As I mentioned before, it's annoying to see this in dropreason tracing
with trace-cmd:
irq/65-iwlwifi:-401 [000] 22.790000: kfree_skb: skbaddr=0x6a89b000 protocol=0 location=ieee80211_rx_handlers_result+0x21a reason: 0x20000
and much nicer to see
irq/65-iwlwifi:-401 [000] 22.790000: kfree_skb: skbaddr=0x69142000 protocol=0 location=ieee80211_rx_handlers_result+0x21a reason: RX_DROP_MONITOR
The reason for this is that the __print_symbolic() string in tracing
for trace-cmd to parse it is created at build-time, from the long list
of _core_ drop reasons, but the drop reasons are now more dynamic.
So I came up with __print_sym() which is similar, except it doesn't
build the big list of numbers at build time but rather at runtime,
which is actually a big memory saving too. But building it then, at
the time userspace is recording it, lets us include all the known
reasons.
v2:
- rebased on 6.9-rc1
- always search for __print_sym() and get rid of the DYNPRINT flag
and associated code; I think ideally we'll just remove the older
__print_symbolic() entirely
- use ':' as the separator instead of "//" since that makes searching
for it much easier and it's still not a valid char in an identifier
- fix RCU
johannes
From: Johannes Berg <[email protected]>
The __print_symbolic() could only ever print the core
drop reasons, since that's the way the infrastructure
works. Now that we have __print_sym() with all the
advantages mentioned in that commit, convert to that
and get all the drop reasons from all subsystems. As
we already have a list of them, that's really easy.
This is a little bit of .text (~100 bytes in my build)
and saves a lot of .data (~17k).
Signed-off-by: Johannes Berg <[email protected]>
---
include/net/dropreason.h | 5 +++++
include/trace/events/skb.h | 16 +++-----------
net/core/skbuff.c | 43 ++++++++++++++++++++++++++++++++++++++
3 files changed, 51 insertions(+), 13 deletions(-)
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index 56cb7be92244..c157070b5303 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -42,6 +42,11 @@ struct drop_reason_list {
extern const struct drop_reason_list __rcu *
drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM];
+#ifdef CONFIG_TRACEPOINTS
+const char *drop_reason_lookup(unsigned long long value);
+void drop_reason_show(struct seq_file *m);
+#endif
+
void drop_reasons_register_subsys(enum skb_drop_reason_subsys subsys,
const struct drop_reason_list *list);
void drop_reasons_unregister_subsys(enum skb_drop_reason_subsys subsys);
diff --git a/include/trace/events/skb.h b/include/trace/events/skb.h
index 07e0715628ec..8a1a63f9e796 100644
--- a/include/trace/events/skb.h
+++ b/include/trace/events/skb.h
@@ -8,15 +8,9 @@
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/tracepoint.h>
+#include <net/dropreason.h>
-#undef FN
-#define FN(reason) TRACE_DEFINE_ENUM(SKB_DROP_REASON_##reason);
-DEFINE_DROP_REASON(FN, FN)
-
-#undef FN
-#undef FNe
-#define FN(reason) { SKB_DROP_REASON_##reason, #reason },
-#define FNe(reason) { SKB_DROP_REASON_##reason, #reason }
+TRACE_DEFINE_SYM_FNS(drop_reason, drop_reason_lookup, drop_reason_show);
/*
* Tracepoint for free an sk_buff:
@@ -44,13 +38,9 @@ TRACE_EVENT(kfree_skb,
TP_printk("skbaddr=%p protocol=%u location=%pS reason: %s",
