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, 382 deletions

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index a503b1fd04e5..f2fd3b80e565 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -2,9 +2,6 @@
 /*
  * Pentium III FXSR, SSE support
  *      Gareth Hughes <gareth@valinux.com>, May 2000
- *
- * BTS tracing
- *      Markus Metzger <markus.t.metzger@intel.com>, Dec 2007
  */
 
 #include <linux/kernel.h>
@@ -21,7 +18,6 @@
 #include <linux/audit.h>
 #include <linux/seccomp.h>
 #include <linux/signal.h>
-#include <linux/workqueue.h>
 #include <linux/perf_event.h>
 #include <linux/hw_breakpoint.h>
 
@@ -35,7 +31,6 @@
 #include <asm/desc.h>
 #include <asm/prctl.h>
 #include <asm/proto.h>
-#include <asm/ds.h>
 #include <asm/hw_breakpoint.h>
 
 #include "tls.h"
@@ -788,342 +783,6 @@ static int ioperm_get(struct task_struct *target,
                                    0, IO_BITMAP_BYTES);
 }
 
-#ifdef CONFIG_X86_PTRACE_BTS
-/*
- * A branch trace store context.
- *
- * Contexts may only be installed by ptrace_bts_config() and only for
- * ptraced tasks.
- *
- * Contexts are destroyed when the tracee is detached from the tracer.
- * The actual destruction work requires interrupts enabled, so the
- * work is deferred and will be scheduled during __ptrace_unlink().
- *
- * Contexts hold an additional task_struct reference on the traced
- * task, as well as a reference on the tracer's mm.
- *
- * Ptrace already holds a task_struct for the duration of ptrace operations,
- * but since destruction is deferred, it may be executed after both
- * tracer and tracee exited.
- */
-struct bts_context {
-        /* The branch trace handle. */
-        struct bts_tracer       *tracer;
-
-        /* The buffer used to store the branch trace and its size. */
-        void                    *buffer;
-        unsigned int            size;
-
-        /* The mm that paid for the above buffer. */
-        struct mm_struct        *mm;
-
-        /* The task this context belongs to. */
-        struct task_struct      *task;
-
-        /* The signal to send on a bts buffer overflow. */
-        unsigned int            bts_ovfl_signal;
-
-        /* The work struct to destroy a context. */
-        struct work_struct      work;
-};
-
-static int alloc_bts_buffer(struct bts_context *context, unsigned int size)
-{
-        void *buffer = NULL;
-        int err = -ENOMEM;
-
-        err = account_locked_memory(current->mm, current->signal->rlim, size);
-        if (err < 0)
-                return err;
-
-        buffer = kzalloc(size, GFP_KERNEL);
-        if (!buffer)
-                goto out_refund;
-
-        context->buffer = buffer;
-        context->size = size;
-        context->mm = get_task_mm(current);
-
-        return 0;
-
- out_refund:
-        refund_locked_memory(current->mm, size);
-        return err;
-}
-
-static inline void free_bts_buffer(struct bts_context *context)
-{
-        if (!context->buffer)
-                return;
-
-        kfree(context->buffer);
-        context->buffer = NULL;
-
-        refund_locked_memory(context->mm, context->size);
-        context->size = 0;
-
-        mmput(context->mm);
-        context->mm = NULL;
-}
-
-static void free_bts_context_work(struct work_struct *w)
-{
-        struct bts_context *context;
-
-        context = container_of(w, struct bts_context, work);
-
-        ds_release_bts(context->tracer);
-        put_task_struct(context->task);
-        free_bts_buffer(context);
-        kfree(context);
-}
-
-static inline void free_bts_context(struct bts_context *context)
-{
-        INIT_WORK(&context->work, free_bts_context_work);
-        schedule_work(&context->work);
-}
-
-static inline struct bts_context *alloc_bts_context(struct task_struct *task)
-{
-        struct bts_context *context = kzalloc(sizeof(*context), GFP_KERNEL);
-        if (context) {
-                context->task = task;
-                task->bts = context;
-
-                get_task_struct(task);
-        }
-
-        return context;
-}
-
-static int ptrace_bts_read_record(struct task_struct *child, size_t index,
-                                  struct bts_struct __user *out)
-{
-        struct bts_context *context;
-        const struct bts_trace *trace;
-        struct bts_struct bts;
-        const unsigned char *at;
-        int error;
-
-        context = child->bts;
-        if (!context)
-                return -ESRCH;
-
-        trace = ds_read_bts(context->tracer);
-        if (!trace)
-                return -ESRCH;
-
-        at = trace->ds.top - ((index + 1) * trace->ds.size);
-        if ((void *)at < trace->ds.begin)
-                at += (trace->ds.n * trace->ds.size);
-
-        if (!trace->read)
-                return -EOPNOTSUPP;
-
-        error = trace->read(context->tracer, at, &bts);
-        if (error < 0)
-                return error;
-
-        if (copy_to_user(out, &bts, sizeof(bts)))
-                return -EFAULT;
-
-        return sizeof(bts);
-}
-
-static int ptrace_bts_drain(struct task_struct *child,
-                            long size,
-                            struct bts_struct __user *out)
-{
-        struct bts_context *context;
-        const struct bts_trace *trace;
-        const unsigned char *at;
-        int error, drained = 0;
-
-        context = child->bts;
