tracing/synthetic: Use union instead of casts
The current code uses a lot of casts to access the fields member in struct
synth_trace_events with different sizes. This makes the code hard to
read, and had already introduced an endianness bug. Use a union and struct
instead.
Link: https://lkml.kernel.org/r/20230816154928.4171614-2-svens@linux.ibm.com
Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 00cf3d672a
("tracing: Allow synthetic events to pass around stacktraces")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
parent
5450be6bef
commit
ddeea494a1
@ -59,6 +59,17 @@ int trace_raw_output_prep(struct trace_iterator *iter,
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extern __printf(2, 3)
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extern __printf(2, 3)
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void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...);
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void trace_event_printf(struct trace_iterator *iter, const char *fmt, ...);
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/* Used to find the offset and length of dynamic fields in trace events */
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struct trace_dynamic_info {
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#ifdef CONFIG_CPU_BIG_ENDIAN
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u16 offset;
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u16 len;
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#else
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u16 len;
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u16 offset;
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#endif
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};
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/*
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/*
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* The trace entry - the most basic unit of tracing. This is what
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* The trace entry - the most basic unit of tracing. This is what
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* is printed in the end as a single line in the trace output, such as:
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* is printed in the end as a single line in the trace output, such as:
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@ -1295,6 +1295,14 @@ static inline void trace_branch_disable(void)
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/* set ring buffers to default size if not already done so */
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/* set ring buffers to default size if not already done so */
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int tracing_update_buffers(void);
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int tracing_update_buffers(void);
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union trace_synth_field {
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u8 as_u8;
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u16 as_u16;
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u32 as_u32;
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u64 as_u64;
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struct trace_dynamic_info as_dynamic;
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};
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struct ftrace_event_field {
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struct ftrace_event_field {
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struct list_head link;
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struct list_head link;
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const char *name;
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const char *name;
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@ -127,7 +127,7 @@ static bool synth_event_match(const char *system, const char *event,
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struct synth_trace_event {
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struct synth_trace_event {
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struct trace_entry ent;
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struct trace_entry ent;
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u64 fields[];
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union trace_synth_field fields[];
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};
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};
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static int synth_event_define_fields(struct trace_event_call *call)
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static int synth_event_define_fields(struct trace_event_call *call)
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@ -321,19 +321,19 @@ static const char *synth_field_fmt(char *type)
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static void print_synth_event_num_val(struct trace_seq *s,
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static void print_synth_event_num_val(struct trace_seq *s,
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char *print_fmt, char *name,
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char *print_fmt, char *name,
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int size, u64 val, char *space)
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int size, union trace_synth_field *val, char *space)
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{
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{
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switch (size) {
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switch (size) {
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case 1:
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case 1:
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trace_seq_printf(s, print_fmt, name, (u8)val, space);
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trace_seq_printf(s, print_fmt, name, val->as_u8, space);
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break;
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break;
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case 2:
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case 2:
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trace_seq_printf(s, print_fmt, name, (u16)val, space);
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trace_seq_printf(s, print_fmt, name, val->as_u16, space);
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break;
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break;
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case 4:
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case 4:
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trace_seq_printf(s, print_fmt, name, (u32)val, space);
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trace_seq_printf(s, print_fmt, name, val->as_u32, space);
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break;
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break;
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default:
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default:
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@ -374,36 +374,26 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
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/* parameter values */
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/* parameter values */
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if (se->fields[i]->is_string) {
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if (se->fields[i]->is_string) {
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if (se->fields[i]->is_dynamic) {
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if (se->fields[i]->is_dynamic) {
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u32 offset, data_offset;
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union trace_synth_field *data = &entry->fields[n_u64];
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char *str_field;
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offset = (u32)entry->fields[n_u64];
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data_offset = offset & 0xffff;
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str_field = (char *)entry + data_offset;
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trace_seq_printf(s, print_fmt, se->fields[i]->name,
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trace_seq_printf(s, print_fmt, se->fields[i]->name,
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STR_VAR_LEN_MAX,
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STR_VAR_LEN_MAX,
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str_field,
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(char *)entry + data->as_dynamic.offset,
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i == se->n_fields - 1 ? "" : " ");
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i == se->n_fields - 1 ? "" : " ");
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n_u64++;
