Remove lttng-ftrace integration
authorMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Mon, 2 Mar 2020 16:26:39 +0000 (11:26 -0500)
committerMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Wed, 4 Mar 2020 14:59:30 +0000 (09:59 -0500)
The lttng-ftrace integration (LTTNG_KERNEL_FUNCTION instrumentation
type) was unused for a while now. The "function" probing is actually
done with kprobes and kretprobes (LTTNG_KERNEL_KPROBE and
LTTNG_KERNEL_KRETPROBE).

Remove it so a use of kallsyms_lookup_name() can be removed as well.
Note that in the future we could add back this support by using
register_ftrace_function() which is exported to kernel modules, but
considering that we have not been using this code for a while,
just remove the implementation for now.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Kbuild.common
lttng-abi.c
lttng-events.c
lttng-events.h
probes/Kbuild
probes/lttng-ftrace.c [deleted file]
wrapper/ftrace.h [deleted file]

index e2934e20f4880d94266a7f3d1ca39682abd56a8b..09296e7032af804303e8eb8b3cc5dedff72ac3b7 100644 (file)
@@ -50,27 +50,6 @@ endif
 
 EXTRA_VERSION_PATCHES:=$(shell $(TOP_LTTNG_MODULES_DIR)/scripts/extra-version-patches.sh $(TOP_LTTNG_MODULES_DIR))
 
-# Starting with kernel 4.12, the ftrace header was moved to private headers
-# and as such is not available when building against distro headers instead
-# of the full kernel sources. In the situation, define LTTNG_FTRACE_MISSING_HEADER
-# so we can enable the compat code even if CONFIG_DYNAMIC_FTRACE is enabled.
-ifneq ($(CONFIG_DYNAMIC_FTRACE),)
-  ftrace_dep = $(srctree)/kernel/trace/trace.h
-  ftrace_dep_check = $(wildcard $(ftrace_dep))
-  have_ftrace_header = $(shell \
-    if [ $(VERSION) -ge 5 -o \( $(VERSION) -eq 4 -a $(PATCHLEVEL) -ge 12 \) ] ; then \
-      if [ -z "$(ftrace_dep_check)" ] ; then \
-        echo "no" ; \
-        exit ; \
-      fi; \
-    fi; \
-    echo "yes" ; \
-    )
-  ifeq ($(have_ftrace_header), no)
-    ccflags-y += -DLTTNG_FTRACE_MISSING_HEADER
-  endif
-endif
-
 mnt_ns_dep = $(srctree)/fs/mount.h
 ifeq ($(wildcard $(mnt_ns_dep)),)
     ccflags-y += -DLTTNG_MNT_NS_MISSING_HEADER
index 9d610e9346f53c3669b5ca2b5c7de46475eed6d0..b63e376413490693e00cc38c2aea96e5cdfc9acb 100644 (file)
@@ -1221,7 +1221,8 @@ int lttng_abi_create_event(struct file *channel_file,
                event_param->u.kprobe.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
                break;
        case LTTNG_KERNEL_FUNCTION:
-               event_param->u.ftrace.symbol_name[LTTNG_KERNEL_SYM_NAME_LEN - 1] = '\0';
+               WARN_ON_ONCE(1);
+               /* Not implemented. */
                break;
        default:
                break;
@@ -1372,9 +1373,8 @@ long lttng_channel_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
                                sizeof(uevent_param->u.kretprobe.symbol_name));
                        break;
                case LTTNG_KERNEL_FUNCTION:
-                       memcpy(uevent_param->u.ftrace.symbol_name,
-                                       old_uevent_param->u.ftrace.symbol_name,
-                                       sizeof(uevent_param->u.ftrace.symbol_name));
+                       WARN_ON_ONCE(1);
+                       /* Not implemented. */
                        break;
                default:
                        break;
index cc932bf61643d04095c5d198e297a153d2fbd7f7..a1c8445a20bbf9e86a22f408af109cb0421c04a4 100644 (file)
@@ -416,7 +416,6 @@ int lttng_event_enable(struct lttng_event *event)
                ret = -EINVAL;
                break;
        case LTTNG_KERNEL_KPROBE:
-       case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_NOOP:
                WRITE_ONCE(event->enabled, 1);
@@ -424,6 +423,7 @@ int lttng_event_enable(struct lttng_event *event)
        case LTTNG_KERNEL_KRETPROBE:
                ret = lttng_kretprobes_event_enable_state(event, 1);
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through. */
        default:
                WARN_ON_ONCE(1);
                ret = -EINVAL;
@@ -452,7 +452,6 @@ int lttng_event_disable(struct lttng_event *event)
                ret = -EINVAL;
                break;
        case LTTNG_KERNEL_KPROBE:
-       case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_NOOP:
                WRITE_ONCE(event->enabled, 0);
@@ -460,6 +459,7 @@ int lttng_event_disable(struct lttng_event *event)
