linux-kernel - [PATCH v3 8/8] arm64: kprobe: Keep NMI maskabled while kprobe is stepping xol

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Date: Mon, 15 Apr 2024 06:47:58 +0000
From: Liao Chang <liaochang1@...wei.com>
To: <catalin.marinas@....com>, <will@...nel.org>, <maz@...nel.org>,
	<oliver.upton@...ux.dev>, <james.morse@....com>, <suzuki.poulose@....com>,
	<yuzenghui@...wei.com>, <tglx@...utronix.de>, <mark.rutland@....com>,
	<ardb@...nel.org>, <broonie@...nel.org>, <liaochang1@...wei.com>,
	<anshuman.khandual@....com>, <miguel.luis@...cle.com>, <joey.gouly@....com>,
	<ryan.roberts@....com>, <jeremy.linton@....com>, <ericchancf@...gle.com>,
	<kristina.martsenko@....com>, <robh@...nel.org>,
	<scott@...amperecomputing.com>, <songshuaishuai@...ylab.org>,
	<shijie@...amperecomputing.com>, <akpm@...ux-foundation.org>,
	<bhe@...hat.com>, <horms@...nel.org>, <mhiramat@...nel.org>,
	<rmk+kernel@...linux.org.uk>, <shahuang@...hat.com>,
	<takakura@...inux.co.jp>, <dianders@...omium.org>, <swboyd@...omium.org>,
	<sumit.garg@...aro.org>, <frederic@...nel.org>, <reijiw@...gle.com>,
	<akihiko.odaki@...nix.com>, <ruanjinjie@...wei.com>
CC: <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<kvmarm@...ts.linux.dev>
Subject: [PATCH v3 8/8] arm64: kprobe: Keep NMI maskabled while kprobe is stepping xol

Keeping NMI maskable while executing instruction out of line, otherwise,
add kprobe on the functions invoken while handling NMI will cause kprobe
reenter bug and kernel panic.

Signed-off-by: Liao Chang <liaochang1@...wei.com>
---
 arch/arm64/include/asm/daifflags.h | 2 ++
 arch/arm64/kernel/probes/kprobes.c | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/daifflags.h b/arch/arm64/include/asm/daifflags.h
index 1196eb85aa8d..60fd3b25fd73 100644
--- a/arch/arm64/include/asm/daifflags.h
+++ b/arch/arm64/include/asm/daifflags.h
@@ -17,6 +17,8 @@
 #define DAIF_PROCCTX_NOIRQ	(PSR_I_BIT | PSR_F_BIT)
 #define DAIF_ERRCTX		(PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
 #define DAIF_MASK		(PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
+#define DAIF_ALLINT_MASK	\
+	(system_uses_nmi() ? (ALLINT_ALLINT | DAIF_MASK) : (DAIF_MASK))
 
 /*
  * For Arm64 processor support Armv8.8 or later, kernel supports three types
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index 327855a11df2..e8c2b993bbb8 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -187,13 +187,13 @@ static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb,
 						struct pt_regs *regs)
 {
 	kcb->saved_irqflag = regs->pstate & DAIF_MASK;
-	regs->pstate |= DAIF_MASK;
+	regs->pstate |= DAIF_ALLINT_MASK;
 }
 
 static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb,
 						struct pt_regs *regs)
 {
-	regs->pstate &= ~DAIF_MASK;
+	regs->pstate &= ~DAIF_ALLINT_MASK;
 	regs->pstate |= kcb->saved_irqflag;
 }
 
-- 
2.34.1