__entry->skbaddr, __entry->protocol, __entry->location,
- __print_symbolic(__entry->reason,
- DEFINE_DROP_REASON(FN, FNe)))
+ __print_sym(__entry->reason, drop_reason ))
);
-#undef FN
-#undef FNe
-
TRACE_EVENT(consume_skb,
TP_PROTO(struct sk_buff *skb, void *location),
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b99127712e67..012b48da8810 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -147,6 +147,49 @@ drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
};
EXPORT_SYMBOL(drop_reasons_by_subsys);
+#ifdef CONFIG_TRACEPOINTS
+const char *drop_reason_lookup(unsigned long long value)
+{
+ unsigned long long subsys_id = value >> SKB_DROP_REASON_SUBSYS_SHIFT;
+ u32 reason = value & ~SKB_DROP_REASON_SUBSYS_MASK;
+ const struct drop_reason_list *subsys;
+
+ if (subsys_id >= SKB_DROP_REASON_SUBSYS_NUM)
+ return NULL;
+
+ subsys = rcu_dereference(drop_reasons_by_subsys[subsys_id]);
+ if (!subsys)
+ return NULL;
+ if (reason >= subsys->n_reasons)
+ return NULL;
+ return subsys->reasons[reason];
+}
+
+void drop_reason_show(struct seq_file *m)
+{
+ u32 subsys_id;
+
+ rcu_read_lock();
+ for (subsys_id = 0; subsys_id < SKB_DROP_REASON_SUBSYS_NUM; subsys_id++) {
+ const struct drop_reason_list *subsys;
+ u32 i;
+
+ subsys = rcu_dereference(drop_reasons_by_subsys[subsys_id]);
+ if (!subsys)
+ continue;
+
+ for (i = 0; i < subsys->n_reasons; i++) {
+ if (!subsys->reasons[i])
+ continue;
+ seq_printf(m, ", { %u, \"%s\" }",
+ (subsys_id << SKB_DROP_REASON_SUBSYS_SHIFT) | i,
+ subsys->reasons[i]);
+ }
+ }
+ rcu_read_unlock();
+}
+#endif
+
/**
* drop_reasons_register_subsys - register another drop reason subsystem
* @subsys: the subsystem to register, must not be the core
--
2.44.0
From: Johannes Berg <[email protected]>
Now that we have drop_reason_lookup(), we can just use it for
drop_monitor as well, rather than exporting the list itself.
Signed-off-by: Johannes Berg <[email protected]>
---
include/net/dropreason.h | 4 ----
net/core/drop_monitor.c | 18 +++---------------
net/core/skbuff.c | 6 +++---
3 files changed, 6 insertions(+), 22 deletions(-)
diff --git a/include/net/dropreason.h b/include/net/dropreason.h
index c157070b5303..0e2195ccf2cd 100644
--- a/include/net/dropreason.h
+++ b/include/net/dropreason.h
@@ -38,10 +38,6 @@ struct drop_reason_list {
size_t n_reasons;
};
-/* Note: due to dynamic registrations, access must be under RCU */
-extern const struct drop_reason_list __rcu *
-drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM];
-
#ifdef CONFIG_TRACEPOINTS
const char *drop_reason_lookup(unsigned long long value);
void drop_reason_show(struct seq_file *m);
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index b0f221d658be..185c43e5b501 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -610,9 +610,8 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
size_t payload_len)
{
struct net_dm_skb_cb *cb = NET_DM_SKB_CB(skb);
- const struct drop_reason_list *list = NULL;
- unsigned int subsys, subsys_reason;
char buf[NET_DM_MAX_SYMBOL_LEN];
+ const char *reason_str;
struct nlattr *attr;
void *hdr;
int rc;
@@ -630,19 +629,8 @@ static int net_dm_packet_report_fill(struct sk_buff *msg, struct sk_buff *skb,
goto nla_put_failure;
rcu_read_lock();
- subsys = u32_get_bits(cb->reason, SKB_DROP_REASON_SUBSYS_MASK);
- if (subsys < SKB_DROP_REASON_SUBSYS_NUM)
- list = rcu_dereference(drop_reasons_by_subsys[subsys]);
- subsys_reason = cb->reason & ~SKB_DROP_REASON_SUBSYS_MASK;
- if (!list ||
- subsys_reason >= list->n_reasons ||
- !list->reasons[subsys_reason] ||
- strlen(list->reasons[subsys_reason]) > NET_DM_MAX_REASON_LEN) {
- list = rcu_dereference(drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_CORE]);
- subsys_reason = SKB_DROP_REASON_NOT_SPECIFIED;
- }
- if (nla_put_string(msg, NET_DM_ATTR_REASON,
- list->reasons[subsys_reason])) {
+ reason_str = drop_reason_lookup(cb->reason);
+ if (nla_put_string(msg, NET_DM_ATTR_REASON, reason_str)) {
rcu_read_unlock();
goto nla_put_failure;
}
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 012b48da8810..a8065c40a270 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -141,13 +141,11 @@ static const struct drop_reason_list drop_reasons_core = {
.n_reasons = ARRAY_SIZE(drop_reasons),
};
-const struct drop_reason_list __rcu *
+static const struct drop_reason_list __rcu *
drop_reasons_by_subsys[SKB_DROP_REASON_SUBSYS_NUM] = {
[SKB_DROP_REASON_SUBSYS_CORE] = RCU_INITIALIZER(&drop_reasons_core),
};
-EXPORT_SYMBOL(drop_reasons_by_subsys);
-#ifdef CONFIG_TRACEPOINTS
const char *drop_reason_lookup(unsigned long long value)
{
unsigned long long subsys_id = value >> SKB_DROP_REASON_SUBSYS_SHIFT;
@@ -164,7 +162,9 @@ const char *drop_reason_lookup(unsigned long long value)
return NULL;
return subsys->reasons[reason];
}
+EXPORT_SYMBOL(drop_reason_lookup);
+#ifdef CONFIG_TRACEPOINTS
void drop_reason_show(struct seq_file *m)
{
u32 subsys_id;
--
2.44.0
From: Johannes Berg <[email protected]>
The way __print_symbolic() works is limited and inefficient
in multiple ways:
- you can only use it with a static list of symbols, but
e.g. the SKB dropreasons are now a dynamic list
- it builds the list in memory _three_ times, so it takes
a lot of memory:
- The print_fmt contains the list (since it's passed to
the macro there). This actually contains the names
_twice_, which is fixed up at runtime.
- TRACE_DEFINE_ENUM() puts a 24-byte struct trace_eval_map
for every entry, plus the string pointed to by it, which
cannot be deduplicated with the strings in the print_fmt
- The in-kernel symbolic printing creates yet another list
of struct trace_print_flags for trace_print_symbols_seq()
- it also requires runtime fixup during init, which is a lot
of string parsing due to the print_fmt fixup
Introduce __print_sym() to - over time - replace the old one.
We can easily extend this also to __print_flags later, but I
cared only about the SKB dropreasons for now, which has only
__print_symbolic().
This new __print_sym() requires only a single list of items,
created by TRACE_DEFINE_SYM_LIST(), or can even use another
already existing list by using TRACE_DEFINE_SYM_FNS() with
lookup and show methods.
Then, instead of doing an init-time fixup, just do this at the
time when userspace reads the print_fmt. This way, dynamically
updated lists are possible.
For userspace, nothing actually changes, because the print_fmt
is shown exactly the same way the old __print_symbolic() was.
This adds about 4k .text in my test builds, but that'll be
more than paid for by the actual conversions.
