From 39f7c41c908bc82947ce47cdd021520ff486c53f Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Fri, 7 Jul 2023 18:21:48 +0100 Subject: [PATCH] tracing/filters: Enable filtering a cpumask field by another cpumask The recently introduced ipi_send_cpumask trace event contains a cpumask field, but it currently cannot be used in filter expressions. Make event filtering aware of cpumask fields, and allow these to be filtered by a user-provided cpumask. The user-provided cpumask is to be given in cpulist format and wrapped as: "CPUS{$cpulist}". The use of curly braces instead of parentheses is to prevent predicate_parse() from parsing the contents of CPUS{...} as a full-fledged predicate subexpression. This enables e.g.: $ trace-cmd record -e 'ipi_send_cpumask' -f 'cpumask & CPUS{2,4,6,8-32}' Link: https://lkml.kernel.org/r/20230707172155.70873-3-vschneid@redhat.com Cc: Masami Hiramatsu Cc: Jonathan Corbet Cc: Juri Lelli Cc: Daniel Bristot de Oliveira Cc: Marcelo Tosatti Cc: Leonardo Bras Cc: Frederic Weisbecker Signed-off-by: Valentin Schneider Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_events.h | 1 + kernel/trace/trace_events_filter.c | 97 +++++++++++++++++++++++++++++++++++++- 2 files changed, 96 insertions(+), 2 deletions(-) diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h index c17623c..1600aeb8 100644 --- a/include/linux/trace_events.h +++ b/include/linux/trace_events.h @@ -808,6 +808,7 @@ enum { FILTER_RDYN_STRING, FILTER_PTR_STRING, FILTER_TRACE_FN, + FILTER_CPUMASK, FILTER_COMM, FILTER_CPU, FILTER_STACKTRACE, diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 91fc999..cb1863d 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -64,6 +64,7 @@ enum filter_pred_fn { FILTER_PRED_FN_PCHAR_USER, FILTER_PRED_FN_PCHAR, FILTER_PRED_FN_CPU, + FILTER_PRED_FN_CPUMASK, FILTER_PRED_FN_FUNCTION, FILTER_PRED_FN_, FILTER_PRED_TEST_VISITED, @@ -71,6 +72,7 @@ enum filter_pred_fn { struct filter_pred { struct regex *regex; + struct cpumask *mask; unsigned short *ops; struct ftrace_event_field *field; u64 val; @@ -94,6 +96,8 @@ struct filter_pred { C(TOO_MANY_OPEN, "Too many '('"), \ C(TOO_MANY_CLOSE, "Too few '('"), \ C(MISSING_QUOTE, "Missing matching quote"), \ + C(MISSING_BRACE_OPEN, "Missing '{'"), \ + C(MISSING_BRACE_CLOSE, "Missing '}'"), \ C(OPERAND_TOO_LONG, "Operand too long"), \ C(EXPECT_STRING, "Expecting string field"), \ C(EXPECT_DIGIT, "Expecting numeric field"), \ @@ -103,6 +107,7 @@ struct filter_pred { C(BAD_SUBSYS_FILTER, "Couldn't find or set field in one of a subsystem's events"), \ C(TOO_MANY_PREDS, "Too many terms in predicate expression"), \ C(INVALID_FILTER, "Meaningless filter expression"), \ + C(INVALID_CPULIST, "Invalid cpulist"), \ C(IP_FIELD_ONLY, "Only 'ip' field is supported for function trace"), \ C(INVALID_VALUE, "Invalid value (did you forget quotes)?"), \ C(NO_FUNCTION, "Function not found"), \ @@ -190,6 +195,7 @@ static void free_predicate(struct filter_pred *pred) { if (pred) { kfree(pred->regex); + kfree(pred->mask); kfree(pred); } } @@ -877,6 +883,26 @@ static int filter_pred_cpu(struct filter_pred *pred, void *event) } } +/* Filter predicate for cpumask field vs user-provided cpumask */ +static int filter_pred_cpumask(struct filter_pred *pred, void *event) +{ + u32 item = *(u32 *)(event + pred->offset); + int loc = item & 0xffff; + const struct cpumask *mask = (event + loc); + const struct cpumask *cmp = pred->mask; + + switch (pred->op) { + case OP_EQ: + return cpumask_equal(mask, cmp); + case OP_NE: + return !cpumask_equal(mask, cmp); + case OP_BAND: + return cpumask_intersects(mask, cmp); + default: + return 0; + } +} + /* Filter predicate for COMM. */ static int filter_pred_comm(struct filter_pred *pred, void *event) { @@ -1244,8 +1270,12 @@ static void filter_free_subsystem_filters(struct trace_subsystem_dir *dir, int filter_assign_type(const char *type) { - if (strstr(type, "__data_loc") && strstr(type, "char")) - return FILTER_DYN_STRING; + if (strstr(type, "__data_loc")) { + if (strstr(type, "char")) + return FILTER_DYN_STRING; + if (strstr(type, "cpumask_t")) + return FILTER_CPUMASK; + } if (strstr(type, "__rel_loc") && strstr(type, "char")) return FILTER_RDYN_STRING; @@ -1357,6 +1387,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event) return filter_pred_pchar(pred, event); case FILTER_PRED_FN_CPU: return filter_pred_cpu(pred, event); + case FILTER_PRED_FN_CPUMASK: + return filter_pred_cpumask(pred, event); case FILTER_PRED_FN_FUNCTION: return filter_pred_function(pred, event); case FILTER_PRED_TEST_VISITED: @@ -1568,6 +1600,67 @@ static int parse_pred(const char *str, void *data, strncpy(pred->regex->pattern, str + s, len); pred->regex->pattern[len] = 0; + } else if (!strncmp(str + i, "CPUS", 4)) { + unsigned int maskstart; + char *tmp; + + switch (field->filter_type) { + case FILTER_CPUMASK: + break; + default: + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i); + goto err_free; + } + + switch (op) { + case OP_EQ: + case OP_NE: + case OP_BAND: + break; + default: + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i); + goto err_free; + } + + /* Skip CPUS */ + i += 4; + if (str[i++] != '{') { + parse_error(pe, FILT_ERR_MISSING_BRACE_OPEN, pos + i); + goto err_free; + } + maskstart = i; + + /* Walk the cpulist until closing } */ + for (; str[i] && str[i] != '}'; i++); + if (str[i] != '}') { + parse_error(pe, FILT_ERR_MISSING_BRACE_CLOSE, pos + i); + goto err_free; + } + + if (maskstart == i) { + parse_error(pe, FILT_ERR_INVALID_CPULIST, pos + i); + goto err_free; + } + + /* Copy the cpulist between { and } */ + tmp = kmalloc((i - maskstart) + 1, GFP_KERNEL); + strscpy(tmp, str + maskstart, (i - maskstart) + 1); + + pred->mask = kzalloc(cpumask_size(), GFP_KERNEL); + if (!pred->mask) + goto err_mem; + + /* Now parse it */ + if (cpulist_parse(tmp, pred->mask)) { + parse_error(pe, FILT_ERR_INVALID_CPULIST, pos + i); + goto err_free; + } + + /* Move along */ + i++; + if (field->filter_type == FILTER_CPUMASK) + pred->fn_num = FILTER_PRED_FN_CPUMASK; + /* This is either a string, or an integer */ } else if (str[i] == '\'' || str[i] == '"') { char q = str[i]; -- 2.7.4