+++ /dev/null
-/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
- *
- * lttng-context-callstack-stackwalk-impl.h
- *
- * LTTng callstack event context, stackwalk implementation. Targets
- * kernels and architectures using the stacktrace common infrastructure
- * introduced in the upstream Linux kernel by commit 214d8ca6ee
- * "stacktrace: Provide common infrastructure" (merged in Linux 5.2,
- * then gradually introduced within architectures).
- *
- * Copyright (C) 2014-2019 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2014 Francis Giraldeau <francis.giraldeau@gmail.com>
- */
-
-#define MAX_ENTRIES 128
-
-enum lttng_cs_ctx_modes {
- CALLSTACK_KERNEL = 0,
- CALLSTACK_USER = 1,
- NR_CALLSTACK_MODES,
-};
-
-struct lttng_stack_trace {
- unsigned long entries[MAX_ENTRIES];
- unsigned int nr_entries;
-};
-
-struct lttng_cs {
- struct lttng_stack_trace stack_trace[RING_BUFFER_MAX_NESTING];
-};
-
-struct field_data {
- struct lttng_cs __percpu *cs_percpu;
- enum lttng_cs_ctx_modes mode;
-};
-
-static
-unsigned int (*save_func_kernel)(unsigned long *store, unsigned int size,
- unsigned int skipnr);
-static
-unsigned int (*save_func_user)(unsigned long *store, unsigned int size);
-
-static
-const char *lttng_cs_ctx_mode_name(enum lttng_cs_ctx_modes mode)
-{
- switch (mode) {
- case CALLSTACK_KERNEL:
- return "callstack_kernel";
- case CALLSTACK_USER:
- return "callstack_user";
- default:
- return NULL;
- }
-}
-
-static
-const char *lttng_cs_ctx_mode_length_name(enum lttng_cs_ctx_modes mode)
-{
- switch (mode) {
- case CALLSTACK_KERNEL:
- return "_callstack_kernel_length";
- case CALLSTACK_USER:
- return "_callstack_user_length";
- default:
- return NULL;
- }
-}
-
-static
-int init_type_callstack_kernel(void)
-{
- unsigned long func;
- const char *func_name = "stack_trace_save";
-
- if (save_func_kernel)
- return 0;
- func = kallsyms_lookup_funcptr(func_name);
- if (!func) {
- printk(KERN_WARNING "LTTng: symbol lookup failed: %s\n",
- func_name);
- return -EINVAL;
- }
- save_func_kernel = (void *) func;
- return 0;
-}
-
-static
-int init_type_callstack_user(void)
-{
- unsigned long func;
- const char *func_name = "stack_trace_save_user";
-
- if (save_func_user)
- return 0;
- func = kallsyms_lookup_funcptr(func_name);
- if (!func) {
- printk(KERN_WARNING "LTTng: symbol lookup failed: %s\n",
- func_name);
- return -EINVAL;
- }
- save_func_user = (void *) func;
- return 0;
-}
-
-static
-int init_type(enum lttng_cs_ctx_modes mode)
-{
- switch (mode) {
- case CALLSTACK_KERNEL:
- return init_type_callstack_kernel();
- case CALLSTACK_USER:
- return init_type_callstack_user();
- default:
- return -EINVAL;
- }
-}
-
-static
-void lttng_cs_set_init(struct lttng_cs __percpu *cs_set)
-{
-}
-
-/* Keep track of nesting inside userspace callstack context code */
-DEFINE_PER_CPU(int, callstack_user_nesting);
-
-static
-struct lttng_stack_trace *stack_trace_context(struct lttng_ctx_field *field,
- struct lib_ring_buffer_ctx *ctx)
-{
- int buffer_nesting, cs_user_nesting;
- struct lttng_cs *cs;
- struct field_data *fdata = field->priv;
-
- /*
- * Do not gather the userspace callstack context when the event was
- * triggered by the userspace callstack context saving mechanism.
- */
- cs_user_nesting = per_cpu(callstack_user_nesting, ctx->cpu);
-
- if (fdata->mode == CALLSTACK_USER && cs_user_nesting >= 1)
- return NULL;
-
- /*
- * 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);
- buffer_nesting = per_cpu(lib_ring_buffer_nesting, ctx->cpu) - 1;
- if (buffer_nesting >= RING_BUFFER_MAX_NESTING)
- return NULL;
-
- return &cs->stack_trace[buffer_nesting];
-}
-
-static
-size_t lttng_callstack_length_get_size(size_t offset, struct lttng_ctx_field *field,
- struct lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- size_t orig_offset = offset;
-
- offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
- offset += sizeof(unsigned int);
- return offset - orig_offset;
-}
-
-/*
- * 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_sequence_get_size(size_t offset, struct lttng_ctx_field *field,
- struct lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- struct lttng_stack_trace *trace;
- struct field_data *fdata = field->priv;
- size_t orig_offset = offset;
-
- /* do not write data if no space is available */
- trace = stack_trace_context(field, ctx);
- if (unlikely(!trace)) {
- offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
- return offset - orig_offset;
- }
-
- /* reset stack trace, no need to clear memory */
- trace->nr_entries = 0;
-
- switch (fdata->mode) {
- case CALLSTACK_KERNEL:
- /* do the real work and reserve space */
- trace->nr_entries = save_func_kernel(trace->entries,
- MAX_ENTRIES, 0);
- break;
- case CALLSTACK_USER:
- ++per_cpu(callstack_user_nesting, ctx->cpu);
- /* do the real work and reserve space */
- trace->nr_entries = save_func_user(trace->entries,
- MAX_ENTRIES);
- per_cpu(callstack_user_nesting, ctx->cpu)--;
- break;
- default:
- WARN_ON_ONCE(1);
- }
-
- /*
- * If the array is filled, add our own marker to show that the
- * stack is incomplete.
- */
- offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
- offset += sizeof(unsigned long) * trace->nr_entries;
- /* Add our own ULONG_MAX delimiter to show incomplete stack. */
- if (trace->nr_entries == MAX_ENTRIES)
- offset += sizeof(unsigned long);
- return offset - orig_offset;
-}
-
-static
-void lttng_callstack_length_record(struct lttng_ctx_field *field,
- struct lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- struct lttng_stack_trace *trace = stack_trace_context(field, ctx);
- unsigned int nr_seq_entries;
-
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(unsigned int));
- if (unlikely(!trace)) {
- nr_seq_entries = 0;
- } else {
- nr_seq_entries = trace->nr_entries;
- if (trace->nr_entries == MAX_ENTRIES)
- nr_seq_entries++;
- }
- chan->ops->event_write(ctx, &nr_seq_entries, sizeof(unsigned int));
-}
-
-static
-void lttng_callstack_sequence_record(struct lttng_ctx_field *field,
- struct lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- struct lttng_stack_trace *trace = stack_trace_context(field, ctx);
- unsigned int nr_seq_entries;
-
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(unsigned long));
- if (unlikely(!trace)) {
- return;
- }
- nr_seq_entries = trace->nr_entries;
- if (trace->nr_entries == MAX_ENTRIES)
- nr_seq_entries++;
- 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 == MAX_ENTRIES) {
- unsigned long delim = ULONG_MAX;
-
- chan->ops->event_write(ctx, &delim, sizeof(unsigned long));
- }
-}
projects / lttng-modules.git / blobdiff