linux-kernel - Re: [PATCH v3 12/16] powerpc/watchpoint: Use builtin ALIGN*() macros

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Date:   Fri, 24 Apr 2020 08:54:14 +0530
From:   Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     mpe@...erman.id.au, mikey@...ling.org, apopple@...ux.ibm.com,
        paulus@...ba.org, npiggin@...il.com,
        naveen.n.rao@...ux.vnet.ibm.com, peterz@...radead.org,
        jolsa@...nel.org, oleg@...hat.com, fweisbec@...il.com,
        mingo@...nel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org,
        Ravi Bangoria <ravi.bangoria@...ux.ibm.com>
Subject: Re: [PATCH v3 12/16] powerpc/watchpoint: Use builtin ALIGN*() macros

Hi Christophe,

>>           max_len = DAWR_MAX_LEN;
>>           /* DAWR region can't cross 512 