* [PATCH v5 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
@ 2025-09-23 1:16 ` Masami Hiramatsu (Google)
2025-10-01 0:30 ` Masami Hiramatsu
2025-09-23 1:17 ` [PATCH v5 2/8] x86/hw_breakpoint: Unify breakpoint install/uninstall Masami Hiramatsu (Google)
` (6 subsequent siblings)
7 siblings, 1 reply; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:16 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a new probe event for the hardware breakpoint called wprobe-event.
This wprobe allows user to trace (watch) the memory access at the
specified memory address.
The new syntax is;
w[:[GROUP/]EVENT] [r|w|rw]@[ADDR|SYM][:SIZE] [FETCH_ARGs]
User also can use $addr to fetch the accessed address. But no other
variables are supported. To record updated value, use '+0($addr)'.
For example, tracing updates of the jiffies;
/sys/kernel/tracing # echo 'w:my_jiffies w@jiffies' >> dynamic_events
/sys/kernel/tracing # cat dynamic_events
w:wprobes/my_jiffies w@jiffies:4
/sys/kernel/tracing # echo 1 > events/wprobes/my_jiffies/enable
/sys/kernel/tracing # head -n 20 trace | tail -n 5
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
<idle>-0 [000] d.Z1. 206.547317: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
<idle>-0 [000] d.Z1. 206.548341: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
<idle>-0 [000] d.Z1. 206.549346: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v5:
- The documentation and comments have been revised accordingly.
- `default y` has been removed.
Changes in v3:
- Enclose the register-API dependent code in trace_probe.c with
CONFIG_HAVE_FUNCTION_ARG_ACCESS_API.
---
Documentation/trace/index.rst | 1
Documentation/trace/wprobetrace.rst | 69 ++++
include/linux/trace_events.h | 2
kernel/trace/Kconfig | 13 +
kernel/trace/Makefile | 1
kernel/trace/trace.c | 9
kernel/trace/trace.h | 5
kernel/trace/trace_probe.c | 22 +
kernel/trace/trace_probe.h | 8
kernel/trace/trace_wprobe.c | 685 +++++++++++++++++++++++++++++++++++
10 files changed, 812 insertions(+), 3 deletions(-)
create mode 100644 Documentation/trace/wprobetrace.rst
create mode 100644 kernel/trace/trace_wprobe.c
diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
index b4a429dc4f7a..14de6858ae1b 100644
--- a/Documentation/trace/index.rst
+++ b/Documentation/trace/index.rst
@@ -36,6 +36,7 @@ the Linux kernel.
kprobes
kprobetrace
fprobetrace
+ wprobetrace
eprobetrace
fprobe
ring-buffer-design
diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wprobetrace.rst
new file mode 100644
index 000000000000..025b4c39b809
--- /dev/null
+++ b/Documentation/trace/wprobetrace.rst
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
+Watchpoint probe (wprobe) Event Tracing
+=======================================
+
+.. Author: Masami Hiramatsu <mhiramat@kernel.org>
+
+Overview
+--------
+
+Wprobe event is a dynamic event based on the hardware breakpoint, which is
+similar to other probe events, but it is for watching data access. It allows
+you to trace which code accesses a specified data.
+
+As same as other dynamic events, wprobe events are defined via
+`dynamic_events` interface file on tracefs.
+
+Synopsis of wprobe-events
+-------------------------
+::
+
+ w:[GRP/][EVENT] SPEC [FETCHARGS] : Probe on data access
+
+ GRP : Group name for wprobe. If omitted, use "wprobes" for it.
+ EVENT : Event name for wprobe. If omitted, an event name is
+ generated based on the address or symbol.
+ SPEC : Breakpoint specification.
+ [r|w|rw]@<ADDRESS|SYMBOL[+|-OFFS]>[:LENGTH]
+
+ r|w|rw : Access type, r for read, w for write, and rw for both.
+ Default is rw if omitted.
+ ADDRESS : Address to trace (hexadecimal).
+ SYMBOL : Symbol name to trace.
+ LENGTH : Length of the data to trace in bytes. (1, 2, 4, or 8)
+
+ FETCHARGS : Arguments. Each probe can have up to 128 args.
+ $addr : Fetch the accessing address.
+ @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
+ @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
+ +|-[u]OFFS(FETCHARG) : Fetch memory at FETCHARG +|- OFFS address.(\*1)(\*2)
+ \IMM : Store an immediate value to the argument.
+ NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
+ FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
+ (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types
+ (x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr"
+ and bitfield are supported.
+
+ (\*1) this is useful for fetching a field of data structures.
+ (\*2) "u" means user-space dereference.
+
+For the details of TYPE, see :ref:`kprobetrace documentation <kprobetrace_types>`.
+
+Usage examples
+--------------
+Here is an example to add a wprobe event on a variable `jiffies`.
+::
+
+ # echo 'w:my_jiffies w@jiffies' >> dynamic_events
+ # cat dynamic_events
+ w:wprobes/my_jiffies w@jiffies
+ # echo 1 > events/wprobes/enable
+ # cat trace | head
+ # TASK-PID CPU# ||||| TIMESTAMP FUNCTION
+ # | | | ||||| | |
+ <idle>-0 [000] d.Z1. 717.026259: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
+ <idle>-0 [000] d.Z1. 717.026373: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
+
+You can see the code which writes to `jiffies` is `tick_do_update_jiffies64()`.
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 04307a19cde3..7c65f2f73ff4 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -324,6 +324,7 @@ enum {
TRACE_EVENT_FL_UPROBE_BIT,
TRACE_EVENT_FL_EPROBE_BIT,
TRACE_EVENT_FL_FPROBE_BIT,
+ TRACE_EVENT_FL_WPROBE_BIT,
TRACE_EVENT_FL_CUSTOM_BIT,
TRACE_EVENT_FL_TEST_STR_BIT,
};
@@ -354,6 +355,7 @@ enum {
TRACE_EVENT_FL_UPROBE = (1 << TRACE_EVENT_FL_UPROBE_BIT),
TRACE_EVENT_FL_EPROBE = (1 << TRACE_EVENT_FL_EPROBE_BIT),
TRACE_EVENT_FL_FPROBE = (1 << TRACE_EVENT_FL_FPROBE_BIT),
+ TRACE_EVENT_FL_WPROBE = (1 << TRACE_EVENT_FL_WPROBE_BIT),
TRACE_EVENT_FL_CUSTOM = (1 << TRACE_EVENT_FL_CUSTOM_BIT),
TRACE_EVENT_FL_TEST_STR = (1 << TRACE_EVENT_FL_TEST_STR_BIT),
};
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index d2c79da81e4f..27adf6a9ff32 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -807,6 +807,19 @@ config EPROBE_EVENTS
convert the type of an event field. For example, turn an
address into a string.
+config WPROBE_EVENTS
+ bool "Enable wprobe-based dynamic events"
+ depends on TRACING
+ depends on HAVE_HW_BREAKPOINT
+ select PROBE_EVENTS
+ select DYNAMIC_EVENTS
+ help
+ This allows the user to add watchpoint tracing events based on
+ hardware breakpoints on the fly via the ftrace interface.
+
+ Those events can be inserted wherever hardware breakpoints can be
+ set, and record accessed memory address and values.
+
config BPF_EVENTS
depends on BPF_SYSCALL
depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index dcb4e02afc5f..1d57bb36c5fc 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o
obj-$(CONFIG_FPROBE) += fprobe.o
obj-$(CONFIG_RETHOOK) += rethook.o
obj-$(CONFIG_FPROBE_EVENTS) += trace_fprobe.o
+obj-$(CONFIG_WPROBE_EVENTS) += trace_wprobe.o
obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
obj-$(CONFIG_RV) += rv/
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4283ed4e8f59..ac2fc6d768ad 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5506,8 +5506,12 @@ static const char readme_msg[] =
" uprobe_events\t\t- Create/append/remove/show the userspace dynamic events\n"
"\t\t\t Write into this file to define/undefine new trace events.\n"
#endif
+#ifdef CONFIG_WPROBE_EVENTS
+ " wprobe_events\t\t- Create/append/remove/show the hardware breakpoint dynamic events\n"
+ "\t\t\t Write into this file to define/undefine new trace events.\n"
+#endif
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS) || \
- defined(CONFIG_FPROBE_EVENTS)
+ defined(CONFIG_FPROBE_EVENTS) || defined(CONFIG_WPROBE_EVENTS)
"\t accepts: event-definitions (one definition per line)\n"
#if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
"\t Format: p[:[<group>/][<event>]] <place> [<args>]\n"
@@ -5517,6 +5521,9 @@ static const char readme_msg[] =
"\t f[:[<group>/][<event>]] <func-name>[%return] [<args>]\n"
"\t t[:[<group>/][<event>]] <tracepoint> [<args>]\n"
#endif
+#ifdef CONFIG_WPROBE_EVENTS
+ "\t w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]\n"
+#endif
#ifdef CONFIG_HIST_TRIGGERS
"\t s:[synthetic/]<event> <field> [<field>]\n"
#endif
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1dbf1d3cf2f1..ae175ddc3f58 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -173,6 +173,11 @@ struct fexit_trace_entry_head {
unsigned long ret_ip;
};
+struct wprobe_trace_entry_head {
+ struct trace_entry ent;
+ unsigned long ip;
+};
+
#define TRACE_BUF_SIZE 1024
struct trace_array;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 5b92376a58fc..d004acbeffa2 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -968,6 +968,24 @@ static int parse_probe_vars(char *orig_arg, const struct fetch_type *t,
goto inval;
}
+ /* wprobe only support "$addr" and "$value" variable */
+ if (ctx->flags & TPARG_FL_WPROBE) {
+ if (!strcmp(arg, "addr")) {
+ code->op = FETCH_OP_BADDR;
+ return 0;
+ }
+ if (!strcmp(arg, "value")) {
+ code->op = FETCH_OP_BADDR;
+ code++;
+ code->op = FETCH_OP_DEREF;
+ code->offset = 0;
+ *pcode = code;
+ return 0;
+ }
+ err = TP_ERR_BAD_VAR;
+ goto inval;
+ }
+
if (str_has_prefix(arg, "retval")) {
if (!(ctx->flags & TPARG_FL_RETURN)) {
err = TP_ERR_RETVAL_ON_PROBE;
@@ -1097,8 +1115,9 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
ret = parse_probe_vars(arg, type, pcode, end, ctx);
break;
+#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
case '%': /* named register */
- if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE)) {
+ if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE | TPARG_FL_WPROBE)) {
/* eprobe and fprobe do not handle registers */
trace_probe_log_err(ctx->offset, BAD_VAR);
break;
@@ -1111,6 +1130,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
} else
trace_probe_log_err(ctx->offset, BAD_REG_NAME);
break;
+#endif
case '@': /* memory, file-offset or symbol */
if (isdigit(arg[1])) {
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 76bf2dee8071..13c9dbc4d0e2 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -89,6 +89,7 @@ enum fetch_op {
FETCH_OP_STACK, /* Stack : .param = index */
FETCH_OP_STACKP, /* Stack pointer */
FETCH_OP_RETVAL, /* Return value */
+ FETCH_OP_BADDR, /* Break address */
FETCH_OP_IMM, /* Immediate : .immediate */
FETCH_OP_COMM, /* Current comm */
FETCH_OP_ARG, /* Function argument : .param */
@@ -396,6 +397,7 @@ static inline int traceprobe_get_entry_data_size(struct trace_probe *tp)
#define TPARG_FL_USER BIT(4)
#define TPARG_FL_FPROBE BIT(5)
#define TPARG_FL_TPOINT BIT(6)
+#define TPARG_FL_WPROBE BIT(7)
#define TPARG_FL_LOC_MASK GENMASK(4, 0)
static inline bool tparg_is_function_entry(unsigned int flags)
@@ -556,7 +558,11 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
C(BAD_TYPE4STR, "This type does not fit for string."),\
C(NEED_STRING_TYPE, "$comm and immediate-string only accepts string type"),\
C(TOO_MANY_ARGS, "Too many arguments are specified"), \
- C(TOO_MANY_EARGS, "Too many entry arguments specified"),
+ C(TOO_MANY_EARGS, "Too many entry arguments specified"), \
+ C(BAD_ACCESS_FMT, "Access memory address requires @"), \
+ C(BAD_ACCESS_TYPE, "Bad memory access type"), \
+ C(BAD_ACCESS_LEN, "This memory access length is not supported"), \
+ C(BAD_ACCESS_ADDR, "Invalid access memory address"),
#undef C
#define C(a, b) TP_ERR_##a
diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c
new file mode 100644
index 000000000000..4b00a8e917c1
--- /dev/null
+++ b/kernel/trace/trace_wprobe.c
@@ -0,0 +1,685 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hardware-breakpoint-based tracing events
+ *
+ * Copyright (C) 2023, Masami Hiramatsu <mhiramat@kernel.org>
+ */
+#define pr_fmt(fmt) "trace_wprobe: " fmt
+
+#include <linux/hw_breakpoint.h>
+#include <linux/kallsyms.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/perf_event.h>
+#include <linux/rculist.h>
+#include <linux/security.h>
+#include <linux/tracepoint.h>
+#include <linux/uaccess.h>
+
+#include <asm/ptrace.h>
+
+#include "trace_dynevent.h"
+#include "trace_probe.h"
+#include "trace_probe_kernel.h"
+#include "trace_probe_tmpl.h"
+
+#define WPROBE_EVENT_SYSTEM "wprobes"
+
+static int trace_wprobe_create(const char *raw_command);
+static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev);
+static int trace_wprobe_release(struct dyn_event *ev);
+static bool trace_wprobe_is_busy(struct dyn_event *ev);
+static bool trace_wprobe_match(const char *system, const char *event,
+ int argc, const char **argv, struct dyn_event *ev);
+
+static struct dyn_event_operations trace_wprobe_ops = {
+ .create = trace_wprobe_create,
+ .show = trace_wprobe_show,
+ .is_busy = trace_wprobe_is_busy,
+ .free = trace_wprobe_release,
+ .match = trace_wprobe_match,
+};
+
+struct trace_wprobe {
+ struct dyn_event devent;
+ struct perf_event * __percpu *bp_event;
+ unsigned long addr;
+ int len;
+ int type;
+ const char *symbol;
+ struct trace_probe tp;
+};
+
+static bool is_trace_wprobe(struct dyn_event *ev)
+{
+ return ev->ops == &trace_wprobe_ops;
+}
+
+static struct trace_wprobe *to_trace_wprobe(struct dyn_event *ev)
+{
+ return container_of(ev, struct trace_wprobe, devent);
+}
+
+#define for_each_trace_wprobe(pos, dpos) \
+ for_each_dyn_event(dpos) \
+ if (is_trace_wprobe(dpos) && (pos = to_trace_wprobe(dpos)))
+
+static bool trace_wprobe_is_busy(struct dyn_event *ev)
+{
+ struct trace_wprobe *tw = to_trace_wprobe(ev);
+
+ return trace_probe_is_enabled(&tw->tp);
+}
+
+static bool trace_wprobe_match(const char *system, const char *event,
+ int argc, const char **argv, struct dyn_event *ev)
+{
+ struct trace_wprobe *tw = to_trace_wprobe(ev);
+
+ if (event[0] != '\0' && strcmp(trace_probe_name(&tw->tp), event))
+ return false;
+
+ if (system && strcmp(trace_probe_group_name(&tw->tp), system))
+ return false;
+
+ /* TODO: match arguments */
+ return true;
+}
+
+/*
+ * Note that we don't verify the fetch_insn code, since it does not come
+ * from user space.
