linux-kernel - [PATCH] riscv: Grab text_mutex before patching jump-labels

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Message-Id: <20200723163628.82794-1-kernel@esmil.dk>
Date:   Thu, 23 Jul 2020 18:36:28 +0200
From:   Emil Renner Berthing <kernel@...il.dk>
To:     linux-riscv@...ts.infradead.org,
        Palmer Dabbelt <palmer@...belt.com>
Cc:     Emil Renner Berthing <kernel@...il.dk>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Björn Töpel <bjorn.topel@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] riscv: Grab text_mutex before patching jump-labels

Like other arch's we use patch_text_nosync or equivalent
to patch the jump-labels, but also like other arch's we
need to hold the text_mutex before calling that.

Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
---

Fixes: b6e0878a4ec8 ("riscv: Add jump-label implementation")
..that is already in riscv/for-next.

Palmer: Sorry, I didn't notice this before. Feel free to
squash this into the commit above if you like.
---
 arch/riscv/kernel/jump_label.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
index 1bab1abc1aa5..20e09056d141 100644
--- a/arch/riscv/kernel/jump_label.c
+++ b/arch/riscv/kernel/jump_label.c
@@ -4,8 +4,10 @@
  *
  * Based on arch/arm64/kernel/jump_label.c
  */
-#include <linux/kernel.h>
 #include <linux/jump_label.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/mutex.h>
 #include <asm/bug.h>
 #include <asm/patch.h>
 
@@ -33,7 +35,9 @@ void arch_jump_label_transform(struct jump_entry *entry,
 		insn = RISCV_INSN_NOP;
 	}
 
+	mutex_lock(&text_mutex);
 	patch_text_nosync(addr, &insn, sizeof(insn));
+	mutex_unlock(&text_mutex);
 }
 
 void arch_jump_label_transform_static(struct jump_entry *entry,
-- 
2.27.0