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arm64: entry: improve bad_mode()

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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 decoded 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 somewhat 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 bad_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>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-13-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Mark Rutland 2021-06-07 10:46:16 +01:00 committed by Will Deacon
parent cbed5f8d3f
commit ca0c2647f5
1 changed files with 16 additions and 15 deletions
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31
arch/arm64/kernel/entry-common.c
View file

@ -157,10 +157,21 @@ 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.
*/
static void noinstr __panic_unhandled(struct pt_regs *regs, const char *vector,
unsigned int esr)
{
arm64_enter_nmi(regs);
console_verbose();
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("Unhandled exception");
}
asmlinkage void noinstr bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
{
const char *handler[] = {
@ -170,19 +181,9 @@ asmlinkage void noinstr bad_mode(struct pt_regs *regs, int reason, unsigned int
"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,
esr_get_class_string(esr));
__show_regs(regs);
panic("bad mode");
__panic_unhandled(regs, handler[reason], esr);
}
#ifdef CONFIG_ARM64_ERRATUM_1463225
static DEFINE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa);