[PATCH 4/7] arm64: decode ESR_ELx.EC when reporting exceptions

[Christoffer Dall]

On Wed, Jan 07, 2015 at 12:04:17PM +0000, Mark Rutland wrote:
> To aid the developer when something triggers an unexpected exception,
> decode the ESR_ELx.EC field when logging an ESR_ELx value. This doesn't
> tell the developer the specifics of the exception encoded in the
> remaining IL and ISS bits, but it can be helpful to distinguish between
> exception classes (e.g. SError and a data abort) without having to
> manually decode the field, which can be tiresome.
> 
> Signed-off-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Christoffer Dall <christoffer.dall at linaro.org>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Cc: Peter Maydell <peter.maydell at linaro.org>
> Cc: Will Deacon <will.deacon at arm.com>
> ---
>  arch/arm64/include/asm/esr.h |  6 ++++++
>  arch/arm64/kernel/traps.c    | 50 ++++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 54 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/esr.h b/arch/arm64/include/asm/esr.h
> index 19492e1..7669a7a 100644
> --- a/arch/arm64/include/asm/esr.h
> +++ b/arch/arm64/include/asm/esr.h
> @@ -96,4 +96,10 @@
>  #define ESR_ELx_COND_MASK	(UL(0xF) << ESR_ELx_COND_SHIFT)
>  #define ESR_ELx_WFx_ISS_WFE	(UL(1) << 0)
>  
> +#ifndef __ASSEMBLY__
> +#include <asm/types.h>
> +
> +const char *esr_get_class_string(u32 esr);
> +#endif /* __ASSEMBLY */
> +
>  #endif /* __ASM_ESR_H */
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 0a801e3..1ef2940 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -33,6 +33,7 @@
>  
>  #include <asm/atomic.h>
>  #include <asm/debug-monitors.h>
> +#include <asm/esr.h>
>  #include <asm/traps.h>
>  #include <asm/stacktrace.h>
>  #include <asm/exception.h>
> @@ -373,6 +374,51 @@ asmlinkage long do_ni_syscall(struct pt_regs *regs)
>  	return sys_ni_syscall();
>  }
>  
> +static const char *esr_class_str[] = {
> +	[0 ... ESR_ELx_EC_MAX]		= "UNRECOGNIZED EC",
> +	[ESR_ELx_EC_UNKNOWN]		= "Unknown/Uncategorized",
> +	[ESR_ELx_EC_WFx]		= "WFI/WFE",
> +	[ESR_ELx_EC_CP15_32]		= "CP15 MCR/MRC",
> +	[ESR_ELx_EC_CP15_64]		= "CP15 MCRR/MRRC",
> +	[ESR_ELx_EC_CP14_MR]		= "CP14 MCR/MRC",
> +	[ESR_ELx_EC_CP14_LS]		= "CP14 LDC/STC",
> +	[ESR_ELx_EC_FP_ASIMD]		= "ASIMD",
> +	[ESR_ELx_EC_CP10_ID]		= "CP10 MRC/VMRS",
> +	[ESR_ELx_EC_CP14_64]		= "CP14 MCRR/MRRC",
> +	[ESR_ELx_EC_ILL]		= "PSTATE.IL",
> +	[ESR_ELx_EC_SVC32]		= "SVC (AArch32)",
> +	[ESR_ELx_EC_HVC32]		= "HVC (AArch32)",
> +	[ESR_ELx_EC_SMC32]		= "SMC (AArch32)",
> +	[ESR_ELx_EC_SVC64]		= "SVC (AArch64)",
> +	[ESR_ELx_EC_HVC64]		= "HVC (AArch64)",
> +	[ESR_ELx_EC_SMC64]		= "SMC (AArch64)",
> +	[ESR_ELx_EC_SYS64]		= "MSR/MRS (AArch64)",
> +	[ESR_ELx_EC_IMP_DEF]		= "EL3 IMP DEF",
> +	[ESR_ELx_EC_IABT_LOW]		= "IABT (lower EL)",
> +	[ESR_ELx_EC_IABT_CUR]		= "IABT (current EL)",
> +	[ESR_ELx_EC_PC_ALIGN]		= "PC Alignment",
> +	[ESR_ELx_EC_DABT_LOW]		= "DABT (lower EL)",
> +	[ESR_ELx_EC_DABT_CUR]		= "DABT (current EL)",
> +	[ESR_ELx_EC_SP_ALIGN]		= "SP Alignment",
> +	[ESR_ELx_EC_FP_EXC32]		= "FP (AArch32)",
> +	[ESR_ELx_EC_FP_EXC64]		= "FP (AArch64)",
> +	[ESR_ELx_EC_SERROR]		= "SError",
> +	[ESR_ELx_EC_BREAKPT_LOW]	= "Breakpoint (lower EL)",
> +	[ESR_ELx_EC_BREAKPT_CUR]	= "Breakpoint (current EL)",
> +	[ESR_ELx_EC_SOFTSTP_LOW]	= "Software Step (lower EL)",
> +	[ESR_ELx_EC_SOFTSTP_CUR]	= "Software Step (current EL)",
> +	[ESR_ELx_EC_WATCHPT_LOW]	= "Watchpoint (lower EL)",
> +	[ESR_ELx_EC_WATCHPT_CUR]	= "Watchpoint (current EL)",
> +	[ESR_ELx_EC_BKPT32]		= "BKPT (AArch32)",
> +	[ESR_ELx_EC_VECTOR32]		= "Vector catch (AArch32)",
> +	[ESR_ELx_EC_BRK64]		= "BRK (AArch64)",
> +};
> +
> +const char *esr_get_class_string(u32 esr)
> +{
> +	return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
> +}
> +
>  /*
>   * bad_mode handles the impossible case in the exception vector.
>   */
> @@ -382,8 +428,8 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
>  	void __user *pc = (void __user *)instruction_pointer(regs);
>  	console_verbose();
>  
> -	pr_crit("Bad mode in %s handler detected, code 0x%08x\n",
> -		handler[reason], esr);
> +	pr_crit("Bad mode in %s handler detected, code 0x%08x -- %s\n",
> +		handler[reason], esr, esr_get_class_string(esr));
>  	__show_regs(regs);
>  
>  	info.si_signo = SIGILL;
> -- 
> 1.9.1
> 

Reviewed-by: Christoffer Dall <christoffer.dall at linaro.org>