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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, james.morse@arm.com,
	mark.rutland@arm.com, maz@kernel.org, will@kernel.org,
	joey.gouly@arm.com
Subject: [PATCH v2 12/19] arm64: entry: improve bad_mode()
Date: Wed, 19 May 2021 13:38:55 +0100	[thread overview]
Message-ID: <20210519123902.2452-13-mark.rutland@arm.com> (raw)
In-Reply-To: <20210519123902.2452-1-mark.rutland@arm.com>

Our use of bad_mode() has a few rough edges:

* AArch64 doesn't use the term "mode", and refers to "Execution
  states", "Exception levels", and "Selected stack pointer".

* We log the exception type (SYNC/IRQ/FIQ/SError), but not the actual
  "mode" (though this can be deocded from the SPSR value).

* We use bad_mode() as a second-level handler for unexpected synchronous
  exceptions, where the "mode" is legitimate, but the specific exception
  is not.

* We dump the ESR value, but call this "code", and so it's not clear to
  all readers that this is the ESR.

... and all of this can be someqhat opaque to those who aren't extremely
familiar with the code.

Let's make this a bit clearer by having bad_mode() log "Unhandled
${TYPE} exception" rather than "Bad mode in ${TYPE} handler", using
"ESR" rather than "code", and having the final panic() log "Unhandled
exception" rather than "Bad mode".

In future we'd like to log the specific architectural vector rather than
just the type of exception, so we also split the core of basd_mode() out
into a helper called __panic_unhandled(), which takes the vector as a
string argument.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/entry-common.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 25531a0b547e..b43ef1a918a4 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -160,31 +160,32 @@ static void do_interrupt_handler(struct pt_regs *regs,
 extern void (*handle_arch_irq)(struct pt_regs *);
 extern void (*handle_arch_fiq)(struct pt_regs *);
 
-/*
- * bad_mode handles the impossible case in the exception vector. This is always
- * fatal.
- */
-asmlinkage void noinstr bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
+static void noinstr __panic_unhandled(struct pt_regs *regs, const char *vector,
+				      unsigned int esr)
 {
-	const char *handler[] = {
-		"Synchronous Abort",
-		"IRQ",
-		"FIQ",
-		"Error"
-	};
-
 	arm64_enter_nmi(regs);
 
 	console_verbose();
 
-	pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
-		handler[reason], smp_processor_id(), esr,
+	pr_crit("Unhandled %s exception on CPU%d, ESR 0x%08x -- %s\n",
+		vector, smp_processor_id(), esr,
 		esr_get_class_string(esr));
 
 	__show_regs(regs);
-	panic("bad mode");
+	panic("Unhandled exception");
 }
 
+asmlinkage void noinstr bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
+{
+	const char *handler[] = {
+		"Synchronous Abort",
+		"IRQ",
+		"FIQ",
+		"Error"
+	};
+
+	__panic_unhandled(regs, handler[reason], esr);
+}
 
 #ifdef CONFIG_ARM64_ERRATUM_1463225
 static DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);
-- 
2.11.0


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  parent reply	other threads:[~2021-05-19 13:10 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-19 12:38 [PATCH v2 00/19] arm64: entry: migrate more code to C Mark Rutland
2021-05-19 12:38 ` [PATCH v2 01/19] arm64: remove redundant local_daif_mask() in bad_mode() Mark Rutland
2021-05-21 10:39   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 02/19] arm64: entry: unmask IRQ+FIQ after EL0 handling Mark Rutland
2021-05-25 16:45   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 03/19] arm64: entry: convert SError handlers to C Mark Rutland
2021-05-25 13:38   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 04/19] arm64: entry: move arm64_preempt_schedule_irq to entry-common.c Mark Rutland
2021-05-21 11:00   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 05/19] arm64: entry: move preempt logic to C Mark Rutland
2021-05-25 12:50   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 06/19] arm64: entry: add a call_on_irq_stack helper Mark Rutland
2021-05-19 14:46   ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 07/19] arm64: entry: convert IRQ+FIQ handlers to C Mark Rutland
2021-05-21 13:19   ` Joey Gouly
2021-05-21 15:23     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 08/19] arm64: entry: organise entry handlers consistently Mark Rutland
2021-05-21 16:04   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 09/19] arm64: entry: organise entry vectors consistently Mark Rutland
2021-05-21 16:07   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 10/19] arm64: entry: consolidate EL1 exception returns Mark Rutland
2021-05-21 16:22   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 11/19] arm64: entry: move bad_mode() to entry-common.c Mark Rutland
2021-05-21 16:46   ` Joey Gouly
2021-05-19 12:38 ` Mark Rutland [this message]
2021-05-21 17:02   ` [PATCH v2 12/19] arm64: entry: improve bad_mode() Joey Gouly
2021-05-21 17:10     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 13/19] arm64: entry: template the entry asm functions Mark Rutland
2021-05-21 17:16   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 14/19] arm64: entry: handle all vectors with C Mark Rutland
2021-05-21 15:59   ` Joey Gouly
2021-05-21 16:41     ` Mark Rutland
2021-05-19 12:38 ` [PATCH v2 15/19] arm64: entry: split bad stack entry Mark Rutland
2021-05-25 11:25   ` Joey Gouly
2021-05-19 12:38 ` [PATCH v2 16/19] arm64: entry: split SDEI entry Mark Rutland
2021-05-25 11:49   ` Joey Gouly
2021-05-19 12:39 ` [PATCH v2 17/19] arm64: entry: make NMI entry/exit functions static Mark Rutland
2021-05-21 17:21   ` Joey Gouly
2021-05-19 12:39 ` [PATCH v2 18/19] arm64: entry: don't instrument entry code with KCOV Mark Rutland
2021-05-19 12:39 ` [PATCH v2 19/19] arm64: idle: don't instrument idle " Mark Rutland

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