linux-kernel - [PATCH -next V17 3/7] riscv: entry: Add noinstr to prevent instrumentation inserted

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Message-Id: <20230222033021.983168-4-guoren@kernel.org>
Date:   Tue, 21 Feb 2023 22:30:17 -0500
From:   guoren@...nel.org
To:     arnd@...db.de, guoren@...nel.org, palmer@...osinc.com,
        tglx@...utronix.de, peterz@...radead.org, luto@...nel.org,
        conor.dooley@...rochip.com, heiko@...ech.de, jszhang@...nel.org,
        lazyparser@...il.com, falcon@...ylab.org, chenhuacai@...nel.org,
        apatel@...tanamicro.com, atishp@...shpatra.org,
        mark.rutland@....com, ben@...adent.org.uk, bjorn@...nel.org,
        palmer@...belt.com
Cc:     linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Guo Ren <guoren@...ux.alibaba.com>,
        Björn Töpel <bjorn@...osinc.com>
Subject: [PATCH -next V17 3/7] riscv: entry: Add noinstr to prevent instrumentation inserted

From: Guo Ren <guoren@...ux.alibaba.com>

Without noinstr the compiler is free to insert instrumentation (think
all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
yet ready to run this early in the entry path, for instance it could
rely on RCU which isn't on yet, or expect lockdep state. (by peterz)

Link: https://lore.kernel.org/linux-riscv/YxcQ6NoPf3AH0EXe@hirez.programming.kicks-ass.net/
Reviewed-by: Björn Töpel <bjorn@...osinc.com>
Suggested-by: Peter Zijlstra <peterz@...radead.org>
Tested-by: Jisheng Zhang <jszhang@...nel.org>
Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...nel.org>
---
 arch/riscv/kernel/traps.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index f6fda94e8e59..02727a4fe8be 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -119,9 +119,9 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,
 }
 
 #if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE)
-#define __trap_section		__section(".xip.traps")
+#define __trap_section __noinstr_section(".xip.traps")
 #else
-#define __trap_section
+#define __trap_section noinstr
 #endif
 #define DO_ERROR_INFO(name, signo, code, str)				\
 asmlinkage __visible __trap_section void name(struct pt_regs *regs)	\
-- 
2.36.1