.
-                 */
-                if ((p->nvcsw - nvcsw) > 1)
-                        break;
-                if ((p->nivcsw - nivcsw) > 1)
-                        break;
-
-                cpu_relax();
-        }
-}
-
-/*
  * wait_task_inactive - wait for a thread to unschedule.
  *
  * If @match_state is nonzero, it's the @p->state value just checked and
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 13e13d428cd3..8b1797c4545b 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -44,9 +44,6 @@ config HAVE_FTRACE_MCOUNT_RECORD
         help
           See Documentation/trace/ftrace-design.txt
 
-config HAVE_HW_BRANCH_TRACER
-        bool
-
 config HAVE_SYSCALL_TRACEPOINTS
         bool
         help
@@ -374,14 +371,6 @@ config STACK_TRACER
 
           Say N if unsure.
 
-config HW_BRANCH_TRACER
-        depends on HAVE_HW_BRANCH_TRACER
-        bool "Trace hw branches"
-        select GENERIC_TRACER
-        help
-          This tracer records all branches on the system in a circular
-          buffer, giving access to the last N branches for each cpu.
-
 config KMEMTRACE
         bool "Trace SLAB allocations"
         select GENERIC_TRACER
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 78edc6490038..ffb1a5b0550e 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -41,7 +41,6 @@ obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
 obj-$(CONFIG_BOOT_TRACER) += trace_boot.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += trace_functions_graph.o
 obj-$(CONFIG_TRACE_BRANCH_PROFILING) += trace_branch.o
-obj-$(CONFIG_HW_BRANCH_TRACER) += trace_hw_branches.o
 obj-$(CONFIG_KMEMTRACE) += kmemtrace.o
 obj-$(CONFIG_WORKQUEUE_TRACER) += trace_workqueue.o
 obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 2825ef2c0b15..bec2c973ff0c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -34,7 +34,6 @@ enum trace_type {
         TRACE_GRAPH_RET,
         TRACE_GRAPH_ENT,
         TRACE_USER_STACK,
-        TRACE_HW_BRANCHES,
         TRACE_KMEM_ALLOC,
         TRACE_KMEM_FREE,
         TRACE_BLK,
@@ -229,7 +228,6 @@ extern void __ftrace_bad_type(void);
                           TRACE_GRAPH_ENT);             \
                 IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
                           TRACE_GRAPH_RET);             \
-                IF_ASSIGN(var, ent, struct hw_branch_entry, TRACE_HW_BRANCHES);\
                 IF_ASSIGN(var, ent, struct kmemtrace_alloc_entry,       \
                           TRACE_KMEM_ALLOC);    \
                 IF_ASSIGN(var, ent, struct kmemtrace_free_entry,        \
@@ -467,8 +465,6 @@ extern int trace_selftest_startup_sysprof(struct tracer *trace,
                                                struct trace_array *tr);
 extern int trace_selftest_startup_branch(struct tracer *trace,
                                          struct trace_array *tr);
-extern int trace_selftest_startup_hw_branches(struct tracer *trace,
-                                              struct trace_array *tr);
 extern int trace_selftest_startup_ksym(struct tracer *trace,
                                          struct trace_array *tr);
 #endif /* CONFIG_FTRACE_STARTUP_TEST */
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index c16a08f399df..dc008c1240da 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -318,18 +318,6 @@ FTRACE_ENTRY(branch, trace_branch,
                  __entry->func, __entry->file, __entry->correct)
 );
 
-FTRACE_ENTRY(hw_branch, hw_branch_entry,
-
-        TRACE_HW_BRANCHES,
-
-        F_STRUCT(
-                __field(        u64,    from    )
-                __field(        u64,    to      )
-        ),
-
-        F_printk("from: %llx to: %llx", __entry->from, __entry->to)
-);
-
 FTRACE_ENTRY(kmem_alloc, kmemtrace_alloc_entry,
 
         TRACE_KMEM_ALLOC,
diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c
deleted file mode 100644
index 7b97000745f5..000000000000
--- a/kernel/trace/trace_hw_branches.c
+++ /dev/null
@@ -1,312 +0,0 @@
-/*
- * h/w branch tracer for x86 based on BTS
- *
- * Copyright (C) 2008-2009 Intel Corporation.