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n_u64++;
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} else {
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} else {
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trace_seq_printf(s, print_fmt, se->fields[i]->name,
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trace_seq_printf(s, print_fmt, se->fields[i]->name,
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STR_VAR_LEN_MAX,
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STR_VAR_LEN_MAX,
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(char *)&entry->fields[n_u64],
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(char *)&entry->fields[n_u64].as_u64,
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i == se->n_fields - 1 ? "" : " ");
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i == se->n_fields - 1 ? "" : " ");
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n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
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n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
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}
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}
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} else if (se->fields[i]->is_stack) {
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} else if (se->fields[i]->is_stack) {
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u32 offset, data_offset, len;
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unsigned long *p, *end;
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unsigned long *p, *end;
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union trace_synth_field *data = &entry->fields[n_u64];
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offset = (u32)entry->fields[n_u64];
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p = (void *)entry + data->as_dynamic.offset;
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data_offset = offset & 0xffff;
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end = (void *)p + data->as_dynamic.len - (sizeof(long) - 1);
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len = offset >> 16;
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p = (void *)entry + data_offset;
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end = (void *)p + len - (sizeof(long) - 1);
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trace_seq_printf(s, "%s=STACK:\n", se->fields[i]->name);
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trace_seq_printf(s, "%s=STACK:\n", se->fields[i]->name);
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@ -419,13 +409,13 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
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print_synth_event_num_val(s, print_fmt,
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print_synth_event_num_val(s, print_fmt,
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se->fields[i]->name,
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se->fields[i]->name,
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se->fields[i]->size,
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se->fields[i]->size,
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entry->fields[n_u64],
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&entry->fields[n_u64],
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space);
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space);
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if (strcmp(se->fields[i]->type, "gfp_t") == 0) {
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if (strcmp(se->fields[i]->type, "gfp_t") == 0) {
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trace_seq_puts(s, " (");
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trace_seq_puts(s, " (");
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trace_print_flags_seq(s, "|",
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trace_print_flags_seq(s, "|",
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entry->fields[n_u64],
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entry->fields[n_u64].as_u64,
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__flags);
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__flags);
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trace_seq_putc(s, ')');
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trace_seq_putc(s, ')');
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}
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}
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@ -454,21 +444,16 @@ static unsigned int trace_string(struct synth_trace_event *entry,
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int ret;
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int ret;
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if (is_dynamic) {
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if (is_dynamic) {
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u32 data_offset;
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union trace_synth_field *data = &entry->fields[*n_u64];
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data_offset = struct_size(entry, fields, event->n_u64);
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data->as_dynamic.offset = struct_size(entry, fields, event->n_u64) + data_size;
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data_offset += data_size;
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data->as_dynamic.len = fetch_store_strlen((unsigned long)str_val);
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len = fetch_store_strlen((unsigned long)str_val);
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data_offset |= len << 16;
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*(u32 *)&entry->fields[*n_u64] = data_offset;
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ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
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ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
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(*n_u64)++;
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(*n_u64)++;
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} else {
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} else {
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str_field = (char *)&entry->fields[*n_u64];
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str_field = (char *)&entry->fields[*n_u64].as_u64;
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#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
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#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
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if ((unsigned long)str_val < TASK_SIZE)
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if ((unsigned long)str_val < TASK_SIZE)
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@ -492,6 +477,7 @@ static unsigned int trace_stack(struct synth_trace_event *entry,
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unsigned int data_size,
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unsigned int data_size,
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unsigned int *n_u64)
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unsigned int *n_u64)
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{
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{
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union trace_synth_field *data = &entry->fields[*n_u64];
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unsigned int len;
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unsigned int len;
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u32 data_offset;
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u32 data_offset;
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void *data_loc;
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void *data_loc;
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@ -515,8 +501,9 @@ static unsigned int trace_stack(struct synth_trace_event *entry,
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memcpy(data_loc, stack, len);
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memcpy(data_loc, stack, len);
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/* Fill in the field that holds the offset/len combo */
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/* Fill in the field that holds the offset/len combo */
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data_offset |= len << 16;
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*(u32 *)&entry->fields[*n_u64] = data_offset;
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data->as_dynamic.offset = data_offset;
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data->as_dynamic.len = len;
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(*n_u64)++;
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(*n_u64)++;
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@ -592,19 +579,19 @@ static notrace void trace_event_raw_event_synth(void *__data,
