x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 605 insertions, 0 deletions

diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c
new file mode 100644
index 000000000..e9a27fa7b
--- /dev/null
+++ b/net/rxrpc/proc.c
@@ -0,0 +1,605 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* /proc/net/ support for AF_RXRPC
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/module.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+#define RXRPC_PROC_ADDRBUF_SIZE \
+	(sizeof("[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255]") + \
+	 sizeof(":12345"))
+
+static const char *const rxrpc_conn_states[RXRPC_CONN__NR_STATES] = {
+	[RXRPC_CONN_UNUSED]			= "Unused  ",
+	[RXRPC_CONN_CLIENT_UNSECURED]		= "ClUnsec ",
+	[RXRPC_CONN_CLIENT]			= "Client  ",
+	[RXRPC_CONN_SERVICE_PREALLOC]		= "SvPrealc",
+	[RXRPC_CONN_SERVICE_UNSECURED]		= "SvUnsec ",
+	[RXRPC_CONN_SERVICE_CHALLENGING]	= "SvChall ",
+	[RXRPC_CONN_SERVICE]			= "SvSecure",
+	[RXRPC_CONN_ABORTED]			= "Aborted ",
+};
+
+/*
+ * generate a list of extant and dead calls in /proc/net/rxrpc_calls
+ */
+static void *rxrpc_call_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rcu)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	rcu_read_lock();
+	return seq_list_start_head_rcu(&rxnet->calls, *_pos);
+}
+
+static void *rxrpc_call_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	return seq_list_next_rcu(v, &rxnet->calls, pos);
+}
+
+static void rxrpc_call_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+static int rxrpc_call_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_local *local;
+	struct rxrpc_call *call;
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	enum rxrpc_call_state state;
+	rxrpc_seq_t tx_bottom;
+	char lbuff[RXRPC_PROC_ADDRBUF_SIZE], rbuff[RXRPC_PROC_ADDRBUF_SIZE];
+	long timeout = 0;
+
+	if (v == &rxnet->calls) {
+		seq_puts(seq,
+			 "Proto Local                                          "
+			 " Remote                                         "
+			 " SvID ConnID   CallID   End Use State    Abort   "
+			 " DebugId  TxSeq    TW RxSeq    RW RxSerial CW RxTimo\n");
+		return 0;
+	}
+
+	call = list_entry(v, struct rxrpc_call, link);
+
+	local = call->local;
+	if (local)
+		scnprintf(lbuff, sizeof(lbuff), "%pISpc", &local->srx.transport);
+	else
+		strcpy(lbuff, "no_local");
+
+	scnprintf(rbuff, sizeof(rbuff), "%pISpc", &call->dest_srx.transport);
+
+	state = rxrpc_call_state(call);
+	if (state != RXRPC_CALL_SERVER_PREALLOC)
+		timeout = ktime_ms_delta(READ_ONCE(call->expect_rx_by), ktime_get_real());
+
+	tx_bottom = READ_ONCE(call->tx_bottom);
+	seq_printf(seq,
+		   "UDP   %-47.47s %-47.47s %4x %08x %08x %s %3u"
+		   " %-8.8s %08x %08x %08x %02x %08x %02x %08x %02x %06lx\n",
+		   lbuff,
+		   rbuff,
+		   call->dest_srx.srx_service,
+		   call->cid,
+		   call->call_id,
+		   rxrpc_is_service_call(call) ? "Svc" : "Clt",
+		   refcount_read(&call->ref),
+		   rxrpc_call_states[state],
+		   call->abort_code,
+		   call->debug_id,
+		   tx_bottom, READ_ONCE(call->tx_top) - tx_bottom,
+		   call->ackr_window, call->ackr_wtop - call->ackr_window,
+		   call->rx_serial,
+		   call->cong_cwnd,
+		   timeout);
+
+	return 0;
+}
+
+const struct seq_operations rxrpc_call_seq_ops = {
+	.start  = rxrpc_call_seq_start,
+	.next   = rxrpc_call_seq_next,
+	.stop   = rxrpc_call_seq_stop,
+	.show   = rxrpc_call_seq_show,
+};
+
+/*
+ * generate a list of extant virtual connections in /proc/net/rxrpc_conns
+ */
+static void *rxrpc_connection_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rxnet->conn_lock)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	read_lock(&rxnet->conn_lock);
+	return seq_list_start_head(&rxnet->conn_proc_list, *_pos);
+}
+
+static void *rxrpc_connection_seq_next(struct seq_file *seq, void *v,
+				       loff_t *pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	return seq_list_next(v, &rxnet->conn_proc_list, pos);
+}
+
+static void rxrpc_connection_seq_stop(struct seq_file *seq, void *v)
+	__releases(rxnet->conn_lock)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	read_unlock(&rxnet->conn_lock);
+}
+
+static int rxrpc_connection_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_connection *conn;
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	const char *state;
+	char lbuff[RXRPC_PROC_ADDRBUF_SIZE], rbuff[RXRPC_PROC_ADDRBUF_SIZE];
+
+	if (v == &rxnet->conn_proc_list) {
+		seq_puts(seq,
+			 "Proto Local                                          "
+			 " Remote                                         "
+			 " SvID ConnID   End Ref Act State    Key     "
+			 " Serial   ISerial  CallId0  CallId1  CallId2  CallId3\n"
+			 );
+		return 0;
+	}
+
+	conn = list_entry(v, struct rxrpc_connection, proc_link);
+	if (conn->state == RXRPC_CONN_SERVICE_PREALLOC) {
+		strcpy(lbuff, "no_local");
+		strcpy(rbuff, "no_connection");
+		goto print;
+	}
+
+	scnprintf(lbuff, sizeof(lbuff), "%pISpc", &conn->local->srx.transport);
+	scnprintf(rbuff, sizeof(rbuff), "%pISpc", &conn->peer->srx.transport);
+print:
+	state = rxrpc_is_conn_aborted(conn) ?
+		rxrpc_call_completions[conn->completion] :
+		rxrpc_conn_states[conn->state];
+	seq_printf(seq,
+		   "UDP   %-47.47s %-47.47s %4x %08x %s %3u %3d"
+		   " %s %08x %08x %08x %08x %08x %08x %08x\n",
+		   lbuff,
+		   rbuff,
+		   conn->service_id,
+		   conn->proto.cid,
+		   rxrpc_conn_is_service(conn) ? "Svc" : "Clt",
+		   refcount_read(&conn->ref),
+		   atomic_read(&conn->active),
+		   state,
+		   key_serial(conn->key),
+		   conn->tx_serial,
+		   conn->hi_serial,
+		   conn->channels[0].call_id,
+		   conn->channels[1].call_id,
+		   conn->channels[2].call_id,
+		   conn->channels[3].call_id);
+
+	return 0;
+}
+
+const struct seq_operations rxrpc_connection_seq_ops = {
+	.start  = rxrpc_connection_seq_start,
+	.next   = rxrpc_connection_seq_next,
+	.stop   = rxrpc_connection_seq_stop,
+	.show   = rxrpc_connection_seq_show,
+};
+
+/*
+ * generate a list of extant virtual bundles in /proc/net/rxrpc/bundles
+ */
+static void *rxrpc_bundle_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rxnet->conn_lock)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	read_lock(&rxnet->conn_lock);
+	return seq_list_start_head(&rxnet->bundle_proc_list, *_pos);
+}
+
+static void *rxrpc_bundle_seq_next(struct seq_file *seq, void *v,
+				       loff_t *pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	return seq_list_next(v, &rxnet->bundle_proc_list, pos);
+}
+
+static void rxrpc_bundle_seq_stop(struct seq_file *seq, void *v)
+	__releases(rxnet->conn_lock)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	read_unlock(&rxnet->conn_lock);
+}
+
+static int rxrpc_bundle_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_bundle *bundle;
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	char lbuff[RXRPC_PROC_ADDRBUF_SIZE], rbuff[RXRPC_PROC_ADDRBUF_SIZE];
+
+	if (v == &rxnet->bundle_proc_list) {
+		seq_puts(seq,
+			 "Proto Local                                          "
+			 " Remote                                         "
+			 " SvID Ref Act Flg Key      |"
+			 " Bundle   Conn_0   Conn_1   Conn_2   Conn_3\n"
+			 );
+		return 0;
+	}
+
+	bundle = list_entry(v, struct rxrpc_bundle, proc_link);
+
+	scnprintf(lbuff, sizeof(lbuff), "%pISpc", &bundle->local->srx.transport);
+	scnprintf(rbuff, sizeof(rbuff), "%pISpc", &bundle->peer->srx.transport);
+	seq_printf(seq,
+		   "UDP   %-47.47s %-47.47s %4x %3u %3d"
+		   " %c%c%c %08x | %08x %08x %08x %08x %08x\n",
+		   lbuff,
+		   rbuff,
+		   bundle->service_id,
+		   refcount_read(&bundle->ref),
+		   atomic_read(&bundle->active),
+		   bundle->try_upgrade ? 'U' : '-',
+		   bundle->exclusive ? 'e' : '-',
+		   bundle->upgrade ? 'u' : '-',
+		   key_serial(bundle->key),
+		   bundle->debug_id,
+		   bundle->conn_ids[0],
+		   bundle->conn_ids[1],
+		   bundle->conn_ids[2],
+		   bundle->conn_ids[3]);
+
+	return 0;
+}
+
+const struct seq_operations rxrpc_bundle_seq_ops = {
+	.start  = rxrpc_bundle_seq_start,
+	.next   = rxrpc_bundle_seq_next,
+	.stop   = rxrpc_bundle_seq_stop,
+	.show   = rxrpc_bundle_seq_show,
+};
+
+/*
+ * generate a list of extant virtual peers in /proc/net/rxrpc/peers
+ */
+static int rxrpc_peer_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_peer *peer;
+	time64_t now;
+	char lbuff[RXRPC_PROC_ADDRBUF_SIZE], rbuff[RXRPC_PROC_ADDRBUF_SIZE];
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq,
+			 "Proto Local                                           Remote                                          Use SST   Maxd LastUse      RTT      RTO\n"
+			 );
+		return 0;
+	}
+
+	peer = list_entry(v, struct rxrpc_peer, hash_link);
+
+	scnprintf(lbuff, sizeof(lbuff), "%pISpc", &peer->local->srx.transport);
+
+	scnprintf(rbuff, sizeof(rbuff), "%pISpc", &peer->srx.transport);
+
+	now = ktime_get_seconds();
+	seq_printf(seq,
+		   "UDP   %-47.47s %-47.47s %3u %4u %5u %6ds %8d %8d\n",
+		   lbuff,
+		   rbuff,
+		   refcount_read(&peer->ref),
+		   peer->cong_ssthresh,
+		   peer->max_data,
+		   (s32)now - (s32)READ_ONCE(peer->last_tx_at),
+		   READ_ONCE(peer->recent_srtt_us),
+		   READ_ONCE(peer->recent_rto_us));
+
+	return 0;
+}
+
+static void *rxrpc_peer_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rcu)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	unsigned int bucket, n;
+	unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
+	void *p;
+
+	rcu_read_lock();
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	n = *_pos & ((1U << shift) - 1);
+	bucket = *_pos >> shift;
+	for (;;) {
+		if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
+			*_pos = UINT_MAX;
+			return NULL;
+		}
+		if (n == 0) {
+			if (bucket == 0)
+				return SEQ_START_TOKEN;
+			*_pos += 1;
+			n++;
+		}
+
+		p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
+		if (p)
+			return p;
+		bucket++;
+		n = 1;
+		*_pos = (bucket << shift) | n;
+	}
+}
+
+static void *rxrpc_peer_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	unsigned int bucket, n;
+	unsigned int shift = 32 - HASH_BITS(rxnet->peer_hash);
+	void *p;
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	bucket = *_pos >> shift;
+
+	p = seq_hlist_next_rcu(v, &rxnet->peer_hash[bucket], _pos);
+	if (p)
+		return p;
+
+	for (;;) {
+		bucket++;
+		n = 1;
+		*_pos = (bucket << shift) | n;
+
+		if (bucket >= HASH_SIZE(rxnet->peer_hash)) {
+			*_pos = UINT_MAX;
+			return NULL;
+		}
+		if (n == 0) {
+			*_pos += 1;
+			n++;
+		}
+
+		p = seq_hlist_start_rcu(&rxnet->peer_hash[bucket], n - 1);
+		if (p)
+			return p;
+	}
+}
+
+static void rxrpc_peer_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+
+const struct seq_operations rxrpc_peer_seq_ops = {
+	.start  = rxrpc_peer_seq_start,
+	.next   = rxrpc_peer_seq_next,
+	.stop   = rxrpc_peer_seq_stop,
+	.show   = rxrpc_peer_seq_show,
+};
+
+/*
+ * Generate a list of extant virtual local endpoints in /proc/net/rxrpc/locals
+ */
+static int rxrpc_local_seq_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_local *local;
+	char lbuff[RXRPC_PROC_ADDRBUF_SIZE];
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq,
+			 "Proto Local                                          "
+			 " Use Act RxQ\n");
+		return 0;
+	}
+
+	local = hlist_entry(v, struct rxrpc_local, link);
+
+	scnprintf(lbuff, sizeof(lbuff), "%pISpc", &local->srx.transport);
+
+	seq_printf(seq,
+		   "UDP   %-47.47s %3u %3u %3u\n",
+		   lbuff,
+		   refcount_read(&local->ref),
+		   atomic_read(&local->active_users),
+		   local->rx_queue.qlen);
+
+	return 0;
+}
+
+static void *rxrpc_local_seq_start(struct seq_file *seq, loff_t *_pos)
+	__acquires(rcu)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+	unsigned int n;
+
+	rcu_read_lock();
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	n = *_pos;
+	if (n == 0)
+		return SEQ_START_TOKEN;
+
+	return seq_hlist_start_rcu(&rxnet->local_endpoints, n - 1);
+}
+
+static void *rxrpc_local_seq_next(struct seq_file *seq, void *v, loff_t *_pos)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_net(seq));
+
+	if (*_pos >= UINT_MAX)
+		return NULL;
+
+	return seq_hlist_next_rcu(v, &rxnet->local_endpoints, _pos);
+}
+
+static void rxrpc_local_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+const struct seq_operations rxrpc_local_seq_ops = {
+	.start  = rxrpc_local_seq_start,
+	.next   = rxrpc_local_seq_next,
+	.stop   = rxrpc_local_seq_stop,
+	.show   = rxrpc_local_seq_show,
+};
+
+/*
+ * Display stats in /proc/net/rxrpc/stats
+ */
+int rxrpc_stats_show(struct seq_file *seq, void *v)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_single_net(seq));
+
+	seq_printf(seq,
+		   "Data     : send=%u sendf=%u fail=%u emsz=%u\n",
+		   atomic_read(&rxnet->stat_tx_data_send),
+		   atomic_read(&rxnet->stat_tx_data_send_frag),
+		   atomic_read(&rxnet->stat_tx_data_send_fail),
+		   atomic_read(&rxnet->stat_tx_data_send_msgsize));
+	seq_printf(seq,
+		   "Data-Tx  : nr=%u retrans=%u uf=%u cwr=%u\n",
+		   atomic_read(&rxnet->stat_tx_data),
+		   atomic_read(&rxnet->stat_tx_data_retrans),
+		   atomic_read(&rxnet->stat_tx_data_underflow),
+		   atomic_read(&rxnet->stat_tx_data_cwnd_reset));
+	seq_printf(seq,
+		   "Data-Rx  : nr=%u reqack=%u jumbo=%u\n",
+		   atomic_read(&rxnet->stat_rx_data),
+		   atomic_read(&rxnet->stat_rx_data_reqack),
+		   atomic_read(&rxnet->stat_rx_data_jumbo));
+	seq_printf(seq,
+		   "Ack      : fill=%u send=%u skip=%u\n",
+		   atomic_read(&rxnet->stat_tx_ack_fill),
+		   atomic_read(&rxnet->stat_tx_ack_send),
+		   atomic_read(&rxnet->stat_tx_ack_skip));
+	seq_printf(seq,
+		   "Ack-Tx   : req=%u dup=%u oos=%u exw=%u nos=%u png=%u prs=%u dly=%u idl=%u\n",
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_REQUESTED]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_DUPLICATE]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_OUT_OF_SEQUENCE]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_EXCEEDS_WINDOW]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_NOSPACE]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_PING]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_PING_RESPONSE]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_DELAY]),
+		   atomic_read(&rxnet->stat_tx_acks[RXRPC_ACK_IDLE]));
+	seq_printf(seq,
+		   "Ack-Rx   : req=%u dup=%u oos=%u exw=%u nos=%u png=%u prs=%u dly=%u idl=%u z=%u\n",
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_REQUESTED]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_DUPLICATE]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_OUT_OF_SEQUENCE]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_EXCEEDS_WINDOW]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_NOSPACE]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_PING]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_PING_RESPONSE]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_DELAY]),
