linux-kernel - Re: [PATCH] powerpc/process: Enhance readability for trap types.

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Date:   Mon, 29 Mar 2021 07:11:29 +0800
From:   Xiongwei Song <sxwjean@...com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        npiggin@...il.com, ravi.bangoria@...ux.ibm.com, mikey@...ling.org,
        aneesh.kumar@...ux.ibm.com, haren@...ux.ibm.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Xiongwei Song <sxwjean@...il.com>
Subject: Re: [PATCH] powerpc/process: Enhance readability for trap types.


> On Mar 28, 2021, at 11:21 PM, Christophe Leroy <christophe.leroy@...roup.eu> wrote:
> 
> 
> 
> Le 28/03/2021 à 16:35, Xiongwei Song a écrit :
>> From: Xiongwei Song <sxwjean@...il.com>
>> Define macros to enhance the code readability on ppc trap types.
> 
> Good idea
> 
>> Signed-off-by: Xiongwei Song <sxwjean@...il.com>
>> ---
>>  arch/powerpc/kernel/process.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
>> index 3231c2df9e26..3bbd3cf353a7 100644
>> --- a/arch/powerpc/kernel/process.c
>> +++ b/arch/powerpc/kernel/process.c
>> @@ -1451,6 +1451,10 @@ static void print_msr_bits(unsigned long val)
>>  #define LAST_VOLATILE	12
>>  #endif
>>  +#define TRAP_MC  0x200 /* Machine Check */
> 
> I think usually we use MCE, so TRAP_MCE would be better

Ok.
> 
>> +#define TRAP_DSI 0x300 /* DSI exception */
>> +#define TRAP_AM  0x600 /* Alignment exception */
> 
> Don't know what AM means. TRAP_ALIGN would be more explicit.

No Problem.
> 
>> +
> 
> The defines should go in a header file, for instance asm/ptrace.h in order to be re-used in other files.

Agree.
> 
> You should do more. You can find other places to improve with:
> 
> git grep "trap ==" arch/powerpc/
> git grep "TRAP(regs) ==" arch/powerpc/

Just ran “git grep”, looks like the work is much bigger than what I imagined.
> 
>>  static void __show_regs(struct pt_regs *regs)
>>  {
>>  	int i, trap;
>> @@ -1465,7 +1469,7 @@ static void __show_regs(struct pt_regs *regs)
>>  	trap = TRAP(regs);
>>  	if (!trap_is_syscall(regs) && cpu_has_feature(CPU_FTR_CFAR))
>>  		pr_cont("CFAR: "REG" ", regs->orig_gpr3);
>> -	if (trap == 0x200 || trap == 0x300 || trap == 0x600) {
>> +	if (trap == TRAP_MC || trap == TRAP_DSI || trap == TRAP_AM) {
>>  		if (IS_ENABLED(CONFIG_4xx) || IS_ENABLED(CONFIG_BOOKE))
>>  			pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar, regs->dsisr);
>>  		else

Thanks for the response. I will send v2.

 Regards,
Xiongwei