Signed-off-by: Johannes Berg <[email protected]>
---
v2:
- fix RCU
- use ':' as separator to simplify the code, that's
still not valid in a C identifier
---
include/asm-generic/vmlinux.lds.h | 3 +-
include/linux/module.h | 2 +
include/linux/trace_events.h | 7 ++
include/linux/tracepoint.h | 20 +++++
include/trace/stages/init.h | 54 +++++++++++++
include/trace/stages/stage2_data_offsets.h | 6 ++
include/trace/stages/stage3_trace_output.h | 9 +++
include/trace/stages/stage7_class_define.h | 3 +
kernel/module/main.c | 3 +
kernel/trace/trace_events.c | 90 +++++++++++++++++++++-
kernel/trace/trace_output.c | 45 +++++++++++
11 files changed, 239 insertions(+), 3 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f7749d0f2562..88de434578a5 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -256,7 +256,8 @@
#define FTRACE_EVENTS() \
. = ALIGN(8); \
BOUNDED_SECTION(_ftrace_events) \
- BOUNDED_SECTION_BY(_ftrace_eval_map, _ftrace_eval_maps)
+ BOUNDED_SECTION_BY(_ftrace_eval_map, _ftrace_eval_maps) \
+ BOUNDED_SECTION(_ftrace_sym_defs)
#else
#define FTRACE_EVENTS()
#endif
diff --git a/include/linux/module.h b/include/linux/module.h
index 1153b0d99a80..571e5e8f17b6 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -524,6 +524,8 @@ struct module {
unsigned int num_trace_events;
struct trace_eval_map **trace_evals;
unsigned int num_trace_evals;
+ struct trace_sym_def **trace_sym_defs;
+ unsigned int num_trace_sym_defs;
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
unsigned int num_ftrace_callsites;
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 6f9bdfb09d1d..bc7045d535d0 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -27,6 +27,13 @@ const char *trace_print_flags_seq(struct trace_seq *p, const char *delim,
const char *trace_print_symbols_seq(struct trace_seq *p, unsigned long val,
const struct trace_print_flags *symbol_array);
+const char *trace_print_sym_seq(struct trace_seq *p, unsigned long long val,
+ const char *(*lookup)(unsigned long long val));
+const char *trace_sym_lookup(const struct trace_sym_entry *list,
+ size_t len, unsigned long long value);
+void trace_sym_show(struct seq_file *m,
+ const struct trace_sym_entry *list, size_t len);
+
#if BITS_PER_LONG == 32
const char *trace_print_flags_seq_u64(struct trace_seq *p, const char *delim,
unsigned long long flags,
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 689b6d71590e..cc3b387953d1 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -31,6 +31,24 @@ struct trace_eval_map {
unsigned long eval_value;
};
+struct trace_sym_def {
+ const char *system;
+ const char *symbol_id;
+ /* may return NULL, called under rcu_read_lock() */
+ const char * (*lookup)(unsigned long long);
+ /*
+ * Must print the list: ', { val, "name"}, ...'
+ * with no trailing comma, but with the leading ', '
+ * to simplify things:
+ */
+ void (*show)(struct seq_file *);
+};
+
+struct trace_sym_entry {
+ unsigned long long value;
+ const char *name;
+};
+
#define TRACEPOINT_DEFAULT_PRIO 10
extern struct srcu_struct tracepoint_srcu;
@@ -109,6 +127,8 @@ extern void syscall_unregfunc(void);
#define TRACE_DEFINE_ENUM(x)
#define TRACE_DEFINE_SIZEOF(x)
+#define TRACE_DEFINE_SYM_FNS(...)
+#define TRACE_DEFINE_SYM_LIST(...)
#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
diff --git a/include/trace/stages/init.h b/include/trace/stages/init.h
index 000bcfc8dd2e..251ab22485d1 100644
--- a/include/trace/stages/init.h
+++ b/include/trace/stages/init.h
@@ -23,6 +23,60 @@ TRACE_MAKE_SYSTEM_STR();
__section("_ftrace_eval_map") \
*TRACE_SYSTEM##_##a = &__##TRACE_SYSTEM##_##a
+/*
+ * Define a symbol for __print_sym by giving lookup and
+ * show functions. See &struct trace_sym_def.
+ */
+#define TRACE_DEFINE_SYM_FNS(_symbol_id, _lookup, _show) \
+ _TRACE_DEFINE_SYM_FNS(TRACE_SYSTEM, _symbol_id, _lookup, _show)
+#define _TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show) \
+ __TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show)
+#define __TRACE_DEFINE_SYM_FNS(_system, _symbol_id, _lookup, _show) \
+ ___TRACE_DEFINE_SYM_FNS(_system ## _ ## _symbol_id, _symbol_id, \
+ _lookup, _show)
+#define ___TRACE_DEFINE_SYM_FNS(_name, _symbol_id, _lookup, _show) \
+ static struct trace_sym_def \
+ __trace_sym_def_ ## _name = { \
+ .system = TRACE_SYSTEM_STRING, \
+ /* need the ) for later strcmp */ \
+ .symbol_id = #_symbol_id ")", \
+ .lookup = _lookup, \
+ .show = _show, \
+ }; \
+ static struct trace_sym_def \
+ __section("_ftrace_sym_defs") \
+ *__trace_sym_def_p_ ## _name = &__trace_sym_def_ ## _name
+
+/*
+ * Define a symbol for __print_sym by giving lookup and
+ * show functions. See &struct trace_sym_def.
