linux-kernel - [PATCH 3/3] Revert "kernel/debug: Mask KGDB NMI upon entry"

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Message-ID: <20250129082535.3.I2254953cd852f31f354456689d68b2d910de3fbe@changeid>
Date: Wed, 29 Jan 2025 08:25:52 -0800
From: Douglas Anderson <dianders@...omium.org>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Daniel Thompson <danielt@...nel.org>
Cc: "Dr . David Alan Gilbert" <linux@...blig.org>,
	kgdb-bugreport@...ts.sourceforge.net,
	Anton Vorontsov <anton.vorontsov@...aro.org>,
	Sumit Garg <sumit.garg@...aro.org>,
	linux-serial@...r.kernel.org,
	Douglas Anderson <dianders@...omium.org>,
	Jason Wessel <jason.wessel@...driver.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] Revert "kernel/debug: Mask KGDB NMI upon entry"

This reverts commit 5a14fead07bcf4e0acc877a8d9e1d1f40a441153.

No architectures ever implemented `enable_nmi` since the later patches
in the series adding it never landed. It's been a long time. Drop it.

NOTE: this is not a clean revert due to changes in the file in the
meantime.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 include/linux/kgdb.h      |  3 ---
 kernel/debug/debug_core.c | 14 +++-----------
 2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index 14739952698b..5eebbe7a3545 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -257,7 +257,6 @@ extern void kgdb_arch_late(void);
  * hardware breakpoints.
  * @correct_hw_break: Allow an architecture to specify how to correct the
  * hardware debug registers.
- * @enable_nmi: Manage NMI-triggered entry to KGDB
  */
 struct kgdb_arch {
 	unsigned char		gdb_bpt_instr[BREAK_INSTR_SIZE];
@@ -270,8 +269,6 @@ struct kgdb_arch {
 	void	(*disable_hw_break)(struct pt_regs *regs);
 	void	(*remove_all_hw_break)(void);
 	void	(*correct_hw_break)(void);
-
-	void	(*enable_nmi)(bool on);
 };
 
 /**
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index ce1bb2301c06..0b9495187fba 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -837,10 +837,6 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 {
 	struct kgdb_state kgdb_var;
 	struct kgdb_state *ks = &kgdb_var;
-	int ret = 0;
-
-	if (arch_kgdb_ops.enable_nmi)
-		arch_kgdb_ops.enable_nmi(0);
 	/*
 	 * Avoid entering the debugger if we were triggered due to an oops
 	 * but panic_timeout indicates the system should automatically
@@ -858,15 +854,11 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
 	ks->linux_regs		= regs;
 
 	if (kgdb_reenter_check(ks))
-		goto out; /* Ouch, double exception ! */
+		return 0; /* Ouch, double exception ! */
 	if (kgdb_info[ks->cpu].enter_kgdb != 0)
-		goto out;
+		return 0;
 
-	ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
-out:
-	if (arch_kgdb_ops.enable_nmi)
-		arch_kgdb_ops.enable_nmi(1);
-	return ret;
+	return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
 }
 NOKPROBE_SYMBOL(kgdb_handle_exception);
 
-- 
2.48.1.262.g85cc9f2d1e-goog