linux-kernel - [RFC PATCH 3/6] riscv: insn: __read_insn use copy_from_X

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Message-ID: <20250722173829.984082-4-jesse@rivosinc.com>
Date: Tue, 22 Jul 2025 10:38:26 -0700
From: Jesse Taube <jesse@...osinc.com>
To: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Oleg Nesterov <oleg@...hat.com>,
	Jesse Taube <jesse@...osinc.com>,
	Himanshu Chauhan <hchauhan@...tanamicro.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Deepak Gupta <debug@...osinc.com>,
	Andrew Jones <ajones@...tanamicro.com>,
	Atish Patra <atishp@...osinc.com>,
	Anup Patel <apatel@...tanamicro.com>,
	Mayuresh Chitale <mchitale@...tanamicro.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	WangYuli <wangyuli@...ontech.com>,
	Huacai Chen <chenhuacai@...nel.org>,
	Nam Cao <namcao@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Mike Rapoport (Microsoft)" <rppt@...nel.org>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Joel Granados <joel.granados@...nel.org>,
	Clément Léger <cleger@...osinc.com>,
	Celeste Liu <coelacanthushex@...il.com>,
	Evan Green <evan@...osinc.com>,
	Nylon Chen <nylon.chen@...ive.com>
Subject: [RFC PATCH 3/6] riscv: insn: __read_insn use copy_from_X_nofault

__read_insn was using get_user for user space reads and direct
dereferencing for kernel space reads.
Update to use copy_from_user_nofault, copy_from_kernel_nofault for this
as get_user is user context only and may sleep.

Signed-off-by: Jesse Taube <jesse@...osinc.com>
---
Squash with previous commit as it's breaks bisectability.
Separated as i'm unsure if copy_from_user_nofault is an acceptable
replacement.
---
 arch/riscv/kernel/insn.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/insn.c b/arch/riscv/kernel/insn.c
index dd2a6ef9fd25..b8e5202ddced 100644
--- a/arch/riscv/kernel/insn.c
+++ b/arch/riscv/kernel/insn.c
@@ -2,6 +2,9 @@
 /*
  * Copyright 2025 Rivos, Inc
  */
+
+#include <linux/uaccess.h>
+
 #include <asm/insn.h>
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>
@@ -11,10 +14,9 @@
 	int __ret;					\
 							\
 	if (user_mode(regs)) {				\
-		__ret = get_user(insn, (type __user *) insn_addr); \
+		__ret = copy_from_user_nofault(&insn, (const type __user *) insn_addr, sizeof(type)); \
 	} else {					\
-		insn = *(type *)insn_addr;		\
-		__ret = 0;				\
+		__ret = copy_from_kernel_nofault(&insn, (const type *) insn_addr, sizeof(type)); \
 	}						\
 							\
 	__ret;						\
-- 
2.43.0