linux-kernel - [PATCH 5/7] uprobes: move the initialization of utask->xol_vaddr from pre_ssout() to xol_get_insn

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Message-ID: <20240929144248.GA9483@redhat.com>
Date: Sun, 29 Sep 2024 16:42:48 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrii Nakryiko <andrii@...nel.org>, Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc: Liao Chang <liaochang1@...wei.com>, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH 5/7] uprobes: move the initialization of utask->xol_vaddr
 from pre_ssout() to xol_get_insn_slot()

This simplifies the code and makes xol_get_insn_slot() symmetric with
xol_free_insn_slot() which clears utask->xol_vaddr.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c | 22 ++++++++--------------
 1 file changed, 8 insertions(+), 14 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index bfe106ecad38..a7223be5ac2e 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1649,21 +1649,19 @@ static unsigned long xol_take_insn_slot(struct xol_area *area)
 
 /*
  * xol_get_insn_slot - allocate a slot for xol.
- * Returns the allocated slot address or 0.
  */
-static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
+static bool xol_get_insn_slot(struct uprobe *uprobe)
 {
-	struct xol_area *area;
-	unsigned long xol_vaddr;
+	struct uprobe_task *utask = current->utask;
+	struct xol_area *area = get_xol_area();
 
-	area = get_xol_area();
 	if (!area)
-		return 0;
+		return false;
 
-	xol_vaddr = xol_take_insn_slot(area);
-	arch_uprobe_copy_ixol(area->page, xol_vaddr,
+	utask->xol_vaddr = xol_take_insn_slot(area);
+	arch_uprobe_copy_ixol(area->page, utask->xol_vaddr,
 			      &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
-	return xol_vaddr;
+	return true;
 }
 
 /*
@@ -1951,21 +1949,17 @@ static int
 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
 {
 	struct uprobe_task *utask = current->utask;
-	unsigned long xol_vaddr;
 	int err;
 
 	if (!try_get_uprobe(uprobe))
 		return -EINVAL;
 
-	xol_vaddr = xol_get_insn_slot(uprobe);
-	if (!xol_vaddr) {
+	if (!xol_get_insn_slot(uprobe)) {
 		err = -ENOMEM;
 		goto err_out;
 	}
 
-	utask->xol_vaddr = xol_vaddr;
 	utask->vaddr = bp_vaddr;
-
 	err = arch_uprobe_pre_xol(&uprobe->arch, regs);
 	if (unlikely(err)) {
 		xol_free_insn_slot(current);
-- 
2.25.1.362.g51ebf55