+ */
+static int
+process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
+ void *dest, void *base)
+{
+ void *baddr = rec;
+ unsigned long val;
+ int ret;
+
+retry:
+ /* 1st stage: get value from context */
+ switch (code->op) {
+ case FETCH_OP_BADDR:
+ val = (unsigned long)baddr;
+ break;
+ case FETCH_NOP_SYMBOL: /* Ignore a place holder */
+ code++;
+ goto retry;
+ default:
+ ret = process_common_fetch_insn(code, &val);
+ if (ret < 0)
+ return ret;
+ }
+ code++;
+
+ return process_fetch_insn_bottom(code, val, dest, base);
+}
+NOKPROBE_SYMBOL(process_fetch_insn)
+
+static void wprobe_trace_handler(struct trace_wprobe *tw,
+ struct perf_sample_data *data,
+ struct pt_regs *regs,
+ struct trace_event_file *trace_file)
+{
+ struct wprobe_trace_entry_head *entry;
+ struct trace_event_call *call = trace_probe_event_call(&tw->tp);
+ struct trace_event_buffer fbuffer;
+ int dsize;
+
+ if (WARN_ON_ONCE(call != trace_file->event_call))
+ return;
+
+ if (trace_trigger_soft_disabled(trace_file))
+ return;
+
+ dsize = __get_data_size(&tw->tp, (void *)tw->addr, NULL);
+
+ entry = trace_event_buffer_reserve(&fbuffer, trace_file,
+ sizeof(*entry) + tw->tp.size + dsize);
+ if (!entry)
+ return;
+
+ entry->ip = instruction_pointer(regs);
+ store_trace_args(&entry[1], &tw->tp, (void *)tw->addr, NULL, sizeof(*entry), dsize);
+
+ fbuffer.regs = regs;
+ trace_event_buffer_commit(&fbuffer);
+}
+
+static void wprobe_perf_handler(struct perf_event *bp,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ struct trace_wprobe *tw = bp->overflow_handler_context;
+ struct event_file_link *link;
+
+ trace_probe_for_each_link_rcu(link, &tw->tp)
+ wprobe_trace_handler(tw, data, regs, link->file);
+}
+
+static int __register_trace_wprobe(struct trace_wprobe *tw)
+{
+ struct perf_event_attr attr;
+
+ if (tw->bp_event)
+ return -EINVAL;
+
+ hw_breakpoint_init(&attr);
+ attr.bp_addr = tw->addr;
+ attr.bp_len = tw->len;
+ attr.bp_type = tw->type;
+
+ tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
+ if (IS_ERR((void * __force)tw->bp_event)) {
+ int ret = PTR_ERR((void * __force)tw->bp_event);
+
+ tw->bp_event = NULL;
+ return ret;
+ }
+
+ return 0;
+}
+
+static void __unregister_trace_wprobe(struct trace_wprobe *tw)
+{
+ if (tw->bp_event) {
+ unregister_wide_hw_breakpoint(tw->bp_event);
+ tw->bp_event = NULL;
+ }
+}
+
+static void free_trace_wprobe(struct trace_wprobe *tw)
+{
+ if (tw) {
+ trace_probe_cleanup(&tw->tp);
+ kfree(tw->symbol);
+ kfree(tw);
+ }
+}
+DEFINE_FREE(free_trace_wprobe, struct trace_wprobe *, if (!IS_ERR_OR_NULL(_T)) free_trace_wprobe(_T));
+
+static struct trace_wprobe *alloc_trace_wprobe(const char *group,
+ const char *event,
+ const char *symbol,
+ unsigned long addr,
+ int len, int type, int nargs)
+{
+ struct trace_wprobe *tw __free(free_trace_wprobe) = NULL;
+ int ret;
+
+ tw = kzalloc(struct_size(tw, tp.args, nargs), GFP_KERNEL);
+ if (!tw)
+ return ERR_PTR(-ENOMEM);
+
+ if (symbol) {
+ tw->symbol = kstrdup(symbol, GFP_KERNEL);
+ if (!tw->symbol)
+ return ERR_PTR(-ENOMEM);
+ }
+ tw->addr = addr;
+ tw->len = len;
+ tw->type = type;
+
+ ret = trace_probe_init(&tw->tp, event, group, false, nargs);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ dyn_event_init(&tw->devent, &trace_wprobe_ops);
+ return_ptr(tw);
+}
+
+static struct trace_wprobe *find_trace_wprobe(const char *event,
+ const char *group)
+{
+ struct dyn_event *pos;
+ struct trace_wprobe *tw;
+
+ for_each_trace_wprobe(tw, pos)
+ if (strcmp(trace_probe_name(&tw->tp), event) == 0 &&
+ strcmp(trace_probe_group_name(&tw->tp), group) == 0)
+ return tw;
+ return NULL;
+}
+
+static enum print_line_t
+print_wprobe_event(struct trace_iterator *iter, int flags,
+ struct trace_event *event)
+{
+ struct wprobe_trace_entry_head *field;
+ struct trace_seq *s = &iter->seq;
+ struct trace_probe *tp;
+
+ field = (struct wprobe_trace_entry_head *)iter->ent;
+ tp = trace_probe_primary_from_call(
+ container_of(event, struct trace_event_call, event));
+ if (WARN_ON_ONCE(!tp))
+ goto out;
+
+ trace_seq_printf(s, "%s: (", trace_probe_name(tp));
+
+ if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+ goto out;
+
+ trace_seq_putc(s, ')');
+
+ if (trace_probe_print_args(s, tp->args, tp->nr_args,
+ (u8 *)&field[1], field) < 0)
+ goto out;
+
+ trace_seq_putc(s, '\n');
+out:
+ return trace_handle_return(s);
+}
+
+static int wprobe_event_define_fields(struct trace_event_call *event_call)
+{
+ int ret;
+ struct wprobe_trace_entry_head field;
+ struct trace_probe *tp;
+
+ tp = trace_probe_primary_from_call(event_call);
+ if (WARN_ON_ONCE(!tp))
+ return -ENOENT;
+
+ DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+
+ return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
+}
+
+static struct trace_event_functions wprobe_funcs = {
+ .trace = print_wprobe_event
+};
+
+static struct trace_event_fields wprobe_fields_array[] = {
+ { .type = TRACE_FUNCTION_TYPE,
+ .define_fields = wprobe_event_define_fields },
+ {}
+};
+
+static int wprobe_register(struct trace_event_call *event,
+ enum trace_reg type, void *data);
+
+static inline void init_trace_event_call(struct trace_wprobe *tw)
+{
+ struct trace_event_call *call = trace_probe_event_call(&tw->tp);
+
+ call->event.funcs = &wprobe_funcs;
+ call->class->fields_array = wprobe_fields_array;
+ call->flags = TRACE_EVENT_FL_WPROBE;
+ call->class->reg = wprobe_register;
+}
+
+static int register_wprobe_event(struct trace_wprobe *tw)
+{
+ init_trace_event_call(tw);
+ return trace_probe_register_event_call(&tw->tp);
+}
+
+static int register_trace_wprobe_event(struct trace_wprobe *tw)
+{
+ struct trace_wprobe *old_tb;
+ int ret;
+
+ guard(mutex)(&event_mutex);
+
+ old_tb = find_trace_wprobe(trace_probe_name(&tw->tp),
+ trace_probe_group_name(&tw->tp));
+ if (old_tb)
+ return -EBUSY;
+
+ ret = register_wprobe_event(tw);
+ if (ret)
+ return ret;
+
+ dyn_event_add(&tw->devent, trace_probe_event_call(&tw->tp));
+ return 0;
+}
+static int unregister_wprobe_event(struct trace_wprobe *tw)
+{
+ return trace_probe_unregister_event_call(&tw->tp);
+}
+
+static int unregister_trace_wprobe(struct trace_wprobe *tw)
+{
+ if (trace_probe_has_sibling(&tw->tp))
+ goto unreg;
+
+ if (trace_probe_is_enabled(&tw->tp))
+ return -EBUSY;
+
+ if (trace_event_dyn_busy(trace_probe_event_call(&tw->tp)))
+ return -EBUSY;
+
+ if (unregister_wprobe_event(tw))
+ return -EBUSY;
+
+unreg:
+ __unregister_trace_wprobe(tw);
+ dyn_event_remove(&tw->devent);
+ trace_probe_unlink(&tw->tp);
+
+ return 0;
+}
+
+static int enable_trace_wprobe(struct trace_event_call *call,
+ struct trace_event_file *file)
+{
+ struct trace_probe *tp;
+ struct trace_wprobe *tw;
+ bool enabled;
+ int ret = 0;
+
+ tp = trace_probe_primary_from_call(call);
+ if (WARN_ON_ONCE(!tp))
+ return -ENODEV;
+ enabled = trace_probe_is_enabled(tp);
+
+ if (file) {
+ ret = trace_probe_add_file(tp, file);
+ if (ret)
+ return ret;
+ } else {
+ trace_probe_set_flag(tp, TP_FLAG_PROFILE);
+ }
+
+ if (!enabled) {
+ list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) {
+ ret = __register_trace_wprobe(tw);
+ if (ret < 0) {
+ /* TODO: rollback */
+ return ret;
+ }
+ }
+ }
+
+ return 0;
+}
+
+static int disable_trace_wprobe(struct trace_event_call *call,
+ struct trace_event_file *file)
+{
+ struct trace_wprobe *tw;
+ struct trace_probe *tp;
+
+ tp = trace_probe_primary_from_call(call);
+ if (WARN_ON_ONCE(!tp))
+ return -ENODEV;
+
+ if (file) {
+ if (!trace_probe_get_file_link(tp, file))
+ return -ENOENT;
+ if (!trace_probe_has_single_file(tp))
+ goto out;
+ trace_probe_clear_flag(tp, TP_FLAG_TRACE);
+ } else {
+ trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
+ }
+
+ if (!trace_probe_is_enabled(tp)) {
+ list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) {
+ __unregister_trace_wprobe(tw);
+ }
+ }
+
+out:
+ if (file)
+ trace_probe_remove_file(tp, file);
+
+ return 0;
+}
+
+static int wprobe_register(struct trace_event_call *event,
+ enum trace_reg type, void *data)
+{
+ struct trace_event_file *file = data;
+
+ switch (type) {
+ case TRACE_REG_REGISTER:
+ return enable_trace_wprobe(event, file);
+ case TRACE_REG_UNREGISTER:
+ return disable_trace_wprobe(event, file);
+
+#ifdef CONFIG_PERF_EVENTS
+ case TRACE_REG_PERF_REGISTER:
+ return enable_trace_wprobe(event, NULL);
+ case TRACE_REG_PERF_UNREGISTER:
+ return disable_trace_wprobe(event, NULL);
+ case TRACE_REG_PERF_OPEN:
+ case TRACE_REG_PERF_CLOSE:
+ case TRACE_REG_PERF_ADD:
+ case TRACE_REG_PERF_DEL:
+ return 0;
+#endif
+ }
+ return 0;
+}
+
+static int parse_address_spec(const char *spec, unsigned long *addr, int *type,
+ int *len, char **symbol)
+{
+ char *_spec __free(kfree) = NULL;
+ int _len = HW_BREAKPOINT_LEN_4;
+ int _type = HW_BREAKPOINT_RW;
+ unsigned long _addr = 0;
+ char *at, *col;
+
+ _spec = kstrdup(spec, GFP_KERNEL);
+ if (!_spec)
+ return -ENOMEM;
+
+ at = strchr(_spec, '@');
+ col = strchr(_spec, ':');
+
+ if (!at) {
+ trace_probe_log_err(0, BAD_ACCESS_FMT);
+ return -EINVAL;
+ }
+
+ if (at != _spec) {
+ *at = '\0';
+
+ if (strcmp(_spec, "r") == 0)
+ _type = HW_BREAKPOINT_R;
+ else if (strcmp(_spec, "w") == 0)
+ _type = HW_BREAKPOINT_W;
+ else if (strcmp(_spec, "rw") == 0)
+ _type = HW_BREAKPOINT_RW;
+ else {
+ trace_probe_log_err(0, BAD_ACCESS_TYPE);
+ return -EINVAL;
+ }
+ }
+
+ if (col) {
+ *col = '\0';
+ if (kstrtoint(col + 1, 0, &_len)) {
+ trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN);
+ return -EINVAL;
+ }
+
+ switch (_len) {
+ case 1:
+ _len = HW_BREAKPOINT_LEN_1;
+ break;
+ case 2:
+ _len = HW_BREAKPOINT_LEN_2;
+ break;
+ case 4:
+ _len = HW_BREAKPOINT_LEN_4;
+ break;
+ case 8:
+ _len = HW_BREAKPOINT_LEN_8;
+ break;
+ default:
+ trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN);
+ return -EINVAL;
+ }
+ }
+
+ if (kstrtoul(at + 1, 0, &_addr) != 0) {
+ char *off_str = strpbrk(at + 1, "+-");
+ int offset = 0;
+
+ if (off_str) {
+ if (kstrtoint(off_str, 0, &offset) != 0) {
+ trace_probe_log_err(off_str - _spec, BAD_PROBE_ADDR);
+ return -EINVAL;
+ }
+ *off_str = '\0';
+ }
+ _addr = kallsyms_lookup_name(at + 1);
+ if (!_addr) {
+ trace_probe_log_err(at + 1 - _spec, BAD_ACCESS_ADDR);
+ return -ENOENT;
+ }
+ _addr += offset;
+ *symbol = kstrdup(at + 1, GFP_KERNEL);
+ if (!*symbol)
+ return -ENOMEM;
+ }
+
+ *addr = _addr;
+ *type = _type;
+ *len = _len;
+ return 0;
+}
+
+static int __trace_wprobe_create(int argc, const char *argv[])
+{
+ /*
+ * Argument syntax:
+ * b[:[GRP/][EVENT]] SPEC