        case LTTNG_KERNEL_KRETPROBE:
                ret = lttng_kretprobes_event_enable_state(event, 0);
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through. */
        default:
                WARN_ON_ONCE(1);
                ret = -EINVAL;
@@ -602,11 +602,11 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
        case LTTNG_KERNEL_KPROBE:
        case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_KRETPROBE:
-       case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_SYSCALL:
                event_name = event_param->name;
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through. */
        default:
                WARN_ON_ONCE(1);
                ret = -EINVAL;
@@ -729,27 +729,6 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
                list_add(&event_return->list, &chan->session->events);
                break;
        }
-       case LTTNG_KERNEL_FUNCTION:
-               /*
-                * Needs to be explicitly enabled after creation, since
-                * we may want to apply filters.
-                */
-               event->enabled = 0;
-               event->registered = 1;
-               /*
-                * Populate lttng_event structure before event
-                * registration.
-                */
-               smp_wmb();
-               ret = lttng_ftrace_register(event_name,
-                               event_param->u.ftrace.symbol_name,
-                               event);
-               if (ret) {
-                       goto register_error;
-               }
-               ret = try_module_get(event->desc->owner);
-               WARN_ON_ONCE(!ret);
-               break;
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_SYSCALL:
                /*
@@ -786,6 +765,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
                ret = try_module_get(event->desc->owner);
                WARN_ON_ONCE(!ret);
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
        default:
                WARN_ON_ONCE(1);
                ret = -EINVAL;
@@ -850,10 +830,10 @@ void register_event(struct lttng_event *event)
        case LTTNG_KERNEL_KPROBE:
        case LTTNG_KERNEL_UPROBE:
        case LTTNG_KERNEL_KRETPROBE:
-       case LTTNG_KERNEL_FUNCTION:
        case LTTNG_KERNEL_NOOP:
                ret = 0;
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
        default:
                WARN_ON_ONCE(1);
        }
@@ -887,10 +867,6 @@ int _lttng_event_unregister(struct lttng_event *event)
                lttng_kretprobes_unregister(event);
                ret = 0;
                break;
-       case LTTNG_KERNEL_FUNCTION:
-               lttng_ftrace_unregister(event);
-               ret = 0;
-               break;
        case LTTNG_KERNEL_SYSCALL:
                ret = lttng_syscall_filter_disable(event->chan,
                        desc->name);
@@ -902,6 +878,7 @@ int _lttng_event_unregister(struct lttng_event *event)
                lttng_uprobes_unregister(event);
                ret = 0;
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
        default:
                WARN_ON_ONCE(1);
        }
@@ -928,10 +905,6 @@ void _lttng_event_destroy(struct lttng_event *event)
                module_put(event->desc->owner);
                lttng_kretprobes_destroy_private(event);
                break;
-       case LTTNG_KERNEL_FUNCTION:
-               module_put(event->desc->owner);
-               lttng_ftrace_destroy_private(event);
-               break;
        case LTTNG_KERNEL_NOOP:
        case LTTNG_KERNEL_SYSCALL:
                break;
@@ -939,6 +912,7 @@ void _lttng_event_destroy(struct lttng_event *event)
                module_put(event->desc->owner);
                lttng_uprobes_destroy_private(event);
                break;
+       case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
        default:
                WARN_ON_ONCE(1);
        }
index 78b427a317d18972e9cea252b62154fc11b66b4d..6148fe12f0e1c90ce35a3c9d56cabe8f22c30761 100644 (file)
@@ -314,9 +314,6 @@ struct lttng_event {
                        struct lttng_krp *lttng_krp;
                        char *symbol_name;
                } kretprobe;
-               struct {
-                       char *symbol_name;
-               } ftrace;
                struct {
                        struct inode *inode;
                        struct list_head head;
