[RFC PATCH v2 4/6] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS

From: Masami Hiramatsu (Google)
Date: Mon Aug 07 2023 - 02:49:37 EST

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From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Allow fprobe events to be enabled with CONFIG_DYNAMIC_FTRACE_WITH_ARGS.
With this change, fprobe events mostly use ftrace_regs instead of pt_regs.
Note that if the arch doesn't enable HAVE_PT_REGS_COMPAT_FTRACE_REGS,
fprobe events will not be able to use from perf.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
---
kernel/trace/Kconfig | 1 -
kernel/trace/trace_fprobe.c | 72 ++++++++++++++++++++++-----------------
kernel/trace/trace_probe_tmpl.h | 2 +
3 files changed, 41 insertions(+), 34 deletions(-)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 7d6abb5bd861..e9b7bd88cf9e 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -679,7 +679,6 @@ config FPROBE_EVENTS
select TRACING
select PROBE_EVENTS
select DYNAMIC_EVENTS
- depends on DYNAMIC_FTRACE_WITH_REGS
default y
help
This allows user to add tracing events on the function entry and
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index f440c97e050f..4e9c250dbd19 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -132,25 +132,30 @@ static int
process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
void *base)
{
- struct pt_regs *regs = rec;
- unsigned long val;
+ struct ftrace_regs *fregs = rec;
+ unsigned long val, *stackp;
int ret;

retry:
/* 1st stage: get value from context */
switch (code->op) {
case FETCH_OP_STACK:
- val = regs_get_kernel_stack_nth(regs, code->param);
+ stackp = (unsigned long *)ftrace_regs_get_stack_pointer(fregs);
+ if (((unsigned long)(stackp + code->param) & ~(THREAD_SIZE - 1)) ==
+ ((unsigned long)stackp & ~(THREAD_SIZE - 1)))
+ val = *(stackp + code->param);
+ else
+ val = 0;
break;
case FETCH_OP_STACKP:
- val = kernel_stack_pointer(regs);
+ val = ftrace_regs_get_stack_pointer(fregs);
break;
case FETCH_OP_RETVAL:
- val = regs_return_value(regs);
+ val = ftrace_regs_return_value(fregs);
break;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
case FETCH_OP_ARG:
- val = regs_get_kernel_argument(regs, code->param);
+ val = ftrace_regs_get_argument(fregs, code->param);
break;
#endif
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
@@ -170,7 +175,7 @@ NOKPROBE_SYMBOL(process_fetch_insn)
/* function entry handler */
static nokprobe_inline void
__fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs,
+ struct ftrace_regs *fregs,
struct trace_event_file *trace_file)
{
struct fentry_trace_entry_head *entry;
@@ -184,36 +189,36 @@ __fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (trace_trigger_soft_disabled(trace_file))
return;

- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);

entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tf->tp.size + dsize);
if (!entry)
return;

- fbuffer.regs = regs;
+ fbuffer.regs = ftrace_get_regs(fregs);
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
entry->ip = entry_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);

trace_event_buffer_commit(&fbuffer);
}

static void
fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs)
+ struct ftrace_regs *fregs)
{
struct event_file_link *link;

trace_probe_for_each_link_rcu(link, &tf->tp)
- __fentry_trace_func(tf, entry_ip, regs, link->file);
+ __fentry_trace_func(tf, entry_ip, fregs, link->file);
}
NOKPROBE_SYMBOL(fentry_trace_func);

/* Kretprobe handler */
static nokprobe_inline void
__fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
struct trace_event_file *trace_file)
{
struct fexit_trace_entry_head *entry;
@@ -227,37 +232,37 @@ __fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (trace_trigger_soft_disabled(trace_file))
return;

- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);

entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tf->tp.size + dsize);
if (!entry)
return;

- fbuffer.regs = regs;
+ fbuffer.regs = ftrace_get_regs(fregs);
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
entry->func = entry_ip;
entry->ret_ip = ret_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);

trace_event_buffer_commit(&fbuffer);
}

static void
fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs)
+ unsigned long ret_ip, struct ftrace_regs *fregs)
{
struct event_file_link *link;

trace_probe_for_each_link_rcu(link, &tf->tp)
- __fexit_trace_func(tf, entry_ip, ret_ip, regs, link->file);
+ __fexit_trace_func(tf, entry_ip, ret_ip, fregs, link->file);
}
NOKPROBE_SYMBOL(fexit_trace_func);

#ifdef CONFIG_PERF_EVENTS

static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs)
+ struct ftrace_regs *fregs, struct pt_regs *regs)
{
struct trace_event_call *call = trace_probe_event_call(&tf->tp);
struct fentry_trace_entry_head *entry;
@@ -269,7 +274,7 @@ static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (hlist_empty(head))
return 0;

- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
__size = sizeof(*entry) + tf->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
@@ -280,7 +285,7 @@ static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,

entry->ip = entry_ip;
memset(&entry[1], 0, dsize);
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
return 0;
@@ -289,7 +294,8 @@ NOKPROBE_SYMBOL(fentry_perf_func);

static void
fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs)
+ unsigned long ret_ip, struct ftrace_regs *fregs,
+ struct pt_regs *regs)
{
struct trace_event_call *call = trace_probe_event_call(&tf->tp);
struct fexit_trace_entry_head *entry;
@@ -301,7 +307,7 @@ fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (hlist_empty(head))
return;

- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
__size = sizeof(*entry) + tf->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
@@ -312,7 +318,7 @@ fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,

entry->func = entry_ip;
entry->ret_ip = ret_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
}
@@ -327,14 +333,15 @@ static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
struct pt_regs *regs = ftrace_get_regs(fregs);
int ret = 0;

+ if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
+ fentry_trace_func(tf, entry_ip, fregs);
+
+#ifdef CONFIG_PERF_EVENTS
if (!regs)
return 0;

- if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
- fentry_trace_func(tf, entry_ip, regs);
-#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
- ret = fentry_perf_func(tf, entry_ip, regs);
+ ret = fentry_perf_func(tf, entry_ip, fregs, regs);
#endif
return ret;
}
@@ -347,14 +354,15 @@ static void fexit_dispatcher(struct fprobe *fp, unsigned long entry_ip,
struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
struct pt_regs *regs = ftrace_get_regs(fregs);

+ if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
+ fexit_trace_func(tf, entry_ip, ret_ip, fregs);
+
+#ifdef CONFIG_PERF_EVENTS
if (!regs)
return;

- if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
- fexit_trace_func(tf, entry_ip, ret_ip, regs);
-#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
- fexit_perf_func(tf, entry_ip, ret_ip, regs);
+ fexit_perf_func(tf, entry_ip, ret_ip, fregs, regs);
#endif
}
NOKPROBE_SYMBOL(fexit_dispatcher);
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 3935b347f874..05445a745a07 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -232,7 +232,7 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,

/* Sum up total data length for dynamic arrays (strings) */
static nokprobe_inline int
-__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
+__get_data_size(struct trace_probe *tp, void *regs)
{
struct probe_arg *arg;
int i, len, ret = 0;

Next message: Masami Hiramatsu (Google): "[RFC PATCH v2 5/6] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs"
Previous message: Francesco Dolcini: "Re: [PATCH v2 0/4] arm64: dts: ti: Enable Audio on Verdin AM62"
In reply to: Masami Hiramatsu (Google): "[RFC PATCH v2 3/6] fprobe: rethook: Use fprobe_regs in fprobe exit handler and rethook"
Next in thread: Masami Hiramatsu (Google): "[RFC PATCH v2 5/6] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs"
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