+ *
+ * SPEC:
+ * [r|w|rw]@[ADDR|SYMBOL[+OFFS]][:LEN]
+ */
+ struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
+ struct trace_wprobe *tw __free(free_trace_wprobe) = NULL;
+ const char *event = NULL, *group = WPROBE_EVENT_SYSTEM;
+ const char *tplog __free(trace_probe_log_clear) = NULL;
+ char *symbol = NULL;
+ unsigned long addr;
+ int len, type, i;
+ int ret = 0;
+
+ if (argv[0][0] != 'w')
+ return -ECANCELED;
+
+ if (argc < 2)
+ return -EINVAL;
+
+ tplog = trace_probe_log_init("wprobe", argc, argv);
+
+ if (argv[0][1] != '\0') {
+ if (argv[0][1] != ':') {
+ trace_probe_log_set_index(0);
+ trace_probe_log_err(1, BAD_MAXACT_TYPE);
+ /* Invalid format */
+ return -EINVAL;
+ }
+ event = &argv[0][2];
+ }
+
+ trace_probe_log_set_index(1);
+ ret = parse_address_spec(argv[1], &addr, &type, &len, &symbol);
+ if (ret < 0)
+ return ret;
+
+ if (!event)
+ event = symbol ? symbol : "wprobe";
+
+ argc -= 2; argv += 2;
+ tw = alloc_trace_wprobe(group, event, symbol, addr, len, type, argc);
+ if (IS_ERR(tw))
+ return PTR_ERR(tw);
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return -ENOMEM;
+
+ ctx->flags = TPARG_FL_KERNEL | TPARG_FL_WPROBE;
+
+ /* parse arguments */
+ for (i = 0; i < argc; i++) {
+ trace_probe_log_set_index(i + 2);
+ ctx->offset = 0;
+ ret = traceprobe_parse_probe_arg(&tw->tp, i, argv[i], ctx);
+ if (ret)
+ return ret; /* This can be -ENOMEM */
+ }
+
+ ret = traceprobe_set_print_fmt(&tw->tp, PROBE_PRINT_NORMAL);
+ if (ret < 0)
+ return ret;
+
+ ret = register_trace_wprobe_event(tw);
+ if (!ret)
+ tw = NULL; /* To avoid free */
+
+ return ret;
+}
+
+static int trace_wprobe_create(const char *raw_command)
+{
+ return trace_probe_create(raw_command, __trace_wprobe_create);
+}
+
+static int trace_wprobe_release(struct dyn_event *ev)
+{
+ struct trace_wprobe *tw = to_trace_wprobe(ev);
+ int ret = unregister_trace_wprobe(tw);
+
+ if (!ret)
+ free_trace_wprobe(tw);
+ return ret;
+}
+
+static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev)
+{
+ struct trace_wprobe *tw = to_trace_wprobe(ev);
+ int i;
+
+ seq_printf(m, "w:%s/%s", trace_probe_group_name(&tw->tp),
+ trace_probe_name(&tw->tp));
+
+ char type_char;
+
+ if (tw->type == HW_BREAKPOINT_R)
+ type_char = 'r';
+ else if (tw->type == HW_BREAKPOINT_W)
+ type_char = 'w';
+ else
+ type_char = 'x'; /* Should be rw */
+
+ int len;
+
+ if (tw->len == HW_BREAKPOINT_LEN_1)
+ len = 1;
+ else if (tw->len == HW_BREAKPOINT_LEN_2)
+ len = 2;
+ else if (tw->len == HW_BREAKPOINT_LEN_4)
+ len = 4;
+ else
+ len = 8;
+
+ if (tw->symbol)
+ seq_printf(m, " %c@%s:%d", type_char, tw->symbol, len);
+ else
+ seq_printf(m, " %c@0x%lx:%d", type_char, tw->addr, len);
+
+ for (i = 0; i < tw->tp.nr_args; i++)
+ seq_printf(m, " %s=%s", tw->tp.args[i].name, tw->tp.args[i].comm);
+ seq_putc(m, '\n');
+
+ return 0;
+}
+
+static __init int init_wprobe_trace(void)
+{
+ return dyn_event_register(&trace_wprobe_ops);
+}
+fs_initcall(init_wprobe_trace);
+
^ permalink raw reply related [flat|nested] 10+ messages in thread* Re: [PATCH v5 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint
2025-09-23 1:16 ` [PATCH v5 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint Masami Hiramatsu (Google)
@ 2025-10-01 0:30 ` Masami Hiramatsu
0 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu @ 2025-10-01 0:30 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86, Jinchao Wang,
Mathieu Desnoyers, Thomas Gleixner, Borislav Petkov, Dave Hansen,
H . Peter Anvin, Alexander Shishkin, Ian Rogers, linux-kernel,
linux-trace-kernel, linux-doc, linux-perf-users
On Tue, 23 Sep 2025 10:16:51 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Add a new probe event for the hardware breakpoint called wprobe-event.
> This wprobe allows user to trace (watch) the memory access at the
> specified memory address.
> The new syntax is;
>
> w[:[GROUP/]EVENT] [r|w|rw]@[ADDR|SYM][:SIZE] [FETCH_ARGs]
>
> User also can use $addr to fetch the accessed address. But no other
> variables are supported. To record updated value, use '+0($addr)'.
>
> For example, tracing updates of the jiffies;
>
> /sys/kernel/tracing # echo 'w:my_jiffies w@jiffies' >> dynamic_events
> /sys/kernel/tracing # cat dynamic_events
> w:wprobes/my_jiffies w@jiffies:4
> /sys/kernel/tracing # echo 1 > events/wprobes/my_jiffies/enable
> /sys/kernel/tracing # head -n 20 trace | tail -n 5
> # TASK-PID CPU# ||||| TIMESTAMP FUNCTION
> # | | | ||||| | |
> <idle>-0 [000] d.Z1. 206.547317: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
> <idle>-0 [000] d.Z1. 206.548341: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
> <idle>-0 [000] d.Z1. 206.549346: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
>
Let me pick this patch to probe/for-next. But others depends on
x86 and hw_breakpoint specific changes([2/8]-[4/8]), I need Peter's
Ack.
Thank you,
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---
> Changes in v5:
> - The documentation and comments have been revised accordingly.
> - `default y` has been removed.
> Changes in v3:
> - Enclose the register-API dependent code in trace_probe.c with
> CONFIG_HAVE_FUNCTION_ARG_ACCESS_API.
> ---
> Documentation/trace/index.rst | 1
> Documentation/trace/wprobetrace.rst | 69 ++++
> include/linux/trace_events.h | 2
> kernel/trace/Kconfig | 13 +
> kernel/trace/Makefile | 1
> kernel/trace/trace.c | 9
> kernel/trace/trace.h | 5
> kernel/trace/trace_probe.c | 22 +
> kernel/trace/trace_probe.h | 8
> kernel/trace/trace_wprobe.c | 685 +++++++++++++++++++++++++++++++++++
> 10 files changed, 812 insertions(+), 3 deletions(-)
> create mode 100644 Documentation/trace/wprobetrace.rst
> create mode 100644 kernel/trace/trace_wprobe.c
>
> diff --git a/Documentation/trace/index.rst b/Documentation/trace/index.rst
> index b4a429dc4f7a..14de6858ae1b 100644
> --- a/Documentation/trace/index.rst
> +++ b/Documentation/trace/index.rst
> @@ -36,6 +36,7 @@ the Linux kernel.
> kprobes
> kprobetrace
> fprobetrace
> + wprobetrace
> eprobetrace
> fprobe
> ring-buffer-design
> diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wprobetrace.rst
> new file mode 100644
> index 000000000000..025b4c39b809
> --- /dev/null
> +++ b/Documentation/trace/wprobetrace.rst
> @@ -0,0 +1,69 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=======================================
> +Watchpoint probe (wprobe) Event Tracing
> +=======================================
> +
> +.. Author: Masami Hiramatsu <mhiramat@kernel.org>
> +
> +Overview
> +--------
> +
> +Wprobe event is a dynamic event based on the hardware breakpoint, which is
> +similar to other probe events, but it is for watching data access. It allows
> +you to trace which code accesses a specified data.
> +
> +As same as other dynamic events, wprobe events are defined via
> +`dynamic_events` interface file on tracefs.
> +
> +Synopsis of wprobe-events
> +-------------------------
> +::
> +
> + w:[GRP/][EVENT] SPEC [FETCHARGS] : Probe on data access
> +
> + GRP : Group name for wprobe. If omitted, use "wprobes" for it.
> + EVENT : Event name for wprobe. If omitted, an event name is
> + generated based on the address or symbol.
> + SPEC : Breakpoint specification.
> + [r|w|rw]@<ADDRESS|SYMBOL[+|-OFFS]>[:LENGTH]
> +
> + r|w|rw : Access type, r for read, w for write, and rw for both.
> + Default is rw if omitted.
> + ADDRESS : Address to trace (hexadecimal).
> + SYMBOL : Symbol name to trace.
> + LENGTH : Length of the data to trace in bytes. (1, 2, 4, or 8)
> +
> + FETCHARGS : Arguments. Each probe can have up to 128 args.
> + $addr : Fetch the accessing address.
> + @ADDR : Fetch memory at ADDR (ADDR should be in kernel)
> + @SYM[+|-offs] : Fetch memory at SYM +|- offs (SYM should be a data symbol)
> + +|-[u]OFFS(FETCHARG) : Fetch memory at FETCHARG +|- OFFS address.(\*1)(\*2)
> + \IMM : Store an immediate value to the argument.
> + NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
> + FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
> + (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types
> + (x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr"
> + and bitfield are supported.
> +
> + (\*1) this is useful for fetching a field of data structures.
> + (\*2) "u" means user-space dereference.
> +
> +For the details of TYPE, see :ref:`kprobetrace documentation <kprobetrace_types>`.
> +
> +Usage examples
> +--------------
> +Here is an example to add a wprobe event on a variable `jiffies`.
> +::
> +
> + # echo 'w:my_jiffies w@jiffies' >> dynamic_events
> + # cat dynamic_events
> + w:wprobes/my_jiffies w@jiffies
> + # echo 1 > events/wprobes/enable
> + # cat trace | head
> + # TASK-PID CPU# ||||| TIMESTAMP FUNCTION
> + # | | | ||||| | |
> + <idle>-0 [000] d.Z1. 717.026259: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
> + <idle>-0 [000] d.Z1. 717.026373: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
> +
> +You can see the code which writes to `jiffies` is `tick_do_update_jiffies64()`.
> diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
> index 04307a19cde3..7c65f2f73ff4 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -324,6 +324,7 @@ enum {
> TRACE_EVENT_FL_UPROBE_BIT,
> TRACE_EVENT_FL_EPROBE_BIT,
> TRACE_EVENT_FL_FPROBE_BIT,
> + TRACE_EVENT_FL_WPROBE_BIT,
> TRACE_EVENT_FL_CUSTOM_BIT,
> TRACE_EVENT_FL_TEST_STR_BIT,
> };
> @@ -354,6 +355,7 @@ enum {
> TRACE_EVENT_FL_UPROBE = (1 << TRACE_EVENT_FL_UPROBE_BIT),
> TRACE_EVENT_FL_EPROBE = (1 << TRACE_EVENT_FL_EPROBE_BIT),
> TRACE_EVENT_FL_FPROBE = (1 << TRACE_EVENT_FL_FPROBE_BIT),
> + TRACE_EVENT_FL_WPROBE = (1 << TRACE_EVENT_FL_WPROBE_BIT),
> TRACE_EVENT_FL_CUSTOM = (1 << TRACE_EVENT_FL_CUSTOM_BIT),
> TRACE_EVENT_FL_TEST_STR = (1 << TRACE_EVENT_FL_TEST_STR_BIT),
> };
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index d2c79da81e4f..27adf6a9ff32 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -807,6 +807,19 @@ config EPROBE_EVENTS
> convert the type of an event field. For example, turn an
> address into a string.
>
> +config WPROBE_EVENTS
> + bool "Enable wprobe-based dynamic events"
> + depends on TRACING
> + depends on HAVE_HW_BREAKPOINT
> + select PROBE_EVENTS
> + select DYNAMIC_EVENTS
> + help
> + This allows the user to add watchpoint tracing events based on
> + hardware breakpoints on the fly via the ftrace interface.
> +
> + Those events can be inserted wherever hardware breakpoints can be
> + set, and record accessed memory address and values.