+ */
+#define TRACE_DEFINE_SYM_LIST(_symbol_id, ...) \
+ _TRACE_DEFINE_SYM_LIST(TRACE_SYSTEM, _symbol_id, __VA_ARGS__)
+#define _TRACE_DEFINE_SYM_LIST(_system, _symbol_id, ...) \
+ __TRACE_DEFINE_SYM_LIST(_system, _symbol_id, __VA_ARGS__)
+#define __TRACE_DEFINE_SYM_LIST(_system, _symbol_id, ...) \
+ ___TRACE_DEFINE_SYM_LIST(_system ## _ ## _symbol_id, _symbol_id,\
+ __VA_ARGS__)
+#define ___TRACE_DEFINE_SYM_LIST(_name, _symbol_id, ...) \
+ static struct trace_sym_entry \
+ __trace_sym_list_ ## _name[] = { __VA_ARGS__ }; \
+ static const char * \
+ __trace_sym_lookup_ ## _name(unsigned long long value) \
+ { \
+ return trace_sym_lookup(__trace_sym_list_ ## _name, \
+ ARRAY_SIZE(__trace_sym_list_ ## _name), value); \
+ } \
+ static void \
+ __trace_sym_show_ ## _name(struct seq_file *m) \
+ { \
+ trace_sym_show(m, __trace_sym_list_ ## _name, \
+ ARRAY_SIZE(__trace_sym_list_ ## _name)); \
+ } \
+ ___TRACE_DEFINE_SYM_FNS(_name, _symbol_id, \
+ __trace_sym_lookup_ ## _name, \
+ __trace_sym_show_ ## _name)
+
#undef TRACE_DEFINE_SIZEOF
#define TRACE_DEFINE_SIZEOF(a) \
static struct trace_eval_map __used __initdata \
diff --git a/include/trace/stages/stage2_data_offsets.h b/include/trace/stages/stage2_data_offsets.h
index 8b0cff06d346..5afd9de7deb3 100644
--- a/include/trace/stages/stage2_data_offsets.h
+++ b/include/trace/stages/stage2_data_offsets.h
@@ -5,6 +5,12 @@
#undef TRACE_DEFINE_ENUM
#define TRACE_DEFINE_ENUM(a)
+#undef TRACE_DEFINE_SYM_FNS
+#define TRACE_DEFINE_SYM_FNS(_symbol_id, _lookup, _show)
+
+#undef TRACE_DEFINE_SYM_LIST
+#define TRACE_DEFINE_SYM_LIST(_symbol_id, ...)
+
#undef TRACE_DEFINE_SIZEOF
#define TRACE_DEFINE_SIZEOF(a)
diff --git a/include/trace/stages/stage3_trace_output.h b/include/trace/stages/stage3_trace_output.h
index c1fb1355d309..d2c6458b62dc 100644
--- a/include/trace/stages/stage3_trace_output.h
+++ b/include/trace/stages/stage3_trace_output.h
@@ -79,6 +79,15 @@
trace_print_symbols_seq(p, value, symbols); \
})
+#undef __print_sym
+#define __print_sym(value, symbol_id) \
+ ___print_sym(TRACE_SYSTEM, value, symbol_id)
+#define ___print_sym(sys, value, symbol_id) \
+ ____print_sym(sys, value, symbol_id)
+#define ____print_sym(sys, value, symbol_id) \
+ trace_print_sym_seq(p, value, \
+ __trace_sym_def_p_ ## sys ## _ ## symbol_id->lookup)
+
#undef __print_flags_u64
#undef __print_symbolic_u64
#if BITS_PER_LONG == 32
diff --git a/include/trace/stages/stage7_class_define.h b/include/trace/stages/stage7_class_define.h
index bcb960d16fc0..cf552916935f 100644
--- a/include/trace/stages/stage7_class_define.h
+++ b/include/trace/stages/stage7_class_define.h
@@ -25,6 +25,9 @@
#undef __print_hex_dump
#undef __get_buf
+#undef __print_sym
+#define __print_sym(value, symbol_id) __print_sym(value:symbol_id)
+
/*
* The below is not executed in the kernel. It is only what is
* displayed in the print format for userspace to parse.