@@ -978,32 +975,6 @@ int lttng_kretprobes_event_enable_state(struct lttng_event *event,
 }
 #endif
 
-#if defined(CONFIG_DYNAMIC_FTRACE) && !defined(LTTNG_FTRACE_MISSING_HEADER)
-int lttng_ftrace_register(const char *name,
-                         const char *symbol_name,
-                         struct lttng_event *event);
-void lttng_ftrace_unregister(struct lttng_event *event);
-void lttng_ftrace_destroy_private(struct lttng_event *event);
-#else
-static inline
-int lttng_ftrace_register(const char *name,
-                         const char *symbol_name,
-                         struct lttng_event *event)
-{
-       return -ENOSYS;
-}
-
-static inline
-void lttng_ftrace_unregister(struct lttng_event *event)
-{
-}
-
-static inline
-void lttng_ftrace_destroy_private(struct lttng_event *event)
-{
-}
-#endif
-
 int lttng_calibrate(struct lttng_kernel_calibrate *calibrate);
 
 extern const struct file_operations lttng_tracepoint_list_fops;
index b43dd497b5a5341ac6d614f5ae1f8c340884d553..c53718814d4646839bad46ac8812d0955cb81ec6 100644 (file)
@@ -234,14 +234,6 @@ ifneq ($(CONFIG_KRETPROBES),)
   obj-$(CONFIG_LTTNG) += lttng-kretprobes.o
 endif # CONFIG_KRETPROBES
 
-ifneq ($(CONFIG_DYNAMIC_FTRACE),)
-  ifeq ($(have_ftrace_header),yes)
-    obj-$(CONFIG_LTTNG) += lttng-ftrace.o
-  else
-    $(warning Files $(ftrace_dep) not found. Probe "ftrace" is disabled. Use full kernel source tree to enable it.)
-  endif
-endif # CONFIG_DYNAMIC_FTRACE
-
 ifneq ($(CONFIG_PREEMPTIRQ_EVENTS),)
   obj-$(CONFIG_LTTNG) += lttng-probe-preemptirq.o
 endif # CONFIG_PREEMPTIRQ_EVENTS
diff --git a/probes/lttng-ftrace.c b/probes/lttng-ftrace.c
deleted file mode 100644 (file)
index fe1bfd6..0000000
+++ /dev/null
@@ -1,236 +0,0 @@
-/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
- *
- * probes/lttng-ftrace.c
- *
- * LTTng function tracer integration module.
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- */
-
-/*
- * Ftrace function tracer does not seem to provide synchronization between probe
- * teardown and callback execution. Therefore, we make this module permanently
- * loaded (unloadable).
- *
- * TODO: Move to register_ftrace_function() (which is exported for
- * modules) for Linux >= 3.0. It is faster (only enables the selected
- * functions), and will stay there.
- */
-
-#include <linux/module.h>
-#include <linux/ftrace.h>
-#include <linux/slab.h>
-#include <lttng-events.h>
-#include <wrapper/ringbuffer/frontend_types.h>
-#include <wrapper/ftrace.h>
-#include <wrapper/vmalloc.h>
-#include <lttng-tracer.h>
-
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
-static
-void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-               struct trace_array *tr, struct ftrace_probe_ops *ops,
-               void *data)
-{
-       struct lttng_event *event = data;
-       struct lttng_probe_ctx lttng_probe_ctx = {
-               .event = event,
-               .interruptible = !irqs_disabled(),
-       };
-       struct lttng_channel *chan = event->chan;
-       struct lib_ring_buffer_ctx ctx;
-       struct {
-               unsigned long ip;
-               unsigned long parent_ip;
-       } payload;
-       int ret;
-
-       if (unlikely(!READ_ONCE(chan->session->active)))
-               return;
-       if (unlikely(!READ_ONCE(chan->enabled)))
-               return;
-       if (unlikely(!READ_ONCE(event->enabled)))
-               return;
-
-       lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
-                                sizeof(payload), lttng_alignof(payload), -1);
-       ret = chan->ops->event_reserve(&ctx, event->id);
-       if (ret < 0)
-               return;
-       payload.ip = ip;
-       payload.parent_ip = parent_ip;
-       lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
-       chan->ops->event_write(&ctx, &payload, sizeof(payload));
-       chan->ops->event_commit(&ctx);
-       return;
-}
-#else
-static
-void lttng_ftrace_handler(unsigned long ip, unsigned long parent_ip, void **data)
-{
-       struct lttng_event *event = *data;
-       struct lttng_probe_ctx lttng_probe_ctx = {
-               .event = event,
-               .interruptible = !irqs_disabled(),
-       };
-       struct lttng_channel *chan = event->chan;
-       struct lib_ring_buffer_ctx ctx;
-       struct {
-               unsigned long ip;
-               unsigned long parent_ip;
-       } payload;
-       int ret;
-
-       if (unlikely(!READ_ONCE(chan->session->active)))