> +
> config BPF_EVENTS
> depends on BPF_SYSCALL
> depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
> diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
> index dcb4e02afc5f..1d57bb36c5fc 100644
> --- a/kernel/trace/Makefile
> +++ b/kernel/trace/Makefile
> @@ -106,6 +106,7 @@ obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o
> obj-$(CONFIG_FPROBE) += fprobe.o
> obj-$(CONFIG_RETHOOK) += rethook.o
> obj-$(CONFIG_FPROBE_EVENTS) += trace_fprobe.o
> +obj-$(CONFIG_WPROBE_EVENTS) += trace_wprobe.o
>
> obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
> obj-$(CONFIG_RV) += rv/
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 4283ed4e8f59..ac2fc6d768ad 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -5506,8 +5506,12 @@ static const char readme_msg[] =
> " uprobe_events\t\t- Create/append/remove/show the userspace dynamic events\n"
> "\t\t\t Write into this file to define/undefine new trace events.\n"
> #endif
> +#ifdef CONFIG_WPROBE_EVENTS
> + " wprobe_events\t\t- Create/append/remove/show the hardware breakpoint dynamic events\n"
> + "\t\t\t Write into this file to define/undefine new trace events.\n"
> +#endif
> #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS) || \
> - defined(CONFIG_FPROBE_EVENTS)
> + defined(CONFIG_FPROBE_EVENTS) || defined(CONFIG_WPROBE_EVENTS)
> "\t accepts: event-definitions (one definition per line)\n"
> #if defined(CONFIG_KPROBE_EVENTS) || defined(CONFIG_UPROBE_EVENTS)
> "\t Format: p[:[<group>/][<event>]] <place> [<args>]\n"
> @@ -5517,6 +5521,9 @@ static const char readme_msg[] =
> "\t f[:[<group>/][<event>]] <func-name>[%return] [<args>]\n"
> "\t t[:[<group>/][<event>]] <tracepoint> [<args>]\n"
> #endif
> +#ifdef CONFIG_WPROBE_EVENTS
> + "\t w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]\n"
> +#endif
> #ifdef CONFIG_HIST_TRIGGERS
> "\t s:[synthetic/]<event> <field> [<field>]\n"
> #endif
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 1dbf1d3cf2f1..ae175ddc3f58 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -173,6 +173,11 @@ struct fexit_trace_entry_head {
> unsigned long ret_ip;
> };
>
> +struct wprobe_trace_entry_head {
> + struct trace_entry ent;
> + unsigned long ip;
> +};
> +
> #define TRACE_BUF_SIZE 1024
>
> struct trace_array;
> diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
> index 5b92376a58fc..d004acbeffa2 100644
> --- a/kernel/trace/trace_probe.c
> +++ b/kernel/trace/trace_probe.c
> @@ -968,6 +968,24 @@ static int parse_probe_vars(char *orig_arg, const struct fetch_type *t,
> goto inval;
> }
>
> + /* wprobe only support "$addr" and "$value" variable */
> + if (ctx->flags & TPARG_FL_WPROBE) {
> + if (!strcmp(arg, "addr")) {
> + code->op = FETCH_OP_BADDR;
> + return 0;
> + }
> + if (!strcmp(arg, "value")) {
> + code->op = FETCH_OP_BADDR;
> + code++;
> + code->op = FETCH_OP_DEREF;
> + code->offset = 0;
> + *pcode = code;
> + return 0;
> + }
> + err = TP_ERR_BAD_VAR;
> + goto inval;
> + }
> +
> if (str_has_prefix(arg, "retval")) {
> if (!(ctx->flags & TPARG_FL_RETURN)) {
> err = TP_ERR_RETVAL_ON_PROBE;
> @@ -1097,8 +1115,9 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
> ret = parse_probe_vars(arg, type, pcode, end, ctx);
> break;
>
> +#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
> case '%': /* named register */
> - if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE)) {
> + if (ctx->flags & (TPARG_FL_TEVENT | TPARG_FL_FPROBE | TPARG_FL_WPROBE)) {
> /* eprobe and fprobe do not handle registers */
> trace_probe_log_err(ctx->offset, BAD_VAR);
> break;
> @@ -1111,6 +1130,7 @@ parse_probe_arg(char *arg, const struct fetch_type *type,
> } else
> trace_probe_log_err(ctx->offset, BAD_REG_NAME);
> break;
> +#endif
>
> case '@': /* memory, file-offset or symbol */
> if (isdigit(arg[1])) {
> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> index 76bf2dee8071..13c9dbc4d0e2 100644
> --- a/kernel/trace/trace_probe.h
> +++ b/kernel/trace/trace_probe.h
> @@ -89,6 +89,7 @@ enum fetch_op {
> FETCH_OP_STACK, /* Stack : .param = index */
> FETCH_OP_STACKP, /* Stack pointer */
> FETCH_OP_RETVAL, /* Return value */
> + FETCH_OP_BADDR, /* Break address */
> FETCH_OP_IMM, /* Immediate : .immediate */
> FETCH_OP_COMM, /* Current comm */
> FETCH_OP_ARG, /* Function argument : .param */
> @@ -396,6 +397,7 @@ static inline int traceprobe_get_entry_data_size(struct trace_probe *tp)
> #define TPARG_FL_USER BIT(4)
> #define TPARG_FL_FPROBE BIT(5)
> #define TPARG_FL_TPOINT BIT(6)
> +#define TPARG_FL_WPROBE BIT(7)
> #define TPARG_FL_LOC_MASK GENMASK(4, 0)
>
> static inline bool tparg_is_function_entry(unsigned int flags)
> @@ -556,7 +558,11 @@ extern int traceprobe_define_arg_fields(struct trace_event_call *event_call,
> C(BAD_TYPE4STR, "This type does not fit for string."),\
> C(NEED_STRING_TYPE, "$comm and immediate-string only accepts string type"),\
> C(TOO_MANY_ARGS, "Too many arguments are specified"), \
> - C(TOO_MANY_EARGS, "Too many entry arguments specified"),
> + C(TOO_MANY_EARGS, "Too many entry arguments specified"), \
> + C(BAD_ACCESS_FMT, "Access memory address requires @"), \
> + C(BAD_ACCESS_TYPE, "Bad memory access type"), \
> + C(BAD_ACCESS_LEN, "This memory access length is not supported"), \
> + C(BAD_ACCESS_ADDR, "Invalid access memory address"),
>
> #undef C
> #define C(a, b) TP_ERR_##a
> diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c
> new file mode 100644
> index 000000000000..4b00a8e917c1
> --- /dev/null
> +++ b/kernel/trace/trace_wprobe.c
> @@ -0,0 +1,685 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Hardware-breakpoint-based tracing events
> + *
> + * Copyright (C) 2023, Masami Hiramatsu <mhiramat@kernel.org>
> + */
> +#define pr_fmt(fmt) "trace_wprobe: " fmt
> +
> +#include <linux/hw_breakpoint.h>
> +#include <linux/kallsyms.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/perf_event.h>
> +#include <linux/rculist.h>
> +#include <linux/security.h>
> +#include <linux/tracepoint.h>
> +#include <linux/uaccess.h>
> +
> +#include <asm/ptrace.h>
> +
> +#include "trace_dynevent.h"
> +#include "trace_probe.h"
> +#include "trace_probe_kernel.h"
> +#include "trace_probe_tmpl.h"
> +
> +#define WPROBE_EVENT_SYSTEM "wprobes"
> +
> +static int trace_wprobe_create(const char *raw_command);
> +static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev);
> +static int trace_wprobe_release(struct dyn_event *ev);
> +static bool trace_wprobe_is_busy(struct dyn_event *ev);
> +static bool trace_wprobe_match(const char *system, const char *event,
> + int argc, const char **argv, struct dyn_event *ev);
> +
> +static struct dyn_event_operations trace_wprobe_ops = {
> + .create = trace_wprobe_create,
> + .show = trace_wprobe_show,
> + .is_busy = trace_wprobe_is_busy,
> + .free = trace_wprobe_release,
> + .match = trace_wprobe_match,
> +};
> +
> +struct trace_wprobe {
> + struct dyn_event devent;
> + struct perf_event * __percpu *bp_event;
> + unsigned long addr;
> + int len;
> + int type;
> + const char *symbol;
> + struct trace_probe tp;
> +};
> +
> +static bool is_trace_wprobe(struct dyn_event *ev)
> +{
> + return ev->ops == &trace_wprobe_ops;
> +}
> +
> +static struct trace_wprobe *to_trace_wprobe(struct dyn_event *ev)
> +{
> + return container_of(ev, struct trace_wprobe, devent);
> +}
> +
> +#define for_each_trace_wprobe(pos, dpos) \
> + for_each_dyn_event(dpos) \
> + if (is_trace_wprobe(dpos) && (pos = to_trace_wprobe(dpos)))
> +
> +static bool trace_wprobe_is_busy(struct dyn_event *ev)
> +{
> + struct trace_wprobe *tw = to_trace_wprobe(ev);
> +
> + return trace_probe_is_enabled(&tw->tp);
> +}
> +
> +static bool trace_wprobe_match(const char *system, const char *event,
> + int argc, const char **argv, struct dyn_event *ev)
> +{
> + struct trace_wprobe *tw = to_trace_wprobe(ev);
> +
> + if (event[0] != '\0' && strcmp(trace_probe_name(&tw->tp), event))
> + return false;
> +
> + if (system && strcmp(trace_probe_group_name(&tw->tp), system))
> + return false;
> +
> + /* TODO: match arguments */
> + return true;
> +}
> +
> +/*
> + * Note that we don't verify the fetch_insn code, since it does not come
> + * from user space.
> + */
> +static int
> +process_fetch_insn(struct fetch_insn *code, void *rec, void *edata,
> + void *dest, void *base)
> +{
> + void *baddr = rec;
> + unsigned long val;
> + int ret;
> +
> +retry:
> + /* 1st stage: get value from context */
> + switch (code->op) {
> + case FETCH_OP_BADDR:
> + val = (unsigned long)baddr;
> + break;
> + case FETCH_NOP_SYMBOL: /* Ignore a place holder */
> + code++;
> + goto retry;
> + default:
> + ret = process_common_fetch_insn(code, &val);
> + if (ret < 0)
> + return ret;
> + }
> + code++;
> +
> + return process_fetch_insn_bottom(code, val, dest, base);
> +}
> +NOKPROBE_SYMBOL(process_fetch_insn)
> +
> +static void wprobe_trace_handler(struct trace_wprobe *tw,
> + struct perf_sample_data *data,
> + struct pt_regs *regs,
> + struct trace_event_file *trace_file)
> +{
> + struct wprobe_trace_entry_head *entry;
> + struct trace_event_call *call = trace_probe_event_call(&tw->tp);
> + struct trace_event_buffer fbuffer;
> + int dsize;
> +
> + if (WARN_ON_ONCE(call != trace_file->event_call))
> + return;
> +
> + if (trace_trigger_soft_disabled(trace_file))
> + return;
> +
> + dsize = __get_data_size(&tw->tp, (void *)tw->addr, NULL);
> +
> + entry = trace_event_buffer_reserve(&fbuffer, trace_file,
> + sizeof(*entry) + tw->tp.size + dsize);
> + if (!entry)
> + return;
> +
> + entry->ip = instruction_pointer(regs);
> + store_trace_args(&entry[1], &tw->tp, (void *)tw->addr, NULL, sizeof(*entry), dsize);
> +
> + fbuffer.regs = regs;
> + trace_event_buffer_commit(&fbuffer);
> +}
> +
> +static void wprobe_perf_handler(struct perf_event *bp,
> + struct perf_sample_data *data,
> + struct pt_regs *regs)
> +{
> + struct trace_wprobe *tw = bp->overflow_handler_context;
> + struct event_file_link *link;
> +
> + trace_probe_for_each_link_rcu(link, &tw->tp)
> + wprobe_trace_handler(tw, data, regs, link->file);
> +}
> +
> +static int __register_trace_wprobe(struct trace_wprobe *tw)
> +{
> + struct perf_event_attr attr;
> +
> + if (tw->bp_event)
> + return -EINVAL;
> +
> + hw_breakpoint_init(&attr);
> + attr.bp_addr = tw->addr;
> + attr.bp_len = tw->len;
> + attr.bp_type = tw->type;
> +
> + tw->bp_event = register_wide_hw_breakpoint(&attr, wprobe_perf_handler, tw);
> + if (IS_ERR((void * __force)tw->bp_event)) {
> + int ret = PTR_ERR((void * __force)tw->bp_event);
> +
> + tw->bp_event = NULL;
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static void __unregister_trace_wprobe(struct trace_wprobe *tw)
> +{
> + if (tw->bp_event) {
> + unregister_wide_hw_breakpoint(tw->bp_event);
> + tw->bp_event = NULL;
> + }
> +}
> +
> +static void free_trace_wprobe(struct trace_wprobe *tw)
> +{
> + if (tw) {
> + trace_probe_cleanup(&tw->tp);
> + kfree(tw->symbol);
> + kfree(tw);
> + }
> +}
> +DEFINE_FREE(free_trace_wprobe, struct trace_wprobe *, if (!IS_ERR_OR_NULL(_T)) free_trace_wprobe(_T));
> +
> +static struct trace_wprobe *alloc_trace_wprobe(const char *group,
> + const char *event,
> + const char *symbol,
> + unsigned long addr,
> + int len, int type, int nargs)
> +{
> + struct trace_wprobe *tw __free(free_trace_wprobe) = NULL;
> + int ret;
> +
> + tw = kzalloc(struct_size(tw, tp.args, nargs), GFP_KERNEL);
> + if (!tw)
> + return ERR_PTR(-ENOMEM);
> +
> + if (symbol) {
> + tw->symbol = kstrdup(symbol, GFP_KERNEL);
> + if (!tw->symbol)
> + return ERR_PTR(-ENOMEM);
> + }
> + tw->addr = addr;
> + tw->len = len;
> + tw->type = type;
> +
> + ret = trace_probe_init(&tw->tp, event, group, false, nargs);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + dyn_event_init(&tw->devent, &trace_wprobe_ops);
> + return_ptr(tw);
> +}
> +
> +static struct trace_wprobe *find_trace_wprobe(const char *event,
> + const char *group)
> +{
> + struct dyn_event *pos;
> + struct trace_wprobe *tw;
> +
> + for_each_trace_wprobe(tw, pos)
> + if (strcmp(trace_probe_name(&tw->tp), event) == 0 &&
> + strcmp(trace_probe_group_name(&tw->tp), group) == 0)
> + return tw;
> + return NULL;
> +}
> +
> +static enum print_line_t
> +print_wprobe_event(struct trace_iterator *iter, int flags,
> + struct trace_event *event)
> +{
> + struct wprobe_trace_entry_head *field;
> + struct trace_seq *s = &iter->seq;
> + struct trace_probe *tp;
> +
> + field = (struct wprobe_trace_entry_head *)iter->ent;
> + tp = trace_probe_primary_from_call(
> + container_of(event, struct trace_event_call, event));
> + if (WARN_ON_ONCE(!tp))
> + goto out;
> +
> + trace_seq_printf(s, "%s: (", trace_probe_name(tp));
> +
> + if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
> + goto out;
> +
> + trace_seq_putc(s, ')');
> +
> + if (trace_probe_print_args(s, tp->args, tp->nr_args,
> + (u8 *)&field[1], field) < 0)
> + goto out;
> +
> + trace_seq_putc(s, '\n');
> +out:
> + return trace_handle_return(s);
> +}
> +
> +static int wprobe_event_define_fields(struct trace_event_call *event_call)
> +{
> + int ret;
> + struct wprobe_trace_entry_head field;
> + struct trace_probe *tp;
> +
> + tp = trace_probe_primary_from_call(event_call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENOENT;
> +
> + DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
> +
> + return traceprobe_define_arg_fields(event_call, sizeof(field), tp);
> +}
> +
> +static struct trace_event_functions wprobe_funcs = {
> + .trace = print_wprobe_event
> +};
> +
> +static struct trace_event_fields wprobe_fields_array[] = {
> + { .type = TRACE_FUNCTION_TYPE,