- * Markus Metzger <markus.t.metzger@gmail.com>, 2008-2009
- */
-#include <linux/kallsyms.h>
-#include <linux/debugfs.h>
-#include <linux/ftrace.h>
-#include <linux/module.h>
-#include <linux/cpu.h>
-#include <linux/smp.h>
-#include <linux/fs.h>
-
-#include <asm/ds.h>
-
-#include "trace_output.h"
-#include "trace.h"
-
-
-#define BTS_BUFFER_SIZE (1 << 13)
-
-static DEFINE_PER_CPU(struct bts_tracer *, hwb_tracer);
-static DEFINE_PER_CPU(unsigned char[BTS_BUFFER_SIZE], hwb_buffer);
-
-#define this_tracer per_cpu(hwb_tracer, smp_processor_id())
-
-static int trace_hw_branches_enabled __read_mostly;
-static int trace_hw_branches_suspended __read_mostly;
-static struct trace_array *hw_branch_trace __read_mostly;
-
-
-static void bts_trace_init_cpu(int cpu)
-{
-        per_cpu(hwb_tracer, cpu) =
-                ds_request_bts_cpu(cpu, per_cpu(hwb_buffer, cpu),
-                                   BTS_BUFFER_SIZE, NULL, (size_t)-1,
-                                   BTS_KERNEL);
-
-        if (IS_ERR(per_cpu(hwb_tracer, cpu)))
-                per_cpu(hwb_tracer, cpu) = NULL;
-}
-
-static int bts_trace_init(struct trace_array *tr)
-{
-        int cpu;
-
-        hw_branch_trace = tr;
-        trace_hw_branches_enabled = 0;
-
-        get_online_cpus();
-        for_each_online_cpu(cpu) {
-                bts_trace_init_cpu(cpu);
-
-                if (likely(per_cpu(hwb_tracer, cpu)))
-                        trace_hw_branches_enabled = 1;
-        }
-        trace_hw_branches_suspended = 0;
-        put_online_cpus();
-
-        /* If we could not enable tracing on a single cpu, we fail. */
-        return trace_hw_branches_enabled ? 0 : -EOPNOTSUPP;
-}
-
-static void bts_trace_reset(struct trace_array *tr)
-{
-        int cpu;
-
-        get_online_cpus();
-        for_each_online_cpu(cpu) {
-                if (likely(per_cpu(hwb_tracer, cpu))) {
-                        ds_release_bts(per_cpu(hwb_tracer, cpu));
-                        per_cpu(hwb_tracer, cpu) = NULL;
-                }
-        }
-        trace_hw_branches_enabled = 0;
-        trace_hw_branches_suspended = 0;
-        put_online_cpus();
-}
-
-static void bts_trace_start(struct trace_array *tr)
-{
-        int cpu;
-
-        get_online_cpus();
-        for_each_online_cpu(cpu)
-                if (likely(per_cpu(hwb_tracer, cpu)))
-                        ds_resume_bts(per_cpu(hwb_tracer, cpu));
-        trace_hw_branches_suspended = 0;
-        put_online_cpus();
-}
-
-static void bts_trace_stop(struct trace_array *tr)
-{
-        int cpu;
-
-        get_online_cpus();
-        for_each_online_cpu(cpu)
-                if (likely(per_cpu(hwb_tracer, cpu)))
-                        ds_suspend_bts(per_cpu(hwb_tracer, cpu));
-        trace_hw_branches_suspended = 1;
-        put_online_cpus();
-}
-
-static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
-                                     unsigned long action, void *hcpu)
-{
-        int cpu = (long)hcpu;
-
-        switch (action) {
-        case CPU_ONLINE:
-        case CPU_DOWN_FAILED:
-                /* The notification is sent with interrupts enabled. */
-                if (trace_hw_branches_enabled) {
-                        bts_trace_init_cpu(cpu);
-
-                        if (trace_hw_branches_suspended &&
-                            likely(per_cpu(hwb_tracer, cpu)))
-                                ds_suspend_bts(per_cpu(hwb_tracer, cpu));
-                }
-                break;
-
-        case CPU_DOWN_PREPARE:
-                /* The notification is sent with interrupts enabled. */
-                if (likely(per_cpu(hwb_tracer, cpu))) {
-                        ds_release_bts(per_cpu(hwb_tracer, cpu));
-                        per_cpu(hwb_tracer, cpu) = NULL;
-                }
-        }
-
-        return NOTIFY_DONE;
-}
-
-static struct notifier_block bts_hotcpu_notifier __cpuinitdata = {
-        .notifier_call = bts_hotcpu_handler
-};
-