diff --git a/kernel/module/main.c b/kernel/module/main.c
index e1e8a7a9d6c1..babc45cbf1de 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2161,6 +2161,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
mod->trace_evals = section_objs(info, "_ftrace_eval_map",
sizeof(*mod->trace_evals),
&mod->num_trace_evals);
+ mod->trace_sym_defs = section_objs(info, "_ftrace_sym_defs",
+ sizeof(*mod->trace_sym_defs),
+ &mod->num_trace_sym_defs);
#endif
#ifdef CONFIG_TRACING
mod->trace_bprintk_fmt_start = section_objs(info, "__trace_printk_fmt",
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 7c364b87352e..24f185836dcc 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1570,6 +1570,93 @@ static void *f_next(struct seq_file *m, void *v, loff_t *pos)
return node;
}
+extern struct trace_sym_def *__start_ftrace_sym_defs[];
+extern struct trace_sym_def *__stop_ftrace_sym_defs[];
+
+static void show_sym_list(struct seq_file *m, struct trace_event_call *call,
+ const char *name)
+{
+ struct trace_sym_def **sym_defs;
+ unsigned int n_sym_defs, i;
+
+ if (call->module) {
+ struct module *mod = call->module;
+
+ sym_defs = mod->trace_sym_defs;
+ n_sym_defs = mod->num_trace_sym_defs;
+ } else {
+ sym_defs = __start_ftrace_sym_defs;
+ n_sym_defs = __stop_ftrace_sym_defs - __start_ftrace_sym_defs;
+ }
+
+ for (i = 0; i < n_sym_defs; i++) {
+ if (!sym_defs[i])
+ continue;
+ if (sym_defs[i]->system != call->class->system)
+ continue;
+ if (strncmp(name, sym_defs[i]->symbol_id,
+ strlen(sym_defs[i]->symbol_id)))
+ continue;
+ if (sym_defs[i]->show)
+ sym_defs[i]->show(m);
+ break;
+ }
+}
+
+static void show_print_fmt(struct seq_file *m, struct trace_event_call *call)
+{
+ char *ptr = call->print_fmt;
+ bool in_print_sym = false;
+ int quote = 0;
+
+ seq_puts(m, "\nprint fmt: ");
+ while (*ptr) {
+ if (*ptr == '\\') {
+ seq_putc(m, *ptr);
+ ptr++;
+ /* paranoid */
+ if (!*ptr)
+ break;
+ goto next;
+ }
+ if (*ptr == '"') {
+ quote ^= 1;
+ goto next;
+ }
+ if (quote)
+ goto next;
+
+ if (in_print_sym && *ptr != ':')
+ goto next;
+
+ if (in_print_sym && *ptr == ':') {
+ const char *name;
+
+ ptr++;
+ name = ptr;
+ /* skip the name */
+ while (*ptr && *ptr != ')')
+ ptr++;
+ /* and show the actual list inline now */
+ show_sym_list(m, call, name);
+ in_print_sym = false;
+ continue;
+ }
+
+ if (strncmp(ptr, "__print_sym(", 12) == 0) {
+ ptr += 12;
+ seq_puts(m, "__print_symbolic(");
+ in_print_sym = true;
+ continue;
+ }
+next:
+ seq_putc(m, *ptr);
+ ptr++;
+ }
+
+ seq_putc(m, '\n');
+}
+
static int f_show(struct seq_file *m, void *v)
{
struct trace_event_call *call = event_file_data(m->private);
@@ -1588,8 +1675,7 @@ static int f_show(struct seq_file *m, void *v)
return 0;
case FORMAT_PRINTFMT:
- seq_printf(m, "\nprint fmt: %s\n",
- call->print_fmt);
+ show_print_fmt(m, call);
return 0;
}
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index d8b302d01083..8a3aa661ea46 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -124,6 +124,51 @@ trace_print_symbols_seq(struct trace_seq *p, unsigned long val,
}
EXPORT_SYMBOL(trace_print_symbols_seq);
+const char *trace_sym_lookup(const struct trace_sym_entry *list,
+ size_t len, unsigned long long value)
+{
+ size_t i;
+
+ for (i = 0; i < len; i++) {
+ if (list[i].value == value)
+ return list[i].name;
+ }
+ return NULL;
+}
+EXPORT_SYMBOL(trace_sym_lookup);
+
+void trace_sym_show(struct seq_file *m,
+ const struct trace_sym_entry *list, size_t len)