> + .define_fields = wprobe_event_define_fields },
> + {}
> +};
> +
> +static int wprobe_register(struct trace_event_call *event,
> + enum trace_reg type, void *data);
> +
> +static inline void init_trace_event_call(struct trace_wprobe *tw)
> +{
> + struct trace_event_call *call = trace_probe_event_call(&tw->tp);
> +
> + call->event.funcs = &wprobe_funcs;
> + call->class->fields_array = wprobe_fields_array;
> + call->flags = TRACE_EVENT_FL_WPROBE;
> + call->class->reg = wprobe_register;
> +}
> +
> +static int register_wprobe_event(struct trace_wprobe *tw)
> +{
> + init_trace_event_call(tw);
> + return trace_probe_register_event_call(&tw->tp);
> +}
> +
> +static int register_trace_wprobe_event(struct trace_wprobe *tw)
> +{
> + struct trace_wprobe *old_tb;
> + int ret;
> +
> + guard(mutex)(&event_mutex);
> +
> + old_tb = find_trace_wprobe(trace_probe_name(&tw->tp),
> + trace_probe_group_name(&tw->tp));
> + if (old_tb)
> + return -EBUSY;
> +
> + ret = register_wprobe_event(tw);
> + if (ret)
> + return ret;
> +
> + dyn_event_add(&tw->devent, trace_probe_event_call(&tw->tp));
> + return 0;
> +}
> +static int unregister_wprobe_event(struct trace_wprobe *tw)
> +{
> + return trace_probe_unregister_event_call(&tw->tp);
> +}
> +
> +static int unregister_trace_wprobe(struct trace_wprobe *tw)
> +{
> + if (trace_probe_has_sibling(&tw->tp))
> + goto unreg;
> +
> + if (trace_probe_is_enabled(&tw->tp))
> + return -EBUSY;
> +
> + if (trace_event_dyn_busy(trace_probe_event_call(&tw->tp)))
> + return -EBUSY;
> +
> + if (unregister_wprobe_event(tw))
> + return -EBUSY;
> +
> +unreg:
> + __unregister_trace_wprobe(tw);
> + dyn_event_remove(&tw->devent);
> + trace_probe_unlink(&tw->tp);
> +
> + return 0;
> +}
> +
> +static int enable_trace_wprobe(struct trace_event_call *call,
> + struct trace_event_file *file)
> +{
> + struct trace_probe *tp;
> + struct trace_wprobe *tw;
> + bool enabled;
> + int ret = 0;
> +
> + tp = trace_probe_primary_from_call(call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENODEV;
> + enabled = trace_probe_is_enabled(tp);
> +
> + if (file) {
> + ret = trace_probe_add_file(tp, file);
> + if (ret)
> + return ret;
> + } else {
> + trace_probe_set_flag(tp, TP_FLAG_PROFILE);
> + }
> +
> + if (!enabled) {
> + list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) {
> + ret = __register_trace_wprobe(tw);
> + if (ret < 0) {
> + /* TODO: rollback */
> + return ret;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> +static int disable_trace_wprobe(struct trace_event_call *call,
> + struct trace_event_file *file)
> +{
> + struct trace_wprobe *tw;
> + struct trace_probe *tp;
> +
> + tp = trace_probe_primary_from_call(call);
> + if (WARN_ON_ONCE(!tp))
> + return -ENODEV;
> +
> + if (file) {
> + if (!trace_probe_get_file_link(tp, file))
> + return -ENOENT;
> + if (!trace_probe_has_single_file(tp))
> + goto out;
> + trace_probe_clear_flag(tp, TP_FLAG_TRACE);
> + } else {
> + trace_probe_clear_flag(tp, TP_FLAG_PROFILE);
> + }
> +
> + if (!trace_probe_is_enabled(tp)) {
> + list_for_each_entry(tw, trace_probe_probe_list(tp), tp.list) {
> + __unregister_trace_wprobe(tw);
> + }
> + }
> +
> +out:
> + if (file)
> + trace_probe_remove_file(tp, file);
> +
> + return 0;
> +}
> +
> +static int wprobe_register(struct trace_event_call *event,
> + enum trace_reg type, void *data)
> +{
> + struct trace_event_file *file = data;
> +
> + switch (type) {
> + case TRACE_REG_REGISTER:
> + return enable_trace_wprobe(event, file);
> + case TRACE_REG_UNREGISTER:
> + return disable_trace_wprobe(event, file);
> +
> +#ifdef CONFIG_PERF_EVENTS
> + case TRACE_REG_PERF_REGISTER:
> + return enable_trace_wprobe(event, NULL);
> + case TRACE_REG_PERF_UNREGISTER:
> + return disable_trace_wprobe(event, NULL);
> + case TRACE_REG_PERF_OPEN:
> + case TRACE_REG_PERF_CLOSE:
> + case TRACE_REG_PERF_ADD:
> + case TRACE_REG_PERF_DEL:
> + return 0;
> +#endif
> + }
> + return 0;
> +}
> +
> +static int parse_address_spec(const char *spec, unsigned long *addr, int *type,
> + int *len, char **symbol)
> +{
> + char *_spec __free(kfree) = NULL;
> + int _len = HW_BREAKPOINT_LEN_4;
> + int _type = HW_BREAKPOINT_RW;
> + unsigned long _addr = 0;
> + char *at, *col;
> +
> + _spec = kstrdup(spec, GFP_KERNEL);
> + if (!_spec)
> + return -ENOMEM;
> +
> + at = strchr(_spec, '@');
> + col = strchr(_spec, ':');
> +
> + if (!at) {
> + trace_probe_log_err(0, BAD_ACCESS_FMT);
> + return -EINVAL;
> + }
> +
> + if (at != _spec) {
> + *at = '\0';
> +
> + if (strcmp(_spec, "r") == 0)
> + _type = HW_BREAKPOINT_R;
> + else if (strcmp(_spec, "w") == 0)
> + _type = HW_BREAKPOINT_W;
> + else if (strcmp(_spec, "rw") == 0)
> + _type = HW_BREAKPOINT_RW;
> + else {
> + trace_probe_log_err(0, BAD_ACCESS_TYPE);
> + return -EINVAL;
> + }
> + }
> +
> + if (col) {
> + *col = '\0';
> + if (kstrtoint(col + 1, 0, &_len)) {
> + trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN);
> + return -EINVAL;
> + }
> +
> + switch (_len) {
> + case 1:
> + _len = HW_BREAKPOINT_LEN_1;
> + break;
> + case 2:
> + _len = HW_BREAKPOINT_LEN_2;
> + break;
> + case 4:
> + _len = HW_BREAKPOINT_LEN_4;
> + break;
> + case 8:
> + _len = HW_BREAKPOINT_LEN_8;
> + break;
> + default:
> + trace_probe_log_err(col + 1 - _spec, BAD_ACCESS_LEN);
> + return -EINVAL;
> + }
> + }
> +
> + if (kstrtoul(at + 1, 0, &_addr) != 0) {
> + char *off_str = strpbrk(at + 1, "+-");
> + int offset = 0;
> +
> + if (off_str) {
> + if (kstrtoint(off_str, 0, &offset) != 0) {
> + trace_probe_log_err(off_str - _spec, BAD_PROBE_ADDR);
> + return -EINVAL;
> + }
> + *off_str = '\0';
> + }
> + _addr = kallsyms_lookup_name(at + 1);
> + if (!_addr) {
> + trace_probe_log_err(at + 1 - _spec, BAD_ACCESS_ADDR);
> + return -ENOENT;
> + }
> + _addr += offset;
> + *symbol = kstrdup(at + 1, GFP_KERNEL);
> + if (!*symbol)
> + return -ENOMEM;
> + }
> +
> + *addr = _addr;
> + *type = _type;
> + *len = _len;
> + return 0;
> +}
> +
> +static int __trace_wprobe_create(int argc, const char *argv[])
> +{
> + /*
> + * Argument syntax:
> + * b[:[GRP/][EVENT]] SPEC
> + *
> + * SPEC:
> + * [r|w|rw]@[ADDR|SYMBOL[+OFFS]][:LEN]
> + */
> + struct traceprobe_parse_context *ctx __free(traceprobe_parse_context) = NULL;
> + struct trace_wprobe *tw __free(free_trace_wprobe) = NULL;
> + const char *event = NULL, *group = WPROBE_EVENT_SYSTEM;
> + const char *tplog __free(trace_probe_log_clear) = NULL;
> + char *symbol = NULL;
> + unsigned long addr;
> + int len, type, i;
> + int ret = 0;
> +
> + if (argv[0][0] != 'w')
> + return -ECANCELED;
> +
> + if (argc < 2)
> + return -EINVAL;
> +
> + tplog = trace_probe_log_init("wprobe", argc, argv);
> +
> + if (argv[0][1] != '\0') {
> + if (argv[0][1] != ':') {
> + trace_probe_log_set_index(0);
> + trace_probe_log_err(1, BAD_MAXACT_TYPE);
> + /* Invalid format */
> + return -EINVAL;
> + }
> + event = &argv[0][2];
> + }
> +
> + trace_probe_log_set_index(1);
> + ret = parse_address_spec(argv[1], &addr, &type, &len, &symbol);
> + if (ret < 0)
> + return ret;
> +
> + if (!event)
> + event = symbol ? symbol : "wprobe";
> +
> + argc -= 2; argv += 2;
> + tw = alloc_trace_wprobe(group, event, symbol, addr, len, type, argc);
> + if (IS_ERR(tw))
> + return PTR_ERR(tw);
> +
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (!ctx)
> + return -ENOMEM;
> +
> + ctx->flags = TPARG_FL_KERNEL | TPARG_FL_WPROBE;
> +
> + /* parse arguments */
> + for (i = 0; i < argc; i++) {
> + trace_probe_log_set_index(i + 2);
> + ctx->offset = 0;
> + ret = traceprobe_parse_probe_arg(&tw->tp, i, argv[i], ctx);
> + if (ret)
> + return ret; /* This can be -ENOMEM */
> + }
> +
> + ret = traceprobe_set_print_fmt(&tw->tp, PROBE_PRINT_NORMAL);
> + if (ret < 0)
> + return ret;
> +
> + ret = register_trace_wprobe_event(tw);
> + if (!ret)
> + tw = NULL; /* To avoid free */
> +
> + return ret;
> +}
> +
> +static int trace_wprobe_create(const char *raw_command)
> +{
> + return trace_probe_create(raw_command, __trace_wprobe_create);
> +}
> +
> +static int trace_wprobe_release(struct dyn_event *ev)
> +{
> + struct trace_wprobe *tw = to_trace_wprobe(ev);
> + int ret = unregister_trace_wprobe(tw);
> +
> + if (!ret)
> + free_trace_wprobe(tw);
> + return ret;
> +}
> +
> +static int trace_wprobe_show(struct seq_file *m, struct dyn_event *ev)
> +{
> + struct trace_wprobe *tw = to_trace_wprobe(ev);
> + int i;
> +
> + seq_printf(m, "w:%s/%s", trace_probe_group_name(&tw->tp),
> + trace_probe_name(&tw->tp));
> +
> + char type_char;
> +
> + if (tw->type == HW_BREAKPOINT_R)
> + type_char = 'r';
> + else if (tw->type == HW_BREAKPOINT_W)
> + type_char = 'w';
> + else
> + type_char = 'x'; /* Should be rw */
> +
> + int len;
> +
> + if (tw->len == HW_BREAKPOINT_LEN_1)
> + len = 1;
> + else if (tw->len == HW_BREAKPOINT_LEN_2)
> + len = 2;
> + else if (tw->len == HW_BREAKPOINT_LEN_4)
> + len = 4;
> + else
> + len = 8;
> +
> + if (tw->symbol)
> + seq_printf(m, " %c@%s:%d", type_char, tw->symbol, len);
> + else
> + seq_printf(m, " %c@0x%lx:%d", type_char, tw->addr, len);
> +
> + for (i = 0; i < tw->tp.nr_args; i++)
> + seq_printf(m, " %s=%s", tw->tp.args[i].name, tw->tp.args[i].comm);
> + seq_putc(m, '\n');
> +
> + return 0;
> +}
> +
> +static __init int init_wprobe_trace(void)
> +{
> + return dyn_event_register(&trace_wprobe_ops);
> +}
> +fs_initcall(init_wprobe_trace);
> +
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH v5 2/8] x86/hw_breakpoint: Unify breakpoint install/uninstall
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
2025-09-23 1:16 ` [PATCH v5 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 3/8] x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint Masami Hiramatsu (Google)
` (5 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Jinchao Wang <wangjinchao600@gmail.com>
Consolidate breakpoint management to reduce code duplication.
The diffstat was misleading, so the stripped code size is compared instead.
After refactoring, it is reduced from 11976 bytes to 11448 bytes on my
x86_64 system built with clang.
This also makes it easier to introduce arch_reinstall_hw_breakpoint().
In addition, including linux/types.h to fix a missing build dependency.
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
arch/x86/include/asm/hw_breakpoint.h | 6 +
arch/x86/kernel/hw_breakpoint.c | 141 +++++++++++++++++++---------------
2 files changed, 84 insertions(+), 63 deletions(-)
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
index 0bc931cd0698..aa6adac6c3a2 100644
--- a/arch/x86/include/asm/hw_breakpoint.h
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -5,6 +5,7 @@
#include <uapi/asm/hw_breakpoint.h>
#define __ARCH_HW_BREAKPOINT_H
+#include <linux/types.h>
/*
* The name should probably be something dealt in
@@ -18,6 +19,11 @@ struct arch_hw_breakpoint {
u8 type;
};
+enum bp_slot_action {
+ BP_SLOT_ACTION_INSTALL,
+ BP_SLOT_ACTION_UNINSTALL,
+};
+
#include <linux/kdebug.h>
#include <linux/percpu.h>
#include <linux/list.h>
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index b01644c949b2..3658ace4bd8d 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -48,7 +48,6 @@ static DEFINE_PER_CPU(unsigned long, cpu_debugreg[HBP_NUM]);
*/
static DEFINE_PER_CPU(struct perf_event *, bp_per_reg[HBP_NUM]);
-
static inline unsigned long
__encode_dr7(int drnum, unsigned int len, unsigned int type)
{
@@ -85,96 +84,112 @@ int decode_dr7(unsigned long dr7, int bpnum, unsigned *len, unsigned *type)
}
/*
- * Install a perf counter breakpoint.
- *
- * We seek a free debug address register and use it for this
- * breakpoint. Eventually we enable it in the debug control register.
- *
- * Atomic: we hold the counter->ctx->lock and we only handle variables
- * and registers local to this cpu.
+ * We seek a slot and change it or keep it based on the action.
+ * Returns slot number on success, negative error on failure.
+ * Must be called with IRQs disabled.
*/
-int arch_install_hw_breakpoint(struct perf_event *bp)
+static int manage_bp_slot(struct perf_event *bp, enum bp_slot_action action)
{
- struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- unsigned long *dr7;
- int i;
-
- lockdep_assert_irqs_disabled();
+ struct perf_event *old_bp;
+ struct perf_event *new_bp;
+ int slot;
+
+ switch (action) {
+ case BP_SLOT_ACTION_INSTALL:
+ old_bp = NULL;
+ new_bp = bp;
+ break;
+ case BP_SLOT_ACTION_UNINSTALL:
+ old_bp = bp;
+ new_bp = NULL;
+ break;
+ default:
+ return -EINVAL;
+ }
- for (i = 0; i < HBP_NUM; i++) {
- struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]);
+ for (slot = 0; slot < HBP_NUM; slot++) {
+ struct perf_event **curr = this_cpu_ptr(&bp_per_reg[slot]);
- if (!*slot) {
- *slot = bp;
- break;
+ if (*curr == old_bp) {
+ *curr = new_bp;
+ return slot;
}
}
- if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
- return -EBUSY;
+ if (old_bp) {
+ WARN_ONCE(1, "Can't find matching breakpoint slot");
+ return -EINVAL;
+ }
+
+ WARN_ONCE(1, "No free breakpoint slots");
+ return -EBUSY;
+}
+
+static void setup_hwbp(struct arch_hw_breakpoint *info, int slot, bool enable)
+{
+ unsigned long dr7;
- set_debugreg(info->address, i);
- __this_cpu_write(cpu_debugreg[i], info->address);
+ set_debugreg(info->address, slot);
+ __this_cpu_write(cpu_debugreg[slot], info->address);
- dr7 = this_cpu_ptr(&cpu_dr7);
- *dr7 |= encode_dr7(i, info->len, info->type);
+ dr7 = this_cpu_read(cpu_dr7);
+ if (enable)
+ dr7 |= encode_dr7(slot, info->len, info->type);
+ else
+ dr7 &= ~__encode_dr7(slot, info->len, info->type);
/*
- * Ensure we first write cpu_dr7 before we set the DR7 register.