-static void bts_trace_print_header(struct seq_file *m)
-{
-        seq_puts(m, "# CPU#        TO  <-  FROM\n");
-}
-
-static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
-{
-        unsigned long symflags = TRACE_ITER_SYM_OFFSET;
-        struct trace_entry *entry = iter->ent;
-        struct trace_seq *seq = &iter->seq;
-        struct hw_branch_entry *it;
-
-        trace_assign_type(it, entry);
-
-        if (entry->type == TRACE_HW_BRANCHES) {
-                if (trace_seq_printf(seq, "%4d  ", iter->cpu) &&
-                    seq_print_ip_sym(seq, it->to, symflags) &&
-                    trace_seq_printf(seq, "\t  <-  ") &&
-                    seq_print_ip_sym(seq, it->from, symflags) &&
-                    trace_seq_printf(seq, "\n"))
-                        return TRACE_TYPE_HANDLED;
-                return TRACE_TYPE_PARTIAL_LINE;
-        }
-        return TRACE_TYPE_UNHANDLED;
-}
-
-void trace_hw_branch(u64 from, u64 to)
-{
-        struct ftrace_event_call *call = &event_hw_branch;
-        struct trace_array *tr = hw_branch_trace;
-        struct ring_buffer_event *event;
-        struct ring_buffer *buf;
-        struct hw_branch_entry *entry;
-        unsigned long irq1;
-        int cpu;
-
-        if (unlikely(!tr))
-                return;
-
-        if (unlikely(!trace_hw_branches_enabled))
-                return;
-
-        local_irq_save(irq1);
-        cpu = raw_smp_processor_id();
-        if (atomic_inc_return(&tr->data[cpu]->disabled) != 1)
-                goto out;
-
-        buf = tr->buffer;
-        event = trace_buffer_lock_reserve(buf, TRACE_HW_BRANCHES,
-                                          sizeof(*entry), 0, 0);
-        if (!event)
-                goto out;
-        entry   = ring_buffer_event_data(event);
-        tracing_generic_entry_update(&entry->ent, 0, from);
-        entry->ent.type = TRACE_HW_BRANCHES;
-        entry->from = from;
-        entry->to   = to;
-        if (!filter_check_discard(call, entry, buf, event))
-                trace_buffer_unlock_commit(buf, event, 0, 0);
-
- out:
-        atomic_dec(&tr->data[cpu]->disabled);
-        local_irq_restore(irq1);
-}
-
-static void trace_bts_at(const struct bts_trace *trace, void *at)
-{
-        struct bts_struct bts;
-        int err = 0;
-
-        WARN_ON_ONCE(!trace->read);
-        if (!trace->read)
-                return;
-
-        err = trace->read(this_tracer, at, &bts);
-        if (err < 0)
-                return;
-
-        switch (bts.qualifier) {
-        case BTS_BRANCH:
-                trace_hw_branch(bts.variant.lbr.from, bts.variant.lbr.to);
-                break;
-        }
-}
-
-/*
- * Collect the trace on the current cpu and write it into the ftrace buffer.
- *
- * pre: tracing must be suspended on the current cpu
- */
-static void trace_bts_cpu(void *arg)
-{
-        struct trace_array *tr = (struct trace_array *)arg;
-        const struct bts_trace *trace;
-        unsigned char *at;
-
-        if (unlikely(!tr))
-                return;
-
-        if (unlikely(atomic_read(&tr->data[raw_smp_processor_id()]->disabled)))
-                return;
-
-        if (unlikely(!this_tracer))
-                return;
-
-        trace = ds_read_bts(this_tracer);
-        if (!trace)
-                return;
-
-        for (at = trace->ds.top; (void *)at < trace->ds.end;
-             at += trace->ds.size)
-                trace_bts_at(trace, at);
-
-        for (at = trace->ds.begin; (void *)at < trace->ds.top;
-             at += trace->ds.size)
-                trace_bts_at(trace, at);
-}
-
-static void trace_bts_prepare(struct trace_iterator *iter)
-{
-        int cpu;
-
-        get_online_cpus();
-        for_each_online_cpu(cpu)
-                if (likely(per_cpu(hwb_tracer, cpu)))
-                        ds_suspend_bts(per_cpu(hwb_tracer, cpu));
-        /*
-         * We need to collect the trace on the respective cpu since ftrace
-         * implicitly adds the record for the current cpu.
