projects / lttng-modules.git / blame
| Commit | Line | Data |
|---|---|---|
| b7cdc182 | 1 | /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only) |
| 9f36eaed | 2 | * |
| 79150a49 JD |
3 | * lttng-context-preemptible.c |
| 4 | * | |
| 5 | * LTTng preemptible context. | |
| 6 | * | |
| 7 | * Copyright (C) 2009-2015 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
| 79150a49 JD |
8 | */ |
| 9 | ||
| 10 | #include <linux/module.h> | |
| 11 | #include <linux/slab.h> | |
| 12 | #include <linux/sched.h> | |
| 13 | #include <linux/irqflags.h> | |
| 2df37e95 | 14 | #include <lttng/events.h> |
| 24591303 | 15 | #include <ringbuffer/frontend_types.h> |
| 241ae9a8 | 16 | #include <wrapper/vmalloc.h> |
| 2df37e95 | 17 | #include <lttng/tracer.h> |
| 79150a49 JD |
18 | |
| 19 | /* | |
| 20 | * We nest twice in preempt disabling within LTTng: one nesting is done | |
| 21 | * by the instrumentation (tracepoint, kprobes, kretprobes, syscall | |
| 22 | * tracepoint), and the second is within the lib ring buffer | |
| 23 | * lib_ring_buffer_get_cpu(). | |
| 24 | */ | |
| 25 | #define LTTNG_PREEMPT_DISABLE_NESTING 2 | |
| 26 | ||
| 27 | static | |
| 28 | size_t preemptible_get_size(size_t offset) | |
| 29 | { | |
| 30 | size_t size = 0; | |
| 31 | ||
| 32 | size += lib_ring_buffer_align(offset, lttng_alignof(uint8_t)); | |
| 33 | size += sizeof(uint8_t); | |
| 34 | return size; | |
| 35 | } | |
| 36 | ||
| 37 | static | |
| 437d5aa5 | 38 | void preemptible_record(struct lttng_kernel_ctx_field *field, |
| 79150a49 JD |
39 | struct lib_ring_buffer_ctx *ctx, |
| 40 | struct lttng_channel *chan) | |
| 41 | { | |
| 42 | int pc = preempt_count(); | |
| 43 | uint8_t preemptible = 0; | |
| 44 | ||
| 45 | WARN_ON_ONCE(pc < LTTNG_PREEMPT_DISABLE_NESTING); | |
| 46 | if (pc == LTTNG_PREEMPT_DISABLE_NESTING) | |
| 47 | preemptible = 1; | |
| 48 | lib_ring_buffer_align_ctx(ctx, lttng_alignof(preemptible)); | |
| 49 | chan->ops->event_write(ctx, &preemptible, sizeof(preemptible)); | |
| 50 | } | |
| 51 | ||
| 52 | static | |
| 437d5aa5 | 53 | void preemptible_get_value(struct lttng_kernel_ctx_field *field, |
| 79150a49 JD |
54 | struct lttng_probe_ctx *lttng_probe_ctx, |
| 55 | union lttng_ctx_value *value) | |
| 56 | { | |
| 57 | int pc = preempt_count(); | |
| 58 | ||
| 59 | WARN_ON_ONCE(pc < LTTNG_PREEMPT_DISABLE_NESTING); | |
| 60 | if (pc == LTTNG_PREEMPT_DISABLE_NESTING) | |
| 61 | value->s64 = 1; | |
| 62 | else | |
| 63 | value->s64 = 0; | |
| 64 | } | |
| 65 | ||
| 087e3f1b MJ |
66 | static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field( |
| 67 | lttng_kernel_static_event_field("preemptible", | |
| 68 | lttng_kernel_static_type_integer_from_type(uint8_t, __BYTE_ORDER, 10), | |
| 69 | false, false, false), | |
| 70 | preemptible_get_size, | |
| 71 | NULL, | |
| 72 | preemptible_record, | |
| 73 | preemptible_get_value, | |
| 74 | NULL, NULL); | |
| 75 | ||
| 437d5aa5 | 76 | int lttng_add_preemptible_to_ctx(struct lttng_kernel_ctx **ctx) |
| 79150a49 | 77 | { |
| 087e3f1b | 78 | int ret; |
| 79150a49 | 79 | |
| 087e3f1b | 80 | if (lttng_kernel_find_context(*ctx, ctx_field->event_field->name)) |
| 79150a49 | 81 | return -EEXIST; |
| 087e3f1b | 82 | ret = lttng_kernel_context_append(ctx, ctx_field); |
| 263b6c88 | 83 | wrapper_vmalloc_sync_mappings(); |
| 087e3f1b | 84 | return ret; |
| 79150a49 JD |
85 | } |
| 86 | EXPORT_SYMBOL_GPL(lttng_add_preemptible_to_ctx); |