-        if (!context)
-                return -ESRCH;
-
-        trace = ds_read_bts(context->tracer);
-        if (!trace)
-                return -ESRCH;
-
-        if (!trace->read)
-                return -EOPNOTSUPP;
-
-        if (size < (trace->ds.top - trace->ds.begin))
-                return -EIO;
-
-        for (at = trace->ds.begin; (void *)at < trace->ds.top;
-             out++, drained++, at += trace->ds.size) {
-                struct bts_struct bts;
-
-                error = trace->read(context->tracer, at, &bts);
-                if (error < 0)
-                        return error;
-
-                if (copy_to_user(out, &bts, sizeof(bts)))
-                        return -EFAULT;
-        }
-
-        memset(trace->ds.begin, 0, trace->ds.n * trace->ds.size);
-
-        error = ds_reset_bts(context->tracer);
-        if (error < 0)
-                return error;
-
-        return drained;
-}
-
-static int ptrace_bts_config(struct task_struct *child,
-                             long cfg_size,
-                             const struct ptrace_bts_config __user *ucfg)
-{
-        struct bts_context *context;
-        struct ptrace_bts_config cfg;
-        unsigned int flags = 0;
-
-        if (cfg_size < sizeof(cfg))
-                return -EIO;
-
-        if (copy_from_user(&cfg, ucfg, sizeof(cfg)))
-                return -EFAULT;
-
-        context = child->bts;
-        if (!context)
-                context = alloc_bts_context(child);
-        if (!context)
-                return -ENOMEM;
-
-        if (cfg.flags & PTRACE_BTS_O_SIGNAL) {
-                if (!cfg.signal)
-                        return -EINVAL;
-
-                return -EOPNOTSUPP;
-                context->bts_ovfl_signal = cfg.signal;
-        }
-
-        ds_release_bts(context->tracer);
-        context->tracer = NULL;
-
-        if ((cfg.flags & PTRACE_BTS_O_ALLOC) && (cfg.size != context->size)) {
-                int err;
-
-                free_bts_buffer(context);
-                if (!cfg.size)
-                        return 0;
-
-                err = alloc_bts_buffer(context, cfg.size);
-                if (err < 0)
-                        return err;
-        }
-
-        if (cfg.flags & PTRACE_BTS_O_TRACE)
-                flags |= BTS_USER;
-
-        if (cfg.flags & PTRACE_BTS_O_SCHED)
-                flags |= BTS_TIMESTAMPS;
-
-        context->tracer =
-                ds_request_bts_task(child, context->buffer, context->size,
-                                    NULL, (size_t)-1, flags);
-        if (unlikely(IS_ERR(context->tracer))) {
-                int error = PTR_ERR(context->tracer);
-
-                free_bts_buffer(context);
-                context->tracer = NULL;
-                return error;
-        }
-
-        return sizeof(cfg);
-}
-
-static int ptrace_bts_status(struct task_struct *child,
-                             long cfg_size,
-                             struct ptrace_bts_config __user *ucfg)
-{
-        struct bts_context *context;
-        const struct bts_trace *trace;
-        struct ptrace_bts_config cfg;
-
-        context = child->bts;
-        if (!context)
-                return -ESRCH;
-
-        if (cfg_size < sizeof(cfg))
-                return -EIO;
-
-        trace = ds_read_bts(context->tracer);
-        if (!trace)
-                return -ESRCH;
-
-        memset(&cfg, 0, sizeof(cfg));
-        cfg.size        = trace->ds.end - trace->ds.begin;
-        cfg.signal      = context->bts_ovfl_signal;
-        cfg.bts_size    = sizeof(struct bts_struct);
-
-        if (cfg.signal)
-                cfg.flags |= PTRACE_BTS_O_SIGNAL;
-
-        if (trace->ds.flags & BTS_USER)
-                cfg.flags |= PTRACE_BTS_O_TRACE;
-
-        if (trace->ds.flags & BTS_TIMESTAMPS)
-                cfg.flags |= PTRACE_BTS_O_SCHED;
-
-        if (copy_to_user(ucfg, &cfg, sizeof(cfg)))
-                return -EFAULT;
-
-        return sizeof(cfg);
-}
-
-static int ptrace_bts_clear(struct task_struct *child)
-{
-        struct bts_context *context;
-        const struct bts_trace *trace;
-
-        context = child->bts;
-        if (!context)
-                return -ESRCH;
-
-        trace = ds_read_bts(context->tracer);
-        if (!trace)
-                return -ESRCH;
-
-        memset(trace->ds.begin, 0, trace->ds.n * trace->ds.size);
-
-        return ds_reset_bts(context->tracer);
-}
-
-static int ptrace_bts_size(struct task_struct *child)
-{
-        struct bts_context *context;
-        const struct bts_trace *trace;
-
-        context = child->bts;
-        if (!context)
-                return -ESRCH;
-
-        trace = ds_read_bts(context->tracer);
-        if (!trace)
-                return -ESRCH;
-
-        return (trace->ds.top - trace->ds.begin) / trace->ds.size;
-}
-
-/*
- * Called from __ptrace_unlink() after the child has been moved back
- * to its original parent.
- */
-void ptrace_bts_untrace(struct task_struct *child)
-{
-        if (unlikely(child->bts)) {
-                free_bts_context(child->bts);
-                child->bts = NULL;
-        }
-}
-#endif /* CONFIG_X86_PTRACE_BTS */
-
 /*
  * Called by kernel/ptrace.c when detaching..
  *
@@ -1251,39 +910,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                 break;
 #endif
 