+{
+ size_t i;
+
+ for (i = 0; i < len; i++)
+ seq_printf(m, ", { %lld, \"%s\" }",
+ list[i].value, list[i].name);
+}
+EXPORT_SYMBOL(trace_sym_show);
+
+const char *
+trace_print_sym_seq(struct trace_seq *p, unsigned long long val,
+ const char *(*lookup)(unsigned long long val))
+{
+ const char *ret = trace_seq_buffer_ptr(p);
+ const char *name;
+
+ rcu_read_lock();
+ name = lookup(val);
+ if (name)
+ trace_seq_puts(p, name);
+ else
+ trace_seq_printf(p, "0x%llx", val);
+ rcu_read_unlock();
+
+ trace_seq_putc(p, 0);
+
+ return ret;
+}
+EXPORT_SYMBOL(trace_print_sym_seq);
+
#if BITS_PER_LONG == 32
const char *
trace_print_flags_seq_u64(struct trace_seq *p, const char *delim,
--
2.44.0
From: Johannes Berg <[email protected]>
Use the new __print_sym() in the timer tracing, just to show
how to convert something. This adds ~80 bytes of .text for a
saving of ~1.5K of data in my builds.
Note the format changes from
print fmt: "success=%d dependency=%s", REC->success, __print_symbolic(REC->dependency, { 0, "NONE" }, { (1 << 0), "POSIX_TIMER" }, { (1 << 1), "PERF_EVENTS" }, { (1 << 2), "SCHED" }, { (1 << 3), "CLOCK_UNSTABLE" }, { (1 << 4), "RCU" }, { (1 << 5), "RCU_EXP" })
to
print fmt: "success=%d dependency=%s", REC->success, __print_symbolic(REC->dependency, { 0, "NONE" }, { 1, "POSIX_TIMER" }, { 2, "PERF_EVENTS" }, { 4, "SCHED" }, { 8, "CLOCK_UNSTABLE" }, { 16, "RCU" }, { 32, "RCU_EXP" })
Since the values are now just printed in the show function as
pure decimal values.
Signed-off-by: Johannes Berg <[email protected]>
---
include/trace/events/timer.h | 22 +++++++---------------
1 file changed, 7 insertions(+), 15 deletions(-)
diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 1ef58a04fc57..d483abffed78 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -402,26 +402,18 @@ TRACE_EVENT(itimer_expire,
#undef tick_dep_mask_name
#undef tick_dep_name_end
-/* The MASK will convert to their bits and they need to be processed too */
-#define tick_dep_name(sdep) TRACE_DEFINE_ENUM(TICK_DEP_BIT_##sdep); \
- TRACE_DEFINE_ENUM(TICK_DEP_MASK_##sdep);
-#define tick_dep_name_end(sdep) TRACE_DEFINE_ENUM(TICK_DEP_BIT_##sdep); \
- TRACE_DEFINE_ENUM(TICK_DEP_MASK_##sdep);
-/* NONE only has a mask defined for it */
-#define tick_dep_mask_name(sdep) TRACE_DEFINE_ENUM(TICK_DEP_MASK_##sdep);
-
-TICK_DEP_NAMES
-
-#undef tick_dep_name
-#undef tick_dep_mask_name
-#undef tick_dep_name_end
-
#define tick_dep_name(sdep) { TICK_DEP_MASK_##sdep, #sdep },
#define tick_dep_mask_name(sdep) { TICK_DEP_MASK_##sdep, #sdep },
#define tick_dep_name_end(sdep) { TICK_DEP_MASK_##sdep, #sdep }
+TRACE_DEFINE_SYM_LIST(tick_dep_names, TICK_DEP_NAMES);
+
+#undef tick_dep_name
+#undef tick_dep_mask_name
+#undef tick_dep_name_end
+
#define show_tick_dep_name(val) \
- __print_symbolic(val, TICK_DEP_NAMES)
+ __print_sym(val, tick_dep_names)
TRACE_EVENT(tick_stop,
--
2.44.0
On Tue, Mar 26, 2024 at 08:15:56PM +0100, Johannes Berg wrote:
> From: Johannes Berg <[email protected]>
>
> The way __print_symbolic() works is limited and inefficient
> in multiple ways:
> - you can only use it with a static list of symbols, but
> e.g. the SKB dropreasons are now a dynamic list
>
> - it builds the list in memory _three_ times, so it takes
> a lot of memory:
> - The print_fmt contains the list (since it's passed to
> the macro there). This actually contains the names
> _twice_, which is fixed up at runtime.