- * This ensures an NMI never see cpu_dr7 0 when DR7 is not.
+ * Enabling:
+ * Ensure we first write cpu_dr7 before we set the DR7 register.
+ * This ensures an NMI never see cpu_dr7 0 when DR7 is not.
*/
+ if (enable)
+ this_cpu_write(cpu_dr7, dr7);
+
barrier();
- set_debugreg(*dr7, 7);
+ set_debugreg(dr7, 7);
+
if (info->mask)
- amd_set_dr_addr_mask(info->mask, i);
+ amd_set_dr_addr_mask(enable ? info->mask : 0, slot);
- return 0;
+ /*
+ * Disabling:
+ * Ensure the write to cpu_dr7 is after we've set the DR7 register.
+ * This ensures an NMI never see cpu_dr7 0 when DR7 is not.
+ */
+ if (!enable)
+ this_cpu_write(cpu_dr7, dr7);
}
/*
- * Uninstall the breakpoint contained in the given counter.
- *
- * First we search the debug address register it uses and then we disable
- * it.
- *
- * Atomic: we hold the counter->ctx->lock and we only handle variables
- * and registers local to this cpu.
+ * find suitable breakpoint slot and set it up based on the action
*/
-void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+static int arch_manage_bp(struct perf_event *bp, enum bp_slot_action action)
{
- struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- unsigned long dr7;
- int i;
+ struct arch_hw_breakpoint *info;
+ int slot;
lockdep_assert_irqs_disabled();
- for (i = 0; i < HBP_NUM; i++) {
- struct perf_event **slot = this_cpu_ptr(&bp_per_reg[i]);
-
- if (*slot == bp) {
- *slot = NULL;
- break;
- }
- }
-
- if (WARN_ONCE(i == HBP_NUM, "Can't find any breakpoint slot"))
- return;
+ slot = manage_bp_slot(bp, action);
+ if (slot < 0)
+ return slot;
- dr7 = this_cpu_read(cpu_dr7);
- dr7 &= ~__encode_dr7(i, info->len, info->type);
+ info = counter_arch_bp(bp);
+ setup_hwbp(info, slot, action != BP_SLOT_ACTION_UNINSTALL);
- set_debugreg(dr7, 7);
- if (info->mask)
- amd_set_dr_addr_mask(0, i);
+ return 0;
+}
- /*
- * Ensure the write to cpu_dr7 is after we've set the DR7 register.
- * This ensures an NMI never see cpu_dr7 0 when DR7 is not.
- */
- barrier();
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+ return arch_manage_bp(bp, BP_SLOT_ACTION_INSTALL);
+}
- this_cpu_write(cpu_dr7, dr7);
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+ arch_manage_bp(bp, BP_SLOT_ACTION_UNINSTALL);
}
static int arch_bp_generic_len(int x86_len)
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 3/8] x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
2025-09-23 1:16 ` [PATCH v5 1/8] tracing: wprobe: Add watchpoint probe event based on hardware breakpoint Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 2/8] x86/hw_breakpoint: Unify breakpoint install/uninstall Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 4/8] HWBP: Add modify_wide_hw_breakpoint_local() API Masami Hiramatsu (Google)
` (4 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Jinchao Wang <wangjinchao600@gmail.com>
The new arch_reinstall_hw_breakpoint() function can be used in an
atomic context, unlike the more expensive free and re-allocation path.
This allows callers to efficiently re-establish an existing breakpoint.
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
arch/x86/include/asm/hw_breakpoint.h | 2 ++
arch/x86/kernel/hw_breakpoint.c | 9 +++++++++
2 files changed, 11 insertions(+)
diff --git a/arch/x86/include/asm/hw_breakpoint.h b/arch/x86/include/asm/hw_breakpoint.h
index aa6adac6c3a2..c22cc4e87fc5 100644
--- a/arch/x86/include/asm/hw_breakpoint.h
+++ b/arch/x86/include/asm/hw_breakpoint.h
@@ -21,6 +21,7 @@ struct arch_hw_breakpoint {
enum bp_slot_action {
BP_SLOT_ACTION_INSTALL,
+ BP_SLOT_ACTION_REINSTALL,
BP_SLOT_ACTION_UNINSTALL,
};
@@ -65,6 +66,7 @@ extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
int arch_install_hw_breakpoint(struct perf_event *bp);
+int arch_reinstall_hw_breakpoint(struct perf_event *bp);
void arch_uninstall_hw_breakpoint(struct perf_event *bp);
void hw_breakpoint_pmu_read(struct perf_event *bp);
void hw_breakpoint_pmu_unthrottle(struct perf_event *bp);
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 3658ace4bd8d..29c9369264d4 100644
--- a/arch/x86/kernel/hw_breakpoint.c
+++ b/arch/x86/kernel/hw_breakpoint.c
@@ -99,6 +99,10 @@ static int manage_bp_slot(struct perf_event *bp, enum bp_slot_action action)
old_bp = NULL;
new_bp = bp;
break;
+ case BP_SLOT_ACTION_REINSTALL:
+ old_bp = bp;
+ new_bp = bp;
+ break;
case BP_SLOT_ACTION_UNINSTALL:
old_bp = bp;
new_bp = NULL;
@@ -187,6 +191,11 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
return arch_manage_bp(bp, BP_SLOT_ACTION_INSTALL);
}
+int arch_reinstall_hw_breakpoint(struct perf_event *bp)
+{
+ return arch_manage_bp(bp, BP_SLOT_ACTION_REINSTALL);
+}
+
void arch_uninstall_hw_breakpoint(struct perf_event *bp)
{
arch_manage_bp(bp, BP_SLOT_ACTION_UNINSTALL);
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 4/8] HWBP: Add modify_wide_hw_breakpoint_local() API
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
` (2 preceding siblings ...)
2025-09-23 1:17 ` [PATCH v5 3/8] x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 5/8] tracing: wprobe: Add wprobe event trigger Masami Hiramatsu (Google)
` (3 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add modify_wide_hw_breakpoint_local() arch-wide interface which allows
hwbp users to update watch address on-line. This is available if the
arch supports CONFIG_HAVE_REINSTALL_HW_BREAKPOINT.
Note that this allows to change the type only for compatible types,
because it does not release and reserve the hwbp slot based on type.
For instance, you can not change HW_BREAKPOINT_W to HW_BREAKPOINT_X.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v4:
- Update kerneldoc comment about modify_wide_hw_breakpoint_local
according to Randy's comment.
Changes in v2:
- Check type compatibility by checking slot. (Thanks Jinchao!)
---
arch/Kconfig | 10 ++++++++++
arch/x86/Kconfig | 1 +
include/linux/hw_breakpoint.h | 6 ++++++
kernel/events/hw_breakpoint.c | 37 +++++++++++++++++++++++++++++++++++++
4 files changed, 54 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index d1b4ffd6e085..e4787fc814df 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -418,6 +418,16 @@ config HAVE_MIXED_BREAKPOINTS_REGS
Select this option if your arch implements breakpoints under the
latter fashion.
+config HAVE_REINSTALL_HW_BREAKPOINT
+ bool
+ depends on HAVE_HW_BREAKPOINT
+ help
+ Depending on the arch implementation of hardware breakpoints,
+ some of them are able to update the breakpoint configuration
+ without release and reserve the hardware breakpoint register.
+ What configuration is able to update depends on hardware and
+ software implementation.
+
config HAVE_USER_RETURN_NOTIFIER
bool
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 58d890fe2100..49d4ce2af94c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -247,6 +247,7 @@ config X86
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
select HAVE_HW_BREAKPOINT
+ select HAVE_REINSTALL_HW_BREAKPOINT
select HAVE_IOREMAP_PROT
select HAVE_IRQ_EXIT_ON_IRQ_STACK if X86_64
select HAVE_IRQ_TIME_ACCOUNTING
diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index db199d653dd1..ea373f2587f8 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -81,6 +81,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
void *context);
+extern int modify_wide_hw_breakpoint_local(struct perf_event *bp,
+ struct perf_event_attr *attr);
+
extern int register_perf_hw_breakpoint(struct perf_event *bp);
extern void unregister_hw_breakpoint(struct perf_event *bp);
extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events);
@@ -124,6 +127,9 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
void *context) { return NULL; }
static inline int
+modify_wide_hw_breakpoint_local(struct perf_event *bp,
+ struct perf_event_attr *attr) { return -ENOSYS; }
+static inline int
register_perf_hw_breakpoint(struct perf_event *bp) { return -ENOSYS; }
static inline void unregister_hw_breakpoint(struct perf_event *bp) { }
static inline void
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 8ec2cb688903..5ee1522a99c9 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -887,6 +887,43 @@ void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
}
EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
+/**
+ * modify_wide_hw_breakpoint_local - update breakpoint config for local CPU
+ * @bp: the hwbp perf event for this CPU
+ * @attr: the new attribute for @bp
+ *
+ * This does not release and reserve the slot of a HWBP; it just reuses the
+ * current slot on local CPU. So the users must update the other CPUs by
+ * themselves.
+ * Also, since this does not release/reserve the slot, this can not change the
+ * type to incompatible type of the HWBP.
+ * Return err if attr is invalid or the CPU fails to update debug register
+ * for new @attr.
+ */
+#ifdef CONFIG_HAVE_REINSTALL_HW_BREAKPOINT
+int modify_wide_hw_breakpoint_local(struct perf_event *bp,
+ struct perf_event_attr *attr)
+{
+ int ret;
+
+ if (find_slot_idx(bp->attr.bp_type) != find_slot_idx(attr->bp_type))
+ return -EINVAL;
+
+ ret = hw_breakpoint_arch_parse(bp, attr, counter_arch_bp(bp));
+ if (ret)
+ return ret;
+
+ return arch_reinstall_hw_breakpoint(bp);
+}
+#else
+int modify_wide_hw_breakpoint_local(struct perf_event *bp,
+ struct perf_event_attr *attr)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+EXPORT_SYMBOL_GPL(modify_wide_hw_breakpoint_local);
+
/**
* hw_breakpoint_is_used - check if breakpoints are currently used
*
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 5/8] tracing: wprobe: Add wprobe event trigger
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
` (3 preceding siblings ...)
2025-09-23 1:17 ` [PATCH v5 4/8] HWBP: Add modify_wide_hw_breakpoint_local() API Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 6/8] selftests: tracing: Add a basic testcase for wprobe Masami Hiramatsu (Google)
` (2 subsequent siblings)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add wprobe event trigger to set and clear the watch event dynamically.
This allows us to set an watchpoint on a given local variables and
a slab object instead of static objects.
The trigger syntax is below:
- set_wprobe:WPROBE:FIELD[+OFFSET] [if FILTER]
- clear_wprobe:WPROBE[:FIELD[+OFFSET]] [if FILTER]
set_wprobe sets the address pointed by FIELD[+offset] to the WPROBE
event. The FIELD is the field name of trigger event.
clear_wprobe clears the watch address of WPROBE event. If the FIELD
option is specified, it clears only if the current watch address is
same as the given FIELD[+OFFSET] value.
The set_wprobe trigger does not change the type and length, these
must be set when creating a new wprobe.
Also, the WPROBE event must be disabled when setting the new trigger
and it will be busy afterwards. Recommended usage is to add a new
wprobe at NULL address and keep disabled.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v5:
- Following the suggestions, the documentation was revised to suit rst.
Changes in v3:
- Add FIELD option support for clear_wprobe and update document.
- Fix to unregister/free event_trigger_data on file correctly.
- Fix syntax comments.
Changes in v2:
- Getting local cpu perf_event from trace_wprobe directly.
- Remove trace_wprobe_local_perf() because it is conditionally unused.
- Make CONFIG_WPROBE_TRIGGERS a hidden config.
---
Documentation/trace/wprobetrace.rst | 86 +++++++
include/linux/trace_events.h | 1
kernel/trace/Kconfig | 10 +
kernel/trace/trace_wprobe.c | 430 +++++++++++++++++++++++++++++++++++
4 files changed, 527 insertions(+)
diff --git a/Documentation/trace/wprobetrace.rst b/Documentation/trace/wprobetrace.rst
index 025b4c39b809..e3e82c617218 100644
--- a/Documentation/trace/wprobetrace.rst
+++ b/Documentation/trace/wprobetrace.rst
@@ -67,3 +67,89 @@ Here is an example to add a wprobe event on a variable `jiffies`.
<idle>-0 [000] d.Z1. 717.026373: my_jiffies: (tick_do_update_jiffies64+0xbe/0x130)
You can see the code which writes to `jiffies` is `tick_do_update_jiffies64()`.
+
+Combination with trigger action
+-------------------------------
+The event trigger action can extend the utilization of this wprobe.
+
+- set_wprobe:WPEVENT:FIELD[+|-ADJUST]
+- clear_wprobe:WPEVENT[:FIELD[+|-]ADJUST]
+
+Set these triggers to the target event, then the WPROBE event will be
+setup to trace the memory access at FIELD[+|-ADJUST] address.
+When clear_wprobe is hit, if FIELD is NOT specified, the WPEVENT is
+forcibly cleared. If FIELD[[+|-]ADJUST] is set, it clears WPEVENT only
+if its watching address is the same as the FIELD[[+|-]ADJUST] value.
+
+Notes:
+The set_wprobe trigger does not change the type and length, these
+must be set when creating a new wprobe.
+
+The WPROBE event must be disabled when setting the new trigger
+and it will be busy afterwards. Recommended usage is to add a new
+wprobe at NULL address and keep disabled.
+
+
+For example, trace the first 8 bytes of the dentry data structure passed
+to do_truncate() until it is deleted by __dentry_kill().
+(Note: all tracefs setup uses '>>' so that it does not kick do_truncate())
+::
+
+ # echo 'w:watch rw@0:8 address=$addr value=+0($addr)' >> dynamic_events
+ # echo 'f:truncate do_truncate dentry=$arg2' >> dynamic_events
+ # echo 'set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
+ # echo 'f:dentry_kill __dentry_kill dentry=$arg1' >> dynamic_events
+ # echo 'clear_wprobe:watch:dentry' >> events/fprobes/dentry_kill/trigger
+ # echo 1 >> events/fprobes/truncate/enable
+ # echo 1 >> events/fprobes/dentry_kill/enable
+
+ # echo aaa > /tmp/hoge
+ # echo bbb > /tmp/hoge
+ # echo ccc > /tmp/hoge
+ # rm /tmp/hoge
+
+Then, the trace data will show::
+
+ # tracer: nop
+ #
+ # entries-in-buffer/entries-written: 16/16 #P:8
+ #
+ # _-----=> irqs-off/BH-disabled
+ # / _----=> need-resched
+ # | / _---=> hardirq/softirq
+ # || / _--=> preempt-depth
+ # ||| / _-=> migrate-disable
+ # |||| / delay
+ # TASK-PID CPU# ||||| TIMESTAMP FUNCTION
+ # | | | ||||| | |
+ sh-113 [004] ..... 6.467444: truncate: (do_truncate+0x4/0x120) dentry=0xffff8880044f0fd8
+ sh-113 [004] ..Zff 6.468534: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080
+ sh-113 [004] ..Zff 6.468542: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080
+ sh-113 [004] ..Zff 6.468547: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080
+ sh-113 [004] ..Zff 6.468553: watch: (path_openat+0xb3a/0xe70) address=0xffff8880044f0fd8 value=0x200080
+ sh-113 [004] ..Zff 6.468557: watch: (path_openat+0xb9a/0xe70) address=0xffff8880044f0fd8 value=0x200080
+ sh-113 [004] ..... 6.468563: truncate: (do_truncate+0x4/0x120) dentry=0xffff8880044f0fd8
+ sh-113 [004] ...1. 6.469826: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0ea0
+ sh-113 [004] ...1. 6.469859: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0d68
+ rm-118 [001] ..Zff 6.472360: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472366: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472370: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472386: watch: (lookup_fast+0xaa/0x150) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472390: watch: (step_into+0x82/0x360) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472394: watch: (step_into+0x9f/0x360) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472415: watch: (lookup_one_qstr_excl+0x2c/0x150) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472419: watch: (lookup_one_qstr_excl+0xd5/0x150) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472424: watch: (may_delete+0x18/0x200) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472428: watch: (may_delete+0x194/0x200) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] ..Zff 6.472446: watch: (vfs_unlink+0x63/0x1c0) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] d.Z.. 6.472528: watch: (dont_mount+0x19/0x30) address=0xffff8880044f0fd8 value=0x200180
+ rm-118 [001] ..Zff 6.472533: watch: (vfs_unlink+0x11a/0x1c0) address=0xffff8880044f0fd8 value=0x200180
+ rm-118 [001] ..Zff 6.472538: watch: (vfs_unlink+0x12e/0x1c0) address=0xffff8880044f0fd8 value=0x200180
+ rm-118 [001] d.Z1. 6.472543: watch: (d_delete+0x61/0xa0) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] d.Z1. 6.472547: watch: (dentry_unlink_inode+0x14/0x110) address=0xffff8880044f0fd8 value=0x200080
+ rm-118 [001] d.Z1. 6.472551: watch: (dentry_unlink_inode+0x1e/0x110) address=0xffff8880044f0fd8 value=0x80
+ rm-118 [001] d.Z.. 6.472563: watch: (fast_dput+0x8d/0x120) address=0xffff8880044f0fd8 value=0x80
+ rm-118 [001] ...1. 6.472567: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff8880044f0fd8
+ sh-113 [004] ...2. 6.473049: dentry_kill: (__dentry_kill+0x0/0x220) dentry=0xffff888006e383a8
+
+You can see the watch event is correctly configured on the dentry.
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 7c65f2f73ff4..6517c5d7e03e 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -720,6 +720,7 @@ enum event_trigger_type {
ETT_EVENT_HIST = (1 << 4),
ETT_HIST_ENABLE = (1 << 5),
ETT_EVENT_EPROBE = (1 << 6),
+ ETT_EVENT_WPROBE = (1 << 7),
};
extern int filter_match_preds(struct event_filter *filter, void *rec);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 27adf6a9ff32..e9bd6dd1ae8e 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -820,6 +820,16 @@ config WPROBE_EVENTS
Those events can be inserted wherever hardware breakpoints can be
set, and record accessed memory address and values.
+config WPROBE_TRIGGERS
+ depends on WPROBE_EVENTS
+ depends on HAVE_REINSTALL_HW_BREAKPOINT
+ bool
+ default y
+ help
+ This adds an event trigger which will set the wprobe on a specific
+ field of an event. This allows user to trace the memory access of
+ an address pointed by the event field.
+
config BPF_EVENTS
depends on BPF_SYSCALL
depends on (KPROBE_EVENTS || UPROBE_EVENTS) && PERF_EVENTS
diff --git a/kernel/trace/trace_wprobe.c b/kernel/trace/trace_wprobe.c
index 4b00a8e917c1..84b6c93a18e0 100644
--- a/kernel/trace/trace_wprobe.c
+++ b/kernel/trace/trace_wprobe.c
@@ -6,6 +6,8 @@
*/
#define pr_fmt(fmt) "trace_wprobe: " fmt
+#include <linux/atomic.h>
+#include <linux/errno.h>
#include <linux/hw_breakpoint.h>
#include <linux/kallsyms.h>
#include <linux/list.h>
@@ -14,11 +16,14 @@
#include <linux/perf_event.h>
#include <linux/rculist.h>
#include <linux/security.h>
+#include <linux/spinlock.h>
#include <linux/tracepoint.h>
#include <linux/uaccess.h>
+#include <linux/workqueue.h>
#include <asm/ptrace.h>
+#include "trace.h"
#include "trace_dynevent.h"
#include "trace_probe.h"
#include "trace_probe_kernel.h"
@@ -683,3 +688,428 @@ static __init int init_wprobe_trace(void)
}
fs_initcall(init_wprobe_trace);
+#ifdef CONFIG_WPROBE_TRIGGERS
+
+static int wprobe_trigger_global_enabled;
+
+#define SET_WPROBE_STR "set_wprobe"
+#define CLEAR_WPROBE_STR "clear_wprobe"
+#define WPROBE_DEFAULT_CLEAR_ADDRESS ((unsigned long)&wprobe_trigger_global_enabled)
+
+struct wprobe_trigger_data {
+ struct trace_event_file *file;
+ struct trace_wprobe *tw;
+
+ struct perf_event_attr attr;
+ raw_spinlock_t lock; /* lock protects attr */
+ struct work_struct work;// TBD: use work + IPI or use sched/raw_syscall event?
+ unsigned int offset;
+ long adjust;
+ const char *field;
+ // size must be unsigned long because it should be an address.
+ bool clear;
+};
+
+static int trace_wprobe_update_local(struct trace_wprobe *tw,
+ struct perf_event_attr *attr)
+{
+ struct perf_event *bp = *this_cpu_ptr(tw->bp_event);
+
+ return modify_wide_hw_breakpoint_local(bp, attr);
+}
+
+static void wprobe_smp_update_func(void *data)
+{
+ struct wprobe_trigger_data *trigger_data = data;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&trigger_data->lock, flags);
+ trace_wprobe_update_local(trigger_data->tw, &trigger_data->attr);
+ raw_spin_unlock_irqrestore(&trigger_data->lock, flags);
+}
+
+static void wprobe_work_func(struct work_struct *work)
+{
+ struct wprobe_trigger_data *data = container_of(work, struct wprobe_trigger_data, work);
+
+ on_each_cpu(wprobe_smp_update_func, data, false);
+}
+
+static void wprobe_trigger(struct event_trigger_data *data,
+ struct trace_buffer *buffer, void *rec,
+ struct ring_buffer_event *event)
+{
+ struct wprobe_trigger_data *wprobe_data = data->private_data;
+ struct perf_event_attr *attr = &wprobe_data->attr;
+ struct trace_wprobe *tw = wprobe_data->tw;
+ unsigned long addr, flags;
+ int ret = -EBUSY;
+
+ addr = *(unsigned long *)(rec + wprobe_data->offset);
+ addr += wprobe_data->adjust;
+
+ raw_spin_lock_irqsave(&wprobe_data->lock, flags);
+
+ if (!wprobe_data->clear) {
+ if (tw->addr != WPROBE_DEFAULT_CLEAR_ADDRESS)
+ goto unlock;
+
+ tw->addr = attr->bp_addr = addr;
+ ret = trace_wprobe_update_local(tw, attr);
+ if (WARN_ON_ONCE(ret))
+ goto unlock;
+ clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &wprobe_data->file->flags);
+ } else {
+ if (tw->addr == WPROBE_DEFAULT_CLEAR_ADDRESS)
+ goto unlock;
+ if (wprobe_data->field && tw->addr != addr)
+ goto unlock;
+
+ tw->addr = attr->bp_addr = WPROBE_DEFAULT_CLEAR_ADDRESS;
+ ret = trace_wprobe_update_local(tw, attr);
+ if (WARN_ON_ONCE(ret))
+ goto unlock;
+ set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &wprobe_data->file->flags);
+ }
+ schedule_work(&wprobe_data->work);
+unlock:
+ raw_spin_unlock_irqrestore(&wprobe_data->lock, flags);
+}
+
+static void free_wprobe_trigger_data(struct wprobe_trigger_data *wprobe_data)
+{
+ if (wprobe_data)
+ kfree(wprobe_data->field);
+ kfree(wprobe_data);
+}
+
+DEFINE_FREE(free_wprobe_trigger_data, struct wprobe_trigger_data *, free_wprobe_trigger_data(_T));
+
+static int wprobe_trigger_print(struct seq_file *m,
+ struct event_trigger_data *data)
+{
+ struct wprobe_trigger_data *wprobe_data = data->private_data;
+
+ if (wprobe_data->clear) {
+ seq_printf(m, "%s:%s", CLEAR_WPROBE_STR,
+ trace_event_name(wprobe_data->file->event_call));
+ if (wprobe_data->field) {
+ seq_printf(m, ":%s%+ld",
+ wprobe_data->field, wprobe_data->adjust);
+ }
+ } else
+ seq_printf(m, "%s:%s:%s%+ld", SET_WPROBE_STR,
+ trace_event_name(wprobe_data->file->event_call),
+ wprobe_data->field, wprobe_data->adjust);
+
+ if (data->filter_str)
+ seq_printf(m, " if %s\n", data->filter_str);
+ else
+ seq_putc(m, '\n');
+
+ return 0;
+}
+
+static struct wprobe_trigger_data *
+wprobe_trigger_alloc(struct trace_wprobe *tw, struct trace_event_file *file,
+ bool clear)
+{
+ struct wprobe_trigger_data *wprobe_data;
+ struct perf_event_attr *attr;
+
+ wprobe_data = kzalloc(sizeof(*wprobe_data), GFP_KERNEL);
+ if (!wprobe_data)
+ return NULL;
+
+ wprobe_data->tw = tw;
+ wprobe_data->clear = clear;
+ wprobe_data->file = file;
+
+ attr = &wprobe_data->attr;
+ hw_breakpoint_init(attr);
+ attr->bp_type = tw->type;
+ attr->bp_addr = WPROBE_DEFAULT_CLEAR_ADDRESS;
+ attr->bp_len = tw->len;
+
+ raw_spin_lock_init(&wprobe_data->lock);
+ INIT_WORK(&wprobe_data->work, wprobe_work_func);
+
+ return wprobe_data;
+}
+
+static void wprobe_trigger_free(struct event_trigger_data *data)
+{
+ struct wprobe_trigger_data *wprobe_data = data->private_data;
+
+ if (WARN_ON_ONCE(data->ref <= 0))
+ return;
+
+ data->ref--;
+ if (!data->ref) {
+ /* Remove the SOFT_MODE flag */
+ trace_event_enable_disable(wprobe_data->file, 0, 1);
+ trace_event_put_ref(wprobe_data->file->event_call);
+ trigger_data_free(data);
+ free_wprobe_trigger_data(wprobe_data);
+ }
+}
+
+static const struct event_trigger_ops set_wprobe_trigger_ops = {
+ .trigger = wprobe_trigger,
+ .print = wprobe_trigger_print,
+ .init = event_trigger_init,
+ .free = wprobe_trigger_free,
+};
+
+static const struct event_trigger_ops clear_wprobe_trigger_ops = {
+ .trigger = wprobe_trigger,
+ .print = wprobe_trigger_print,
+ .init = event_trigger_init,
+ .free = wprobe_trigger_free,
+};
+
+static int wprobe_trigger_cmd_parse(struct event_command *cmd_ops,
+ struct trace_event_file *file,
+ char *glob, char *cmd,
+ char *param_and_filter)
+{
+ /*
+ * set_wprobe:EVENT:FIELD[+OFFS]
+ * clear_wprobe:EVENT[:FIELD[+OFFS]]
+ */
+ struct wprobe_trigger_data *wprobe_data __free(free_wprobe_trigger_data) = NULL;
+ struct event_trigger_data *trigger_data __free(kfree) = NULL;
+ struct ftrace_event_field *field = NULL;
+ struct trace_event_file *wprobe_file;
+ struct trace_array *tr = file->tr;
+ struct trace_event_call *event;
+ struct perf_event_attr *attr;
+ char *event_str, *field_str;
+ bool remove, clear = false;
+ struct trace_wprobe *tw;
+ char *param, *filter;
+ int ret;
+
+ remove = event_trigger_check_remove(glob);
+
+ if (!strcmp(cmd, CLEAR_WPROBE_STR))
+ clear = true;
+
+ if (event_trigger_empty_param(param_and_filter))
+ return -EINVAL;
+
+ ret = event_trigger_separate_filter(param_and_filter, ¶m, &filter, true);
+ if (ret)
+ return ret;
+
+ event_str = strsep(¶m, ":");
+
+ /* Find target wprobe */
+ tw = find_trace_wprobe(event_str, WPROBE_EVENT_SYSTEM);
+ if (!tw)
+ return -ENOENT;
+ /* The target wprobe must not be used (unless clear) */
+ if (!remove && !clear && trace_probe_is_enabled(&tw->tp))
+ return -EBUSY;
+
+ wprobe_file = find_event_file(tr, WPROBE_EVENT_SYSTEM, event_str);
+ if (!wprobe_file)
+ return -EINVAL;
+
+ wprobe_data = wprobe_trigger_alloc(tw, wprobe_file, clear);
+ if (!wprobe_data)
+ return -ENOMEM;
+ attr = &wprobe_data->attr;
+
+ /* Find target field, which must be equivarent to "void *" */
+ field_str = strsep(¶m, ":");
+ /* trigger removing or clear_wprobe does not need field. */
+ if (!remove && !clear && !field_str)
+ return -EINVAL;
+
+ if (field_str) {
+ char *offs;
+
+ offs = strpbrk(field_str, "+-");
+ if (offs) {
+ long val;
+
+ if (kstrtol(offs, 0, &val) < 0)
+ return -EINVAL;
+ wprobe_data->adjust = val;
+ *offs = '\0';
+ }
+
+ event = file->event_call;
+ field = trace_find_event_field(event, field_str);
+ if (!field)
+ return -ENOENT;
+
+ if (field->size != sizeof(void *))