-        /*
-         * These bits need more cooking - not enabled yet:
-         */
-#ifdef CONFIG_X86_PTRACE_BTS
-        case PTRACE_BTS_CONFIG:
-                ret = ptrace_bts_config
-                        (child, data, (struct ptrace_bts_config __user *)addr);
-                break;
-
-        case PTRACE_BTS_STATUS:
-                ret = ptrace_bts_status
-                        (child, data, (struct ptrace_bts_config __user *)addr);
-                break;
-
-        case PTRACE_BTS_SIZE:
-                ret = ptrace_bts_size(child);
-                break;
-
-        case PTRACE_BTS_GET:
-                ret = ptrace_bts_read_record
-                        (child, data, (struct bts_struct __user *) addr);
-                break;
-
-        case PTRACE_BTS_CLEAR:
-                ret = ptrace_bts_clear(child);
-                break;
-
-        case PTRACE_BTS_DRAIN:
-                ret = ptrace_bts_drain
-                        (child, data, (struct bts_struct __user *) addr);
-                break;
-#endif /* CONFIG_X86_PTRACE_BTS */
-
         default:
                 ret = ptrace_request(child, request, addr, data);
                 break;
@@ -1543,14 +1169,6 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 
         case PTRACE_GET_THREAD_AREA:
         case PTRACE_SET_THREAD_AREA:
-#ifdef CONFIG_X86_PTRACE_BTS
-        case PTRACE_BTS_CONFIG:
-        case PTRACE_BTS_STATUS:
-        case PTRACE_BTS_SIZE:
-        case PTRACE_BTS_GET:
-        case PTRACE_BTS_CLEAR:
-        case PTRACE_BTS_DRAIN:
-#endif /* CONFIG_X86_PTRACE_BTS */
                 return arch_ptrace(child, request, addr, data);
 
         default: