linux-kernel - [tip: perf/core] uprobes: don't abuse get_utask() in pre_ssout() and prepare

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Message-ID: <172838551619.1442.10049185498465124240.tip-bot2@tip-bot2>
Date: Tue, 08 Oct 2024 11:05:16 -0000
From: "tip-bot2 for Oleg Nesterov" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: perf/core] uprobes: don't abuse get_utask() in pre_ssout() and
 prepare_uretprobe()

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     b302d5a6fff5dd7ddb1e4752d60c0eaa4cc4f7f3
Gitweb:        https://git.kernel.org/tip/b302d5a6fff5dd7ddb1e4752d60c0eaa4cc4f7f3
Author:        Oleg Nesterov <oleg@...hat.com>
AuthorDate:    Sun, 29 Sep 2024 16:42:30 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Mon, 07 Oct 2024 09:28:44 +02:00

uprobes: don't abuse get_utask() in pre_ssout() and prepare_uretprobe()

handle_swbp() calls get_utask() before prepare_uretprobe() or pre_ssout()
can be called, they can simply use current->utask which can't be NULL.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20240929144230.GA9468@redhat.com
---
 kernel/events/uprobes.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 5106dc1..15e91a3 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1905,18 +1905,14 @@ static void cleanup_return_instances(struct uprobe_task *utask, bool chained,
 
 static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
 {
-	struct return_instance *ri;
-	struct uprobe_task *utask;
+	struct uprobe_task *utask = current->utask;
 	unsigned long orig_ret_vaddr, trampoline_vaddr;
+	struct return_instance *ri;
 	bool chained;
 
 	if (!get_xol_area())
 		return;
 
-	utask = get_utask();
-	if (!utask)
-		return;
-
 	if (utask->depth >= MAX_URETPROBE_DEPTH) {
 		printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
 				" nestedness limit pid/tgid=%d/%d\n",
@@ -1977,14 +1973,10 @@ fail:
 static int
 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
 {
-	struct uprobe_task *utask;
+	struct uprobe_task *utask = current->utask;
 	unsigned long xol_vaddr;
 	int err;
 
-	utask = get_utask();
-	if (!utask)
-		return -ENOMEM;
-
 	if (!try_get_uprobe(uprobe))
 		return -EINVAL;