-         * Once that is more flexible, we could collect the data from any cpu.
-         */
-        on_each_cpu(trace_bts_cpu, iter->tr, 1);
-
-        for_each_online_cpu(cpu)
-                if (likely(per_cpu(hwb_tracer, cpu)))
-                        ds_resume_bts(per_cpu(hwb_tracer, cpu));
-        put_online_cpus();
-}
-
-static void trace_bts_close(struct trace_iterator *iter)
-{
-        tracing_reset_online_cpus(iter->tr);
-}
-
-void trace_hw_branch_oops(void)
-{
-        if (this_tracer) {
-                ds_suspend_bts_noirq(this_tracer);
-                trace_bts_cpu(hw_branch_trace);
-                ds_resume_bts_noirq(this_tracer);
-        }
-}
-
-struct tracer bts_tracer __read_mostly =
-{
-        .name           = "hw-branch-tracer",
-        .init           = bts_trace_init,
-        .reset          = bts_trace_reset,
-        .print_header   = bts_trace_print_header,
-        .print_line     = bts_trace_print_line,
-        .start          = bts_trace_start,
-        .stop           = bts_trace_stop,
-        .open           = trace_bts_prepare,
-        .close          = trace_bts_close,
-#ifdef CONFIG_FTRACE_SELFTEST
-        .selftest       = trace_selftest_startup_hw_branches,
-#endif /* CONFIG_FTRACE_SELFTEST */
-};
-
-__init static int init_bts_trace(void)
-{
-        register_hotcpu_notifier(&bts_hotcpu_notifier);
-        return register_tracer(&bts_tracer);
-}
-device_initcall(init_bts_trace);
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 280fea470d67..a7084e7c0427 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -16,7 +16,6 @@ static inline int trace_valid_entry(struct trace_entry *entry)
         case TRACE_BRANCH:
         case TRACE_GRAPH_ENT:
         case TRACE_GRAPH_RET:
-        case TRACE_HW_BRANCHES:
         case TRACE_KSYM:
                 return 1;
         }
@@ -754,62 +753,6 @@ trace_selftest_startup_branch(struct tracer *trace, struct trace_array *tr)
 }
 #endif /* CONFIG_BRANCH_TRACER */
 
-#ifdef CONFIG_HW_BRANCH_TRACER
-int
-trace_selftest_startup_hw_branches(struct tracer *trace,
-                                   struct trace_array *tr)
-{
-        struct trace_iterator *iter;
-        struct tracer tracer;
-        unsigned long count;
-        int ret;
-
-        if (!trace->open) {
-                printk(KERN_CONT "missing open function...");
-                return -1;
-        }
-
-        ret = tracer_init(trace, tr);
-        if (ret) {
-                warn_failed_init_tracer(trace, ret);
-                return ret;
-        }
-
-        /*
-         * The hw-branch tracer needs to collect the trace from the various
-         * cpu trace buffers - before tracing is stopped.
-         */
-        iter = kzalloc(sizeof(*iter), GFP_KERNEL);
-        if (!iter)
-                return -ENOMEM;
-
-        memcpy(&tracer, trace, sizeof(tracer));
-
-        iter->trace = &tracer;
-        iter->tr = tr;
-        iter->pos = -1;
-        mutex_init(&iter->mutex);
-
-        trace->open(iter);
-
-        mutex_destroy(&iter->mutex);
-        kfree(iter);
-
-        tracing_stop();
-
-        ret = trace_test_buffer(tr, &count);
-        trace->reset(tr);
-        tracing_start();
-
-        if (!ret && !count) {
-                printk(KERN_CONT "no entries found..");
-                ret = -1;
-        }
-
-        return ret;
-}
-#endif /* CONFIG_HW_BRANCH_TRACER */
-
 #ifdef CONFIG_KSYM_TRACER
 static int ksym_selftest_dummy;