From 547ccf090a6a4ebaf88e7c46ad65bd126a9112b2 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Mon, 22 Nov 2021 18:30:12 +0900 Subject: [PATCH] tracing: Support __rel_loc relative dynamic data location attribute Add '__rel_loc' new dynamic data location attribute which encodes the data location from the next to the field itself. The '__data_loc' is used for encoding the dynamic data location on the trace event record. But '__data_loc' is not useful if the writer doesn't know the event header (e.g. user event), because it records the dynamic data offset from the entry of the record, not the field itself. This new '__rel_loc' attribute encodes the data location relatively from the next of the field. For example, when there is a record like below (the number in the parentheses is the size of fields) |header(N)|common(M)|fields(K)|__data_loc(4)|fields(L)|data(G)| In this case, '__data_loc' field will be __data_loc = (G << 16) | (N+M+K+4+L) If '__rel_loc' is used, this will be |header(N)|common(M)|fields(K)|__rel_loc(4)|fields(L)|data(G)| where __rel_loc = (G << 16) | (L) This case shows L bytes after the '__rel_loc' attribute field, if there is no fields after the __rel_loc field, L must be 0. This is relatively easy (and no need to consider the kernel header change) when the event data fields are composed by user who doesn't know header and common fields. Link: https://lkml.kernel.org/r/163757341258.510314.4214431827833229956.stgit@devnote2 Cc: Beau Belgrave Cc: Namhyung Kim Cc: Tom Zanussi Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- include/linux/trace_events.h | 1 + kernel/trace/trace.h | 1 + kernel/trace/trace_events_filter.c | 32 ++++++++++++++++++++++++++++-- kernel/trace/trace_events_hist.c | 21 ++++++++++++++++++-- kernel/trace/trace_events_inject.c | 11 ++++++++-- 5 files changed, 60 insertions(+), 6 deletions(-) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index 2d167ac3452c5..3900404aa0636 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -782,6 +782,7 @@ enum { FILTER_OTHER = 0, FILTER_STATIC_STRING, FILTER_DYN_STRING, + FILTER_RDYN_STRING, FILTER_PTR_STRING, FILTER_TRACE_FN, FILTER_COMM, diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index 38715aa6cfdfb..5db2bec8ca7e6 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -1465,6 +1465,7 @@ struct filter_pred { static inline bool is_string_field(struct ftrace_event_field *field) { return field->filter_type == FILTER_DYN_STRING || + field->filter_type == FILTER_RDYN_STRING || field->filter_type == FILTER_STATIC_STRING || field->filter_type == FILTER_PTR_STRING || field->filter_type == FILTER_COMM; diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index c9124038b140f..996920ed1812d 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -706,6 +706,29 @@ static int filter_pred_strloc(struct filter_pred *pred, void *event) return match; } +/* + * Filter predicate for relative dynamic sized arrays of characters. + * These are implemented through a list of strings at the end + * of the entry as same as dynamic string. + * The difference is that the relative one records the location offset + * from the field itself, not the event entry. + */ +static int filter_pred_strrelloc(struct filter_pred *pred, void *event) +{ + u32 *item = (u32 *)(event + pred->offset); + u32 str_item = *item; + int str_loc = str_item & 0xffff; + int str_len = str_item >> 16; + char *addr = (char *)(&item[1]) + str_loc; + int cmp, match; + + cmp = pred->regex.match(addr, &pred->regex, str_len); + + match = cmp ^ pred->not; + + return match; +} + /* Filter predicate for CPUs. */ static int filter_pred_cpu(struct filter_pred *pred, void *event) { @@ -756,7 +779,7 @@ static int filter_pred_none(struct filter_pred *pred, void *event) * * Note: * - @str might not be NULL-terminated if it's of type DYN_STRING - * or STATIC_STRING, unless @len is zero. + * RDYN_STRING, or STATIC_STRING, unless @len is zero. */ static int regex_match_full(char *str, struct regex *r, int len) @@ -1083,6 +1106,9 @@ int filter_assign_type(const char *type) if (strstr(type, "__data_loc") && strstr(type, "char")) return FILTER_DYN_STRING; + if (strstr(type, "__rel_loc") && strstr(type, "char")) + return FILTER_RDYN_STRING; + if (strchr(type, '[') && strstr(type, "char")) return FILTER_STATIC_STRING; @@ -1318,8 +1344,10 @@ static int parse_pred(const char *str, void *data, pred->fn = filter_pred_string; pred->regex.field_len = field->size; - } else if (field->filter_type == FILTER_DYN_STRING) + } else if (field->filter_type == FILTER_DYN_STRING) { pred->fn = filter_pred_strloc; + } else if (field->filter_type == FILTER_RDYN_STRING) + pred->fn = filter_pred_strrelloc; else pred->fn = filter_pred_pchar; /* go past the last quote */ diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 319f9c8ca7e7d..9b8da439149ca 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -217,6 +217,20 @@ static u64 hist_field_dynstring(struct hist_field *hist_field, return (u64)(unsigned long)addr; } +static u64 hist_field_reldynstring(struct hist_field *hist_field, + struct tracing_map_elt *elt, + struct trace_buffer *buffer, + struct ring_buffer_event *rbe, + void *event) +{ + u32 *item = event + hist_field->field->offset; + u32 str_item = *item; + int str_loc = str_item & 0xffff; + char *addr = (char *)&item[1] + str_loc; + + return (u64)(unsigned long)addr; +} + static u64 hist_field_pstring(struct hist_field *hist_field, struct tracing_map_elt *elt, struct trace_buffer *buffer, @@ -1956,8 +1970,10 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data, if (field->filter_type == FILTER_STATIC_STRING) { hist_field->fn = hist_field_string; hist_field->size = field->size; - } else if (field->filter_type == FILTER_DYN_STRING) + } else if (field->filter_type == FILTER_DYN_STRING) { hist_field->fn = hist_field_dynstring; + } else if (field->filter_type == FILTER_RDYN_STRING) + hist_field->fn = hist_field_reldynstring; else hist_field->fn = hist_field_pstring; } else { @@ -4961,7 +4977,8 @@ static inline void add_to_key(char *compound_key, void *key, struct ftrace_event_field *field; field = key_field->field; - if (field->filter_type == FILTER_DYN_STRING) + if (field->filter_type == FILTER_DYN_STRING || + field->filter_type == FILTER_RDYN_STRING) size = *(u32 *)(rec + field->offset) >> 16; else if (field->filter_type == FILTER_STATIC_STRING) size = field->size; diff --git a/kernel/trace/trace_events_inject.c b/kernel/trace/trace_events_inject.c index c188045c5f976..d6b4935a78c08 100644 --- a/kernel/trace/trace_events_inject.c +++ b/kernel/trace/trace_events_inject.c @@ -168,10 +168,14 @@ static void *trace_alloc_entry(struct trace_event_call *call, int *size) continue; if (field->filter_type == FILTER_STATIC_STRING) continue; - if (field->filter_type == FILTER_DYN_STRING) { + if (field->filter_type == FILTER_DYN_STRING || + field->filter_type == FILTER_RDYN_STRING) { u32 *str_item; int str_loc = entry_size & 0xffff; + if (field->filter_type == FILTER_RDYN_STRING) + str_loc -= field->offset + field->size; + str_item = (u32 *)(entry + field->offset); *str_item = str_loc; /* string length is 0. */ } else { @@ -214,7 +218,8 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry) if (field->filter_type == FILTER_STATIC_STRING) { strlcpy(entry + field->offset, addr, field->size); - } else if (field->filter_type == FILTER_DYN_STRING) { + } else if (field->filter_type == FILTER_DYN_STRING || + field->filter_type == FILTER_RDYN_STRING) { int str_len = strlen(addr) + 1; int str_loc = entry_size & 0xffff; u32 *str_item; @@ -229,6 +234,8 @@ static int parse_entry(char *str, struct trace_event_call *call, void **pentry) strlcpy(entry + (entry_size - str_len), addr, str_len); str_item = (u32 *)(entry + field->offset); + if (field->filter_type == FILTER_RDYN_STRING) + str_loc -= field->offset + field->size; *str_item = (str_len << 16) | str_loc; } else { char **paddr; -- 2.39.5