> - TRACE_DEFINE_ENUM() puts a 24-byte struct trace_eval_map
> for every entry, plus the string pointed to by it, which
> cannot be deduplicated with the strings in the print_fmt
> - The in-kernel symbolic printing creates yet another list
> of struct trace_print_flags for trace_print_symbols_seq()
>
> - it also requires runtime fixup during init, which is a lot
> of string parsing due to the print_fmt fixup
>
> Introduce __print_sym() to - over time - replace the old one.
> We can easily extend this also to __print_flags later, but I
> cared only about the SKB dropreasons for now, which has only
> __print_symbolic().
>
> This new __print_sym() requires only a single list of items,
> created by TRACE_DEFINE_SYM_LIST(), or can even use another
> already existing list by using TRACE_DEFINE_SYM_FNS() with
> lookup and show methods.
>
> Then, instead of doing an init-time fixup, just do this at the
> time when userspace reads the print_fmt. This way, dynamically
> updated lists are possible.
>
> For userspace, nothing actually changes, because the print_fmt
> is shown exactly the same way the old __print_symbolic() was.
>
> This adds about 4k .text in my test builds, but that'll be
> more than paid for by the actual conversions.
>
> Signed-off-by: Johannes Berg <[email protected]>
Hi Johannes,
I'm seeing some allmodconfig build problems with this applied on top of
net-next.
In file included from ./include/trace/trace_events.h:27,
from ./include/trace/define_trace.h:102,
from ./include/trace/events/module.h:134,
from kernel/module/main.c:64:
./include/trace/stages/init.h:30: warning: "TRACE_DEFINE_SYM_FNS" redefined
30 | #define TRACE_DEFINE_SYM_FNS(_symbol_id, _lookup, _show) \
|
In file included from ./include/linux/trace_events.h:11,
from kernel/module/main.c:14:
./include/linux/tracepoint.h:130: note: this is the location of the previous definition
130 | #define TRACE_DEFINE_SYM_FNS(...)
|
./include/trace/stages/init.h:54: warning: "TRACE_DEFINE_SYM_LIST" redefined
54 | #define TRACE_DEFINE_SYM_LIST(_symbol_id, ...) \
|
./include/linux/tracepoint.h:131: note: this is the location of the previous definition
131 | #define TRACE_DEFINE_SYM_LIST(...)
|
On Wed, 2024-03-27 at 21:11 +0000, Simon Horman wrote:
>
> I'm seeing some allmodconfig build problems with this applied on top of
> net-next.
> ./include/trace/stages/init.h:30: warning: "TRACE_DEFINE_SYM_FNS" redefined
> ./include/trace/stages/init.h:54: warning: "TRACE_DEFINE_SYM_LIST" redefined
Yeah, the 0-day bot reported that too, sorry about that. It needs two
lines to #undef these in init.h before their definition, just like all
other macros there. Not sure why my builds didn't show that, maybe it
doesn't affect all users.
johannes