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tracing/filters: Enable filtering a cpumask field by another cpumask

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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 <mhiramat@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Leonardo Bras <leobras@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Valentin Schneider 2023-07-07 18:21:48 +01:00 committed by Steven Rostedt (Google)
parent cfb58e278c
commit 39f7c41c90
2 changed files with 96 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/trace_events.h
View File

@ -808,6 +808,7 @@ enum {
FILTER_RDYN_STRING,
FILTER_PTR_STRING,
FILTER_TRACE_FN,
FILTER_CPUMASK,
FILTER_COMM,
FILTER_CPU,
FILTER_STACKTRACE,

97
kernel/trace/trace_events_filter.c
View File

@ -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];