+		   atomic_read(&rxnet->stat_rx_acks[RXRPC_ACK_IDLE]),
+		   atomic_read(&rxnet->stat_rx_acks[0]));
+	seq_printf(seq,
+		   "Why-Req-A: acklost=%u mrtt=%u ortt=%u stall=%u jwin=%u\n",
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_ack_lost]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_more_rtt]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_old_rtt]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_app_stall]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_jumbo_win]));
+	seq_printf(seq,
+		   "Why-Req-A: nolast=%u retx=%u slows=%u smtxw=%u\n",
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_no_srv_last]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_retrans]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_slow_start]),
+		   atomic_read(&rxnet->stat_why_req_ack[rxrpc_reqack_small_txwin]));
+	seq_printf(seq,
+		   "Jumbo-Tx : %u,%u,%u,%u,%u,%u,%u,%u,%u,%u\n",
+		   atomic_read(&rxnet->stat_tx_jumbo[0]),
+		   atomic_read(&rxnet->stat_tx_jumbo[1]),
+		   atomic_read(&rxnet->stat_tx_jumbo[2]),
+		   atomic_read(&rxnet->stat_tx_jumbo[3]),
+		   atomic_read(&rxnet->stat_tx_jumbo[4]),
+		   atomic_read(&rxnet->stat_tx_jumbo[5]),
+		   atomic_read(&rxnet->stat_tx_jumbo[6]),
+		   atomic_read(&rxnet->stat_tx_jumbo[7]),
+		   atomic_read(&rxnet->stat_tx_jumbo[8]),
+		   atomic_read(&rxnet->stat_tx_jumbo[9]));
+	seq_printf(seq,
+		   "Jumbo-Rx : %u,%u,%u,%u,%u,%u,%u,%u,%u,%u\n",
+		   atomic_read(&rxnet->stat_rx_jumbo[0]),
+		   atomic_read(&rxnet->stat_rx_jumbo[1]),
+		   atomic_read(&rxnet->stat_rx_jumbo[2]),
+		   atomic_read(&rxnet->stat_rx_jumbo[3]),
+		   atomic_read(&rxnet->stat_rx_jumbo[4]),
+		   atomic_read(&rxnet->stat_rx_jumbo[5]),
+		   atomic_read(&rxnet->stat_rx_jumbo[6]),
+		   atomic_read(&rxnet->stat_rx_jumbo[7]),
+		   atomic_read(&rxnet->stat_rx_jumbo[8]),
+		   atomic_read(&rxnet->stat_rx_jumbo[9]));
+	seq_printf(seq,
+		   "Buffers  : txb=%u rxb=%u\n",
+		   atomic_read(&rxrpc_nr_txbuf),
+		   atomic_read(&rxrpc_n_rx_skbs));
+	seq_printf(seq,
+		   "IO-thread: loops=%u\n",
+		   atomic_read(&rxnet->stat_io_loop));
+	return 0;
+}
+
+/*
+ * Clear stats if /proc/net/rxrpc/stats is written to.
+ */
+int rxrpc_stats_clear(struct file *file, char *buf, size_t size)
+{
+	struct seq_file *m = file->private_data;
+	struct rxrpc_net *rxnet = rxrpc_net(seq_file_single_net(m));
+
+	if (size > 1 || (size == 1 && buf[0] != '\n'))
+		return -EINVAL;
+
+	atomic_set(&rxnet->stat_tx_data, 0);
+	atomic_set(&rxnet->stat_tx_data_retrans, 0);
+	atomic_set(&rxnet->stat_tx_data_underflow, 0);
+	atomic_set(&rxnet->stat_tx_data_cwnd_reset, 0);
+	atomic_set(&rxnet->stat_tx_data_send, 0);
+	atomic_set(&rxnet->stat_tx_data_send_frag, 0);
+	atomic_set(&rxnet->stat_tx_data_send_fail, 0);
+	atomic_set(&rxnet->stat_rx_data, 0);
+	atomic_set(&rxnet->stat_rx_data_reqack, 0);
+	atomic_set(&rxnet->stat_rx_data_jumbo, 0);
+
+	atomic_set(&rxnet->stat_tx_ack_fill, 0);
+	atomic_set(&rxnet->stat_tx_ack_send, 0);
+	atomic_set(&rxnet->stat_tx_ack_skip, 0);
+	memset(&rxnet->stat_tx_acks, 0, sizeof(rxnet->stat_tx_acks));
+	memset(&rxnet->stat_rx_acks, 0, sizeof(rxnet->stat_rx_acks));
+	memset(&rxnet->stat_tx_jumbo, 0, sizeof(rxnet->stat_tx_jumbo));
+	memset(&rxnet->stat_rx_jumbo, 0, sizeof(rxnet->stat_rx_jumbo));
+
+	memset(&rxnet->stat_why_req_ack, 0, sizeof(rxnet->stat_why_req_ack));
+
+	atomic_set(&rxnet->stat_io_loop, 0);
+	return size;
+}