-               return;
-       if (unlikely(!READ_ONCE(chan->enabled)))
-               return;
-       if (unlikely(!READ_ONCE(event->enabled)))
-               return;
-
-       lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx,
-                                sizeof(payload), lttng_alignof(payload), -1);
-       ret = chan->ops->event_reserve(&ctx, event->id);
-       if (ret < 0)
-               return;
-       payload.ip = ip;
-       payload.parent_ip = parent_ip;
-       lib_ring_buffer_align_ctx(&ctx, lttng_alignof(payload));
-       chan->ops->event_write(&ctx, &payload, sizeof(payload));
-       chan->ops->event_commit(&ctx);
-       return;
-}
-#endif
-
-/*
- * Create event description
- */
-static
-int lttng_create_ftrace_event(const char *name, struct lttng_event *event)
-{
-       struct lttng_event_field *fields;
-       struct lttng_event_desc *desc;
-       int ret;
-
-       desc = kzalloc(sizeof(*event->desc), GFP_KERNEL);
-       if (!desc)
-               return -ENOMEM;
-       desc->name = kstrdup(name, GFP_KERNEL);
-       if (!desc->name) {
-               ret = -ENOMEM;
-               goto error_str;
-       }
-       desc->nr_fields = 2;
-       desc->fields = fields =
-               kzalloc(2 * sizeof(struct lttng_event_field), GFP_KERNEL);
-       if (!desc->fields) {
-               ret = -ENOMEM;
-               goto error_fields;
-       }
-       fields[0].name = "ip";
-       fields[0].type.atype = atype_integer;
-       fields[0].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
-       fields[0].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
-       fields[0].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
-       fields[0].type.u.basic.integer.reverse_byte_order = 0;
-       fields[0].type.u.basic.integer.base = 16;
-       fields[0].type.u.basic.integer.encoding = lttng_encode_none;
-
-       fields[1].name = "parent_ip";
-       fields[1].type.atype = atype_integer;
-       fields[1].type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
-       fields[1].type.u.basic.integer.alignment = lttng_alignof(unsigned long) * CHAR_BIT;
-       fields[1].type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
-       fields[1].type.u.basic.integer.reverse_byte_order = 0;
-       fields[1].type.u.basic.integer.base = 16;
-       fields[1].type.u.basic.integer.encoding = lttng_encode_none;
-
-       desc->owner = THIS_MODULE;
-       event->desc = desc;
-
-       return 0;
-
-error_fields:
-       kfree(desc->name);
-error_str:
-       kfree(desc);
-       return ret;
-}
-
-static
-struct ftrace_probe_ops lttng_ftrace_ops = {
-       .func = lttng_ftrace_handler,
-};
-
-int lttng_ftrace_register(const char *name,
-                         const char *symbol_name,
-                         struct lttng_event *event)
-{
-       int ret;
-
-       ret = lttng_create_ftrace_event(name, event);
-       if (ret)
-               goto error;
-
-       event->u.ftrace.symbol_name = kstrdup(symbol_name, GFP_KERNEL);
-       if (!event->u.ftrace.symbol_name)
-               goto name_error;
-
-       /* Ensure the memory we just allocated don't trigger page faults */
-       wrapper_vmalloc_sync_all();
-
-       ret = wrapper_register_ftrace_function_probe(event->u.ftrace.symbol_name,
-                       &lttng_ftrace_ops, event);
-       if (ret < 0)
-               goto register_error;
-       return 0;
-
-register_error:
-       kfree(event->u.ftrace.symbol_name);
-name_error:
-       kfree(event->desc->name);
-       kfree(event->desc);
-error:
-       return ret;
-}
-EXPORT_SYMBOL_GPL(lttng_ftrace_register);
-
-void lttng_ftrace_unregister(struct lttng_event *event)
-{
-       wrapper_unregister_ftrace_function_probe(event->u.ftrace.symbol_name,
-                       &lttng_ftrace_ops, event);
-}
-EXPORT_SYMBOL_GPL(lttng_ftrace_unregister);
-
-void lttng_ftrace_destroy_private(struct lttng_event *event)
-{
-       kfree(event->u.ftrace.symbol_name);
-       kfree(event->desc->fields);
-       kfree(event->desc->name);
-       kfree(event->desc);
-}
-EXPORT_SYMBOL_GPL(lttng_ftrace_destroy_private);
-
-int lttng_ftrace_init(void)
-{
-       wrapper_vmalloc_sync_all();
-       return 0;
-}
-module_init(lttng_ftrace_init)
-
-/*
- * Ftrace takes care of waiting for a grace period (RCU sched) at probe
- * unregistration, and disables preemption around probe call.
