+++ /dev/null
-/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
- *
- * lttng-context-callstack.c
- *
- * LTTng callstack event context.
- *
- * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2014 Francis Giraldeau <francis.giraldeau@gmail.com>
- *
- * The callstack context can be added to any kernel event. It records
- * either the kernel or the userspace callstack, up to a max depth. The
- * context is a CTF sequence, such that it uses only the space required
- * for the number of callstack entries.
- *
- * It allocates callstack buffers per-CPU up to 4 interrupt nesting.
- * This nesting limit is the same as defined in the ring buffer. It
- * therefore uses a fixed amount of memory, proportional to the number
- * of CPUs:
- *
- * size = cpus * nest * depth * sizeof(unsigned long)
- *
- * Which is 4096 bytes per CPU on 64-bit host and a depth of 128.
- * The allocation is done at the initialization to avoid memory
- * allocation overhead while tracing, using a shallow stack.
- *
- * The kernel callstack is recovered using save_stack_trace(), and the
- * userspace callstack uses save_stack_trace_user(). They rely on frame
- * pointers. These are usually available for the kernel, but the
- * compiler option -fomit-frame-pointer frequently used in popular Linux
- * distributions may cause the userspace callstack to be unreliable, and
- * is a known limitation of this approach. If frame pointers are not
- * available, it produces no error, but the callstack will be empty. We
- * still provide the feature, because it works well for runtime
- * environments having frame pointers. In the future, unwind support
- * and/or last branch record may provide a solution to this problem.
- *
- * The symbol name resolution is left to the trace reader.
- */
-
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/sched.h>
-#include <linux/utsname.h>
-#include <linux/stacktrace.h>
-#include <linux/spinlock.h>
-#include "lttng-events.h"
-#include "wrapper/ringbuffer/backend.h"
-#include "wrapper/ringbuffer/frontend.h"
-#include "wrapper/vmalloc.h"
-#include "lttng-tracer.h"
-
-#include "lttng-context-callstack-legacy-impl.h"
-
-static
-void field_data_free(struct field_data *fdata)
-{
- if (!fdata)
- return;
- free_percpu(fdata->cs_percpu);
- kfree(fdata);
-}
-
-static
-struct field_data __percpu *field_data_create(enum lttng_cs_ctx_modes mode)
-{
- struct lttng_cs __percpu *cs_set;
- struct field_data *fdata;
-
- fdata = kzalloc(sizeof(*fdata), GFP_KERNEL);
- if (!fdata)
- return NULL;
- cs_set = alloc_percpu(struct lttng_cs);
- if (!cs_set)
- goto error_alloc;
- lttng_cs_set_init(cs_set);
- fdata->cs_percpu = cs_set;
- fdata->mode = mode;
- return fdata;
-
-error_alloc:
- field_data_free(fdata);
- return NULL;
-}
-
-static
-void lttng_callstack_destroy(struct lttng_ctx_field *field)
-{
- struct field_data *fdata = field->priv;
-
- field_data_free(fdata);
-}
-
-static
-int __lttng_add_callstack_generic(struct lttng_ctx **ctx,
- enum lttng_cs_ctx_modes mode)
-{
- const char *ctx_name = lttng_cs_ctx_mode_name(mode);
- struct lttng_ctx_field *field;
- struct field_data *fdata;
- int ret;
-
- ret = init_type(mode);
- if (ret)
- return ret;
- field = lttng_append_context(ctx);
- if (!field)
- return -ENOMEM;
- if (lttng_find_context(*ctx, ctx_name)) {
- ret = -EEXIST;
- goto error_find;
- }
- fdata = field_data_create(mode);
- if (!fdata) {
- ret = -ENOMEM;
- goto error_create;
- }
-
- field->event_field.name = ctx_name;
- field->event_field.type.atype = atype_sequence;
- field->event_field.type.u.sequence.elem_type.atype = atype_integer;
- field->event_field.type.u.sequence.elem_type.u.basic.integer.size = sizeof(unsigned long) * CHAR_BIT;
- field->event_field.type.u.sequence.elem_type.u.basic.integer.alignment = lttng_alignof(long) * CHAR_BIT;
- field->event_field.type.u.sequence.elem_type.u.basic.integer.signedness = lttng_is_signed_type(unsigned long);
- field->event_field.type.u.sequence.elem_type.u.basic.integer.reverse_byte_order = 0;
- field->event_field.type.u.sequence.elem_type.u.basic.integer.base = 16;
- field->event_field.type.u.sequence.elem_type.u.basic.integer.encoding = lttng_encode_none;
-
- field->event_field.type.u.sequence.length_type.atype = atype_integer;
- field->event_field.type.u.sequence.length_type.u.basic.integer.size = sizeof(unsigned int) * CHAR_BIT;
- field->event_field.type.u.sequence.length_type.u.basic.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT;
- field->event_field.type.u.sequence.length_type.u.basic.integer.signedness = lttng_is_signed_type(unsigned int);
- field->event_field.type.u.sequence.length_type.u.basic.integer.reverse_byte_order = 0;
- field->event_field.type.u.sequence.length_type.u.basic.integer.base = 10;
- field->event_field.type.u.sequence.length_type.u.basic.integer.encoding = lttng_encode_none;
-
- field->get_size_arg = lttng_callstack_get_size;
- field->record = lttng_callstack_record;
- field->priv = fdata;
- field->destroy = lttng_callstack_destroy;
- wrapper_vmalloc_sync_all();
- return 0;
-
-error_create:
- field_data_free(fdata);
-error_find:
- lttng_remove_context_field(ctx, field);
- return ret;
-}
-
-/**
- * lttng_add_callstack_to_ctx - add callstack event context
- *
- * @ctx: the lttng_ctx pointer to initialize
- * @type: the context type
- *
- * Supported callstack type supported:
- * LTTNG_KERNEL_CONTEXT_CALLSTACK_KERNEL
- * Records the callstack of the kernel
- * LTTNG_KERNEL_CONTEXT_CALLSTACK_USER
- * Records the callstack of the userspace program (from the kernel)
- *
- * Return 0 for success, or error code.
- */
-int lttng_add_callstack_to_ctx(struct lttng_ctx **ctx, int type)
-{
- switch (type) {
- case LTTNG_KERNEL_CONTEXT_CALLSTACK_KERNEL:
- return __lttng_add_callstack_generic(ctx, CALLSTACK_KERNEL);
-#ifdef CONFIG_X86
- case LTTNG_KERNEL_CONTEXT_CALLSTACK_USER:
- return __lttng_add_callstack_generic(ctx, CALLSTACK_USER);
-#endif
- default:
- return -EINVAL;
- }
-}
-EXPORT_SYMBOL_GPL(lttng_add_callstack_to_ctx);
projects / lttng-modules.git / blobdiff