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switch (field->size) {
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switch (field->size) {
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case 1:
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case 1:
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*(u8 *)&entry->fields[n_u64] = (u8)val;
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entry->fields[n_u64].as_u8 = (u8)val;
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break;
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break;
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case 2:
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case 2:
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*(u16 *)&entry->fields[n_u64] = (u16)val;
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entry->fields[n_u64].as_u16 = (u16)val;
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break;
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break;
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case 4:
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case 4:
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*(u32 *)&entry->fields[n_u64] = (u32)val;
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entry->fields[n_u64].as_u32 = (u32)val;
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break;
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break;
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default:
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default:
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entry->fields[n_u64] = val;
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entry->fields[n_u64].as_u64 = val;
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break;
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break;
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}
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}
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n_u64++;
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n_u64++;
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@ -1791,19 +1778,19 @@ int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
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switch (field->size) {
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switch (field->size) {
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case 1:
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case 1:
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*(u8 *)&state.entry->fields[n_u64] = (u8)val;
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state.entry->fields[n_u64].as_u8 = (u8)val;
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break;
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break;
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case 2:
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case 2:
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*(u16 *)&state.entry->fields[n_u64] = (u16)val;
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state.entry->fields[n_u64].as_u16 = (u16)val;
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break;
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break;
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case 4:
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case 4:
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*(u32 *)&state.entry->fields[n_u64] = (u32)val;
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state.entry->fields[n_u64].as_u32 = (u32)val;
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break;
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break;
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default:
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default:
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state.entry->fields[n_u64] = val;
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state.entry->fields[n_u64].as_u64 = val;
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break;
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break;
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}
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}
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n_u64++;
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n_u64++;
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@ -1884,19 +1871,19 @@ int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
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switch (field->size) {
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switch (field->size) {
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case 1:
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case 1:
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*(u8 *)&state.entry->fields[n_u64] = (u8)val;
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state.entry->fields[n_u64].as_u8 = (u8)val;
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break;
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break;
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case 2:
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case 2:
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*(u16 *)&state.entry->fields[n_u64] = (u16)val;
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state.entry->fields[n_u64].as_u16 = (u16)val;
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break;
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break;
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case 4:
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case 4:
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*(u32 *)&state.entry->fields[n_u64] = (u32)val;
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state.entry->fields[n_u64].as_u32 = (u32)val;
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break;
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break;
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default:
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default:
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state.entry->fields[n_u64] = val;
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state.entry->fields[n_u64].as_u64 = val;
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break;
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break;
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}
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}
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n_u64++;
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n_u64++;
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@ -2031,19 +2018,19 @@ static int __synth_event_add_val(const char *field_name, u64 val,
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} else {
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} else {
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switch (field->size) {
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switch (field->size) {
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case 1:
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case 1:
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*(u8 *)&trace_state->entry->fields[field->offset] = (u8)val;
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trace_state->entry->fields[field->offset].as_u8 = (u8)val;
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break;
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break;
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case 2:
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case 2:
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*(u16 *)&trace_state->entry->fields[field->offset] = (u16)val;
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trace_state->entry->fields[field->offset].as_u16 = (u16)val;
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break;
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break;
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case 4:
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case 4:
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*(u32 *)&trace_state->entry->fields[field->offset] = (u32)val;
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trace_state->entry->fields[field->offset].as_u32 = (u32)val;
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break;
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break;
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default:
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default:
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trace_state->entry->fields[field->offset] = val;
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trace_state->entry->fields[field->offset].as_u64 = val;
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break;
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break;
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}
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}
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}
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}
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