- */
-void lttng_ftrace_exit(void)
-{
-}
-module_exit(lttng_ftrace_exit)
-
-MODULE_LICENSE("GPL and additional rights");
-MODULE_AUTHOR("Mathieu Desnoyers <mathieu.desnoyers@efficios.com>");
-MODULE_DESCRIPTION("LTTng ftrace probes");
-MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
-       __stringify(LTTNG_MODULES_MINOR_VERSION) "."
-       __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
-       LTTNG_MODULES_EXTRAVERSION);
diff --git a/wrapper/ftrace.h b/wrapper/ftrace.h
deleted file mode 100644 (file)
index eb4f788..0000000
+++ /dev/null
@@ -1,75 +0,0 @@
-/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
- *
- * wrapper/ftrace.h
- *
- * wrapper around vmalloc_sync_all. Using KALLSYMS to get its address when
- * available, else we need to have a kernel that exports this function to GPL
- * modules.
- *
- * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- */
-
-#ifndef _LTTNG_WRAPPER_FTRACE_H
-#define _LTTNG_WRAPPER_FTRACE_H
-
-#include <linux/ftrace.h>
-#include <linux/version.h>
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,12,0))
-#include <../kernel/trace/trace.h>
-#endif
-
-#ifdef CONFIG_KALLSYMS
-
-#include <linux/kallsyms.h>
-#include <wrapper/kallsyms.h>
-
-static inline
-int wrapper_register_ftrace_function_probe(char *glob,
-               struct ftrace_probe_ops *ops, void *data)
-{
-       int (*register_ftrace_function_probe_sym)(char *glob,
-                       struct ftrace_probe_ops *ops, void *data);
-
-       register_ftrace_function_probe_sym = (void *) kallsyms_lookup_funcptr("register_ftrace_function_probe");
-       if (register_ftrace_function_probe_sym) {
-               return register_ftrace_function_probe_sym(glob, ops, data);
-       } else {
-               printk_once(KERN_WARNING "LTTng: register_ftrace_function_probe symbol lookup failed.\n");
-               return -EINVAL;
-       }
-}
-
-static inline
-void wrapper_unregister_ftrace_function_probe(char *glob,
-               struct ftrace_probe_ops *ops, void *data)
-{
-       void (*unregister_ftrace_function_probe_sym)(char *glob,
-                       struct ftrace_probe_ops *ops, void *data);
-
-       unregister_ftrace_function_probe_sym = (void *) kallsyms_lookup_funcptr("unregister_ftrace_function_probe");
-       if (unregister_ftrace_function_probe_sym) {
-               unregister_ftrace_function_probe_sym(glob, ops, data);
-       } else {
-               printk_once(KERN_WARNING "LTTng: unregister_ftrace_function_probe symbol lookup failed.\n");
-               WARN_ON(1);
-       }
-}
-
-#else
-
-static inline
-int wrapper_register_ftrace_function_probe(char *glob,
-               struct ftrace_probe_ops *ops, void *data)
-{
-       return register_ftrace_function_probe(glob, ops, data);
-}
-
-static inline
-void wrapper_unregister_ftrace_function_probe(char *glob,
-               struct ftrace_probe_ops *ops, void *data)
-{
-       return unregister_ftrace_function_probe(glob, ops, data);
-}
-#endif
-
-#endif /* _LTTNG_WRAPPER_FTRACE_H */
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