+ return -ENOEXEC;
+ wprobe_data->offset = field->offset;
+ wprobe_data->field = kstrdup(field_str, GFP_KERNEL);
+ if (!wprobe_data->field)
+ return -ENOMEM;
+ }
+
+ trigger_data = trigger_data_alloc(cmd_ops, cmd, param, wprobe_data);
+ if (!trigger_data)
+ return -ENOMEM;
+
+ /* Up the trigger_data count to make sure nothing frees it on failure */
+ event_trigger_init(trigger_data);
+
+ if (remove) {
+ event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
+ return 0;
+ }
+
+ ret = event_trigger_parse_num(param, trigger_data);
+ if (ret)
+ return ret;
+
+ ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
+ if (ret < 0)
+ return ret;
+
+ /* Soft-enable (register) wprobe event on WPROBE_DEFAULT_CLEAR_ADDRESS */
+ tw->addr = attr->bp_addr = WPROBE_DEFAULT_CLEAR_ADDRESS;
+ ret = trace_event_enable_disable(wprobe_file, 1, 1);
+ if (ret < 0) {
+ event_trigger_reset_filter(cmd_ops, trigger_data);
+ return ret;
+ }
+ ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
+ if (ret) {
+ event_trigger_reset_filter(cmd_ops, trigger_data);
+ trace_event_enable_disable(wprobe_file, 0, 1);
+ return ret;
+ }
+ /* Make it NULL to avoid freeing trigger_data and wprobe_data by __free() */
+ trigger_data = NULL;
+ wprobe_data = NULL;
+
+ return 0;
+}
+
+/* Return event_trigger_data if there is a trigger which points the same wprobe */
+static struct event_trigger_data *
+wprobe_trigger_find_same(struct event_trigger_data *test,
+ struct trace_event_file *file)
+{
+ struct wprobe_trigger_data *test_wprobe_data = test->private_data;
+ struct wprobe_trigger_data *wprobe_data;
+ struct event_trigger_data *iter;
+
+ list_for_each_entry(iter, &file->triggers, list) {
+ wprobe_data = iter->private_data;
+ if (!wprobe_data ||
+ iter->cmd_ops->trigger_type !=
+ test->cmd_ops->trigger_type)
+ continue;
+ if (wprobe_data->tw == test_wprobe_data->tw)
+ return iter;
+ }
+ return NULL;
+}
+
+static int wprobe_register_trigger(char *glob,
+ struct event_trigger_data *data,
+ struct trace_event_file *file)
+{
+ int ret = 0;
+
+ lockdep_assert_held(&event_mutex);
+
+ /* The same wprobe is not accept on the same file (event) */
+ if (wprobe_trigger_find_same(data, file))
+ return -EEXIST;
+
+ if (data->ops->init) {
+ ret = data->ops->init(data);
+ if (ret < 0)
+ return ret;
+ }
+
+ list_add_rcu(&data->list, &file->triggers);
+
+ update_cond_flag(file);
+ ret = trace_event_trigger_enable_disable(file, 1);
+ if (ret < 0) {
+ list_del_rcu(&data->list);
+ update_cond_flag(file);
+ }
+ return ret;
+}
+
+static void wprobe_unregister_trigger(char *glob,
+ struct event_trigger_data *test,
+ struct trace_event_file *file)
+{
+ struct event_trigger_data *data;
+
+ lockdep_assert_held(&event_mutex);
+
+ data = wprobe_trigger_find_same(test, file);
+ if (!data)
+ return;
+
+ list_del_rcu(&data->list);
+ trace_event_trigger_enable_disable(file, 0);
+ update_cond_flag(file);
+ if (data->ops->free)
+ data->ops->free(data);
+}
+
+static const struct event_trigger_ops *
+wprobe_get_trigger_ops(char *cmd, char *param)
+{
+ if (!strcmp(cmd, SET_WPROBE_STR))
+ return &set_wprobe_trigger_ops;
+
+ return &clear_wprobe_trigger_ops;
+}
+
+static struct event_command trigger_wprobe_set_cmd = {
+ .name = SET_WPROBE_STR,
+ .trigger_type = ETT_EVENT_WPROBE,
+ /* This triggers after when the event is recorded. */
+ .flags = EVENT_CMD_FL_NEEDS_REC,
+ .parse = wprobe_trigger_cmd_parse,
+ .reg = wprobe_register_trigger,
+ .unreg = wprobe_unregister_trigger,
+ .get_trigger_ops = wprobe_get_trigger_ops,
+ .set_filter = set_trigger_filter,
+};
+
+static struct event_command trigger_wprobe_clear_cmd = {
+ .name = CLEAR_WPROBE_STR,
+ .trigger_type = ETT_EVENT_WPROBE,
+ /* This triggers after when the event is recorded. */
+ .flags = EVENT_CMD_FL_NEEDS_REC,
+ .parse = wprobe_trigger_cmd_parse,
+ .reg = wprobe_register_trigger,
+ .unreg = wprobe_unregister_trigger,
+ .get_trigger_ops = wprobe_get_trigger_ops,
+ .set_filter = set_trigger_filter,
+};
+
+static __init int init_trigger_wprobe_cmds(void)
+{
+ int ret;
+
+ ret = register_event_command(&trigger_wprobe_set_cmd);
+ if (WARN_ON(ret < 0))
+ return ret;
+ ret = register_event_command(&trigger_wprobe_clear_cmd);
+ if (WARN_ON(ret < 0))
+ unregister_event_command(&trigger_wprobe_set_cmd);
+
+ if (!ret)
+ wprobe_trigger_global_enabled = 1;
+
+ return ret;
+}
+fs_initcall(init_trigger_wprobe_cmds);
+#endif /* CONFIG_WPROBE_TRIGGERS */
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 6/8] selftests: tracing: Add a basic testcase for wprobe
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
` (4 preceding siblings ...)
2025-09-23 1:17 ` [PATCH v5 5/8] tracing: wprobe: Add wprobe event trigger Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:17 ` [PATCH v5 7/8] selftests: tracing: Add syntax " Masami Hiramatsu (Google)
2025-09-23 1:18 ` [PATCH v5 8/8] selftests: ftrace: Add wprobe trigger testcase Masami Hiramatsu (Google)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add 'add_remove_wprobe.tc' testcase for testing wprobe event that
tests adding and removing operations of the wprobe event.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v5:
- Enable CONFIG_WPROBE_EVENTS in config for ftrace selftest
---
tools/testing/selftests/ftrace/config | 1
.../ftrace/test.d/dynevent/add_remove_wprobe.tc | 68 ++++++++++++++++++++
2 files changed, 69 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc
diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftests/ftrace/config
index 544de0db5f58..d2f503722020 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -27,3 +27,4 @@ CONFIG_STACK_TRACER=y
CONFIG_TRACER_SNAPSHOT=y
CONFIG_UPROBES=y
CONFIG_UPROBE_EVENTS=y
+CONFIG_WPROBE_EVENTS=y
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc
new file mode 100644
index 000000000000..20774c7f69f8
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_wprobe.tc
@@ -0,0 +1,68 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Generic dynamic event - add/remove wprobe events
+# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README
+
+echo 0 > events/enable
+echo > dynamic_events
+
+# Use jiffies as a variable that is frequently written to.
+TARGET=jiffies
+
+echo "w:my_wprobe w@$TARGET" >> dynamic_events
+
+grep -q my_wprobe dynamic_events
+if [ $? -ne 0 ]; then
+ echo "Failed to create wprobe event"
+ exit_fail
+fi
+
+test -d events/wprobes/my_wprobe
+if [ $? -ne 0 ]; then
+ echo "Failed to create wprobe event directory"
+ exit_fail
+fi
+
+echo 1 > events/wprobes/my_wprobe/enable
+
+# Check if the event is enabled
+cat events/wprobes/my_wprobe/enable | grep -q 1
+if [ $? -ne 0 ]; then
+ echo "Failed to enable wprobe event"
+ exit_fail
+fi
+
+# Let some time pass to trigger the breakpoint
+sleep 1
+
+# Check if we got any trace output
+if !grep -q my_wprobe trace; then
+ echo "wprobe event was not triggered"
+fi
+
+echo 0 > events/wprobes/my_wprobe/enable
+
+# Check if the event is disabled
+cat events/wprobes/my_wprobe/enable | grep -q 0
+if [ $? -ne 0 ]; then
+ echo "Failed to disable wprobe event"
+ exit_fail
+fi
+
+echo "-:my_wprobe" >> dynamic_events
+
+! grep -q my_wprobe dynamic_events
+if [ $? -ne 0 ]; then
+ echo "Failed to remove wprobe event"
+ exit_fail
+fi
+
+! test -d events/wprobes/my_wprobe
+if [ $? -ne 0 ]; then
+ echo "Failed to remove wprobe event directory"
+ exit_fail
+fi
+
+clear_trace
+
+exit 0
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 7/8] selftests: tracing: Add syntax testcase for wprobe
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
` (5 preceding siblings ...)
2025-09-23 1:17 ` [PATCH v5 6/8] selftests: tracing: Add a basic testcase for wprobe Masami Hiramatsu (Google)
@ 2025-09-23 1:17 ` Masami Hiramatsu (Google)
2025-09-23 1:18 ` [PATCH v5 8/8] selftests: ftrace: Add wprobe trigger testcase Masami Hiramatsu (Google)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:17 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add "wprobe_syntax_errors.tc" testcase for testing syntax errors
of the watch probe events.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Fix to use "wprobe" prefix for detecting error log.
- Fix an error place with wrong offset.
---
.../test.d/dynevent/wprobes_syntax_errors.tc | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.tc
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.tc
new file mode 100644
index 000000000000..56ac579d60ae
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/wprobes_syntax_errors.tc
@@ -0,0 +1,20 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Watch probe event parser error log check
+# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README
+
+check_error() { # command-with-error-pos-by-^
+ ftrace_errlog_check 'wprobe' "$1" 'dynamic_events'
+}
+
+check_error 'w ^symbol' # BAD_ACCESS_FMT
+check_error 'w ^a@symbol' # BAD_ACCESS_TYPE
+check_error 'w w@^symbol' # BAD_ACCESS_ADDR
+check_error 'w w@jiffies^+offset' # BAD_ACCESS_ADDR
+check_error 'w w@jiffies:^100' # BAD_ACCESS_LEN
+check_error 'w w@jiffies ^$arg1' # BAD_VAR
+check_error 'w w@jiffies ^$retval' # BAD_VAR
+check_error 'w w@jiffies ^$stack' # BAD_VAR
+check_error 'w w@jiffies ^%ax' # BAD_VAR
+
+exit 0
^ permalink raw reply related [flat|nested] 10+ messages in thread* [PATCH v5 8/8] selftests: ftrace: Add wprobe trigger testcase
2025-09-23 1:16 [PATCH v5 0/8] tracing: wprobe: Add wprobe for watchpoint Masami Hiramatsu (Google)
` (6 preceding siblings ...)
2025-09-23 1:17 ` [PATCH v5 7/8] selftests: tracing: Add syntax " Masami Hiramatsu (Google)
@ 2025-09-23 1:18 ` Masami Hiramatsu (Google)
7 siblings, 0 replies; 10+ messages in thread
From: Masami Hiramatsu (Google) @ 2025-09-23 1:18 UTC (permalink / raw)
To: Steven Rostedt, Peter Zijlstra, Ingo Molnar, x86
Cc: Jinchao Wang, Mathieu Desnoyers, Masami Hiramatsu,
Thomas Gleixner, Borislav Petkov, Dave Hansen, H . Peter Anvin,
Alexander Shishkin, Ian Rogers, linux-kernel, linux-trace-kernel,
linux-doc, linux-perf-users
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a testcase for checking wprobe trigger. This sets set_wprobe and
clear_wprobe triggers on fprobe events to watch dentry access.
So this depends on both wprobe and fprobe.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v5:
- Enable CONFIG_WPROBE_TRIGGERS in the config for ftrace test.
Changes in v3:
- Newly added.
---
tools/testing/selftests/ftrace/config | 1
.../ftrace/test.d/trigger/trigger-wprobe.tc | 48 ++++++++++++++++++++
2 files changed, 49 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
diff --git a/tools/testing/selftests/ftrace/config b/tools/testing/selftests/ftrace/config
index d2f503722020..ecdee77f360f 100644
--- a/tools/testing/selftests/ftrace/config
+++ b/tools/testing/selftests/ftrace/config
@@ -28,3 +28,4 @@ CONFIG_TRACER_SNAPSHOT=y
CONFIG_UPROBES=y
CONFIG_UPROBE_EVENTS=y
CONFIG_WPROBE_EVENTS=y
+CONFIG_WPROBE_TRIGGERS=y
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
new file mode 100644
index 000000000000..a012f7b92405
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-wprobe.tc
@@ -0,0 +1,48 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: event trigger - test wprobe trigger
+# requires: dynamic_events "w[:[<group>/][<event>]] [r|w|rw]@<addr>[:<len>]":README events/sched/sched_process_fork/trigger
+
+echo 0 > tracing_on
+
+:;: "Add a wprobe event used by trigger" ;:
+echo 'w:watch rw@0:8 address=$addr value=+0($addr)' > dynamic_events
+
+:;: "Add events for triggering wprobe" ;:
+echo 'f:truncate do_truncate dentry=$arg2' >> dynamic_events
+echo 'f:dentry_kill __dentry_kill dentry=$arg1' >> dynamic_events
+
+:;: "Add wprobe triggers" ;:
+echo 'set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
+echo 'clear_wprobe:watch:dentry' >> events/fprobes/dentry_kill/trigger
+cat events/fprobes/truncate/trigger | grep ^set_wprobe
+cat events/fprobes/dentry_kill/trigger | grep ^clear_wprobe
+
+:;: "Ensure wprobe is still disabled" ;:
+cat events/wprobes/watch/enable | grep 0
+
+:;: "Enable events for triggers" ;:
+echo 1 >> events/fprobes/truncate/enable
+echo 1 >> events/fprobes/dentry_kill/enable
+
+:;: "Start test workload" ;:
+echo 1 >> tracing_on
+
+echo aaa > /tmp/hoge
+echo bbb > /tmp/hoge
+echo ccc > /tmp/hoge
+rm /tmp/hoge
+
+:;: "Check trace results" ;:
+cat trace | grep watch
+
+:;: "Ensure wprobe becomes disabled again" ;:
+cat events/wprobes/watch/enable | grep 0
+
+:;: "Remove wprobe triggers" ;:
+echo '!set_wprobe:watch:dentry' >> events/fprobes/truncate/trigger
+echo '!clear_wprobe:watch' >> events/fprobes/dentry_kill/trigger
+! grep ^set_wprobe events/fprobes/truncate/trigger
+! grep ^clear_wprobe events/fprobes/dentry_kill/trigger
+
+exit 0
\ No newline at end of file
^ permalink raw reply related [flat|nested] 10+ messages in thread