X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lttng-context-callstack.c;h=1e791f9c5b24eaa62bad40fe079d5432be5c095c;hb=263b6c88138c3354d63dba3c70a965de94becd22;hp=3b7859eb8542b8c6bc073288f2380cf3b29e37fb;hpb=64cc198b453a1fd05fb6f23bda08282ed0902c1c;p=lttng-modules.git diff --git a/lttng-context-callstack.c b/lttng-context-callstack.c index 3b7859eb..1e791f9c 100644 --- a/lttng-context-callstack.c +++ b/lttng-context-callstack.c @@ -1,4 +1,5 @@ -/* +/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) + * * lttng-context-callstack.c * * LTTng callstack event context. @@ -6,45 +7,32 @@ * Copyright (C) 2014 Mathieu Desnoyers * Copyright (C) 2014 Francis Giraldeau * - * This library is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public - * License as published by the Free Software Foundation; only - * version 2.1 of the License. - * - * This library is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - * Lesser General Public License for more details. - * - * You should have received a copy of the GNU Lesser General Public - * License along with this library; if not, write to the Free Software - * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - * - * 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. + * 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: + * 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 about 800 bytes per-CPUs on 64-bit host and a depth of 25. The - * allocation is done at the initialization to avoid memory allocation - * overhead while tracing, using a shallow stack. + * 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. + * 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. */ @@ -60,154 +48,13 @@ #include "wrapper/ringbuffer/frontend.h" #include "wrapper/vmalloc.h" #include "lttng-tracer.h" +#include "lttng-endian.h" -#define MAX_ENTRIES 25 - -struct lttng_cs_nesting { - struct stack_trace stack_trace; - unsigned long entries[MAX_ENTRIES]; -}; - -struct lttng_cs { - struct lttng_cs_nesting level[RING_BUFFER_MAX_NESTING]; -}; - -struct field_data { - struct lttng_cs __percpu *cs_percpu; - int mode; -}; - -struct lttng_cs_type { - const char *name; - const char *save_func_name; - void (*save_func)(struct stack_trace *trace); -}; - -enum lttng_cs_ctx_modes { - CALLSTACK_KERNEL = 0, - CALLSTACK_USER = 1, -}; - -static struct lttng_cs_type cs_types[] = { - { - .name = "callstack_kernel", - .save_func_name = "save_stack_trace", - .save_func = NULL, - }, - { - .name = "callstack_user", - .save_func_name = "save_stack_trace_user", - .save_func = NULL, - }, -}; - -static -int init_type(int mode) -{ - unsigned long func; - - if (cs_types[mode].save_func) - return 0; - func = kallsyms_lookup_funcptr(cs_types[mode].save_func_name); - if (!func) { - printk(KERN_WARNING "LTTng: symbol lookup failed: %s\n", - cs_types[mode].save_func_name); - return -EINVAL; - } - cs_types[mode].save_func = (void *) func; - return 0; -} - -static -struct stack_trace *stack_trace_context(struct lttng_ctx_field *field, - struct lib_ring_buffer_ctx *ctx) -{ - int nesting; - struct lttng_cs *cs; - struct field_data *fdata = field->priv; - - /* - * get_cpu() is not required, preemption is already - * disabled while event is written. - * - * max nesting is checked in lib_ring_buffer_get_cpu(). - * Check it again as a safety net. - */ - cs = per_cpu_ptr(fdata->cs_percpu, ctx->cpu); - nesting = per_cpu(lib_ring_buffer_nesting, ctx->cpu) - 1; - if (nesting >= RING_BUFFER_MAX_NESTING) { - return NULL; - } - return &cs->level[nesting].stack_trace; -} - -/* - * In order to reserve the correct size, the callstack is computed. The - * resulting callstack is saved to be accessed in the record step. - */ -static -size_t lttng_callstack_get_size(size_t offset, struct lttng_ctx_field *field, - struct lib_ring_buffer_ctx *ctx, - struct lttng_channel *chan) -{ - size_t size = 0; - struct stack_trace *trace; - struct field_data *fdata = field->priv; - - /* do not write data if no space is available */ - trace = stack_trace_context(field, ctx); - if (!trace) - return 0; - - /* reset stack trace, no need to clear memory */ - trace->nr_entries = 0; - - /* do the real work and reserve space */ - cs_types[fdata->mode].save_func(trace); - /* - * Remove final ULONG_MAX delimiter. If we cannot find it, add - * our own marker to show that the stack is incomplete. This is - * more compact for a trace. - */ - if (trace->nr_entries > 0 - && trace->entries[trace->nr_entries - 1] == ULONG_MAX) { - trace->nr_entries--; - } - size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int)); - size += sizeof(unsigned int); - size += lib_ring_buffer_align(offset, lttng_alignof(unsigned long)); - size += sizeof(unsigned long) * trace->nr_entries; - /* Add our own ULONG_MAX delimiter to show incomplete stack. */ - if (trace->nr_entries == trace->max_entries) - size += sizeof(unsigned long); - return size; -} - -static -void lttng_callstack_record(struct lttng_ctx_field *field, - struct lib_ring_buffer_ctx *ctx, - struct lttng_channel *chan) -{ - struct stack_trace *trace = stack_trace_context(field, ctx); - unsigned int nr_seq_entries; - - if (!trace) - return; - lib_ring_buffer_align_ctx(ctx, lttng_alignof(unsigned int)); - nr_seq_entries = trace->nr_entries; - if (trace->nr_entries == trace->max_entries) - nr_seq_entries++; - chan->ops->event_write(ctx, &nr_seq_entries, sizeof(unsigned int)); - lib_ring_buffer_align_ctx(ctx, lttng_alignof(unsigned long)); - chan->ops->event_write(ctx, trace->entries, - sizeof(unsigned long) * trace->nr_entries); - /* Add our own ULONG_MAX delimiter to show incomplete stack. */ - if (trace->nr_entries == trace->max_entries) { - unsigned long delim = ULONG_MAX; - - chan->ops->event_write(ctx, &delim, sizeof(unsigned long)); - } -} +#ifdef CONFIG_ARCH_STACKWALK +#include "lttng-context-callstack-stackwalk-impl.h" +#else +#include "lttng-context-callstack-legacy-impl.h" +#endif static void field_data_free(struct field_data *fdata) @@ -219,9 +66,8 @@ void field_data_free(struct field_data *fdata) } static -struct field_data __percpu *field_data_create(int type) +struct field_data __percpu *field_data_create(enum lttng_cs_ctx_modes mode) { - int cpu, i; struct lttng_cs __percpu *cs_set; struct field_data *fdata; @@ -231,21 +77,9 @@ struct field_data __percpu *field_data_create(int type) cs_set = alloc_percpu(struct lttng_cs); if (!cs_set) goto error_alloc; - + lttng_cs_set_init(cs_set); fdata->cs_percpu = cs_set; - for_each_possible_cpu(cpu) { - struct lttng_cs *cs; - - cs = per_cpu_ptr(cs_set, cpu); - for (i = 0; i < RING_BUFFER_MAX_NESTING; i++) { - struct lttng_cs_nesting *level; - - level = &cs->level[i]; - level->stack_trace.entries = level->entries; - level->stack_trace.max_entries = MAX_ENTRIES; - } - } - fdata->mode = type; + fdata->mode = mode; return fdata; error_alloc: @@ -254,27 +88,38 @@ error_alloc: } static -void lttng_callstack_destroy(struct lttng_ctx_field *field) +void lttng_callstack_sequence_destroy(struct lttng_ctx_field *field) { struct field_data *fdata = field->priv; field_data_free(fdata); } +static const struct lttng_type sequence_elem_type = + __type_integer(unsigned long, 0, 0, -1, __BYTE_ORDER, 16, none); + static -int __lttng_add_callstack_generic(struct lttng_ctx **ctx, int mode) +int __lttng_add_callstack_generic(struct lttng_ctx **ctx, + enum lttng_cs_ctx_modes mode) { - const char *ctx_name = cs_types[mode].name; - struct lttng_ctx_field *field; + const char *ctx_name = lttng_cs_ctx_mode_name(mode); + const char *ctx_length_name = lttng_cs_ctx_mode_length_name(mode); + struct lttng_ctx_field *length_field, *sequence_field; + struct lttng_event_field *field; struct field_data *fdata; int ret; ret = init_type(mode); if (ret) return ret; - field = lttng_append_context(ctx); - if (!field) + length_field = lttng_append_context(ctx); + if (!length_field) + return -ENOMEM; + sequence_field = lttng_append_context(ctx); + if (!sequence_field) { + lttng_remove_context_field(ctx, length_field); return -ENOMEM; + } if (lttng_find_context(*ctx, ctx_name)) { ret = -EEXIST; goto error_find; @@ -285,35 +130,36 @@ int __lttng_add_callstack_generic(struct lttng_ctx **ctx, int mode) 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(); + field = &length_field->event_field; + field->name = ctx_length_name; + field->type.atype = atype_integer; + field->type.u.integer.size = sizeof(unsigned int) * CHAR_BIT; + field->type.u.integer.alignment = lttng_alignof(unsigned int) * CHAR_BIT; + field->type.u.integer.signedness = lttng_is_signed_type(unsigned int); + field->type.u.integer.reverse_byte_order = 0; + field->type.u.integer.base = 10; + field->type.u.integer.encoding = lttng_encode_none; + length_field->get_size_arg = lttng_callstack_length_get_size; + length_field->record = lttng_callstack_length_record; + + field = &sequence_field->event_field; + field->name = ctx_name; + field->type.atype = atype_sequence_nestable; + field->type.u.sequence_nestable.elem_type = &sequence_elem_type; + field->type.u.sequence_nestable.alignment = 0; + sequence_field->get_size_arg = lttng_callstack_sequence_get_size; + sequence_field->record = lttng_callstack_sequence_record; + sequence_field->priv = fdata; + sequence_field->destroy = lttng_callstack_sequence_destroy; + + wrapper_vmalloc_sync_mappings(); return 0; error_create: field_data_free(fdata); error_find: - lttng_remove_context_field(ctx, field); + lttng_remove_context_field(ctx, sequence_field); + lttng_remove_context_field(ctx, length_field); return ret; } @@ -336,14 +182,12 @@ 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); - -MODULE_LICENSE("GPL and additional rights"); -MODULE_AUTHOR("Francis Giraldeau"); -MODULE_DESCRIPTION("Linux Trace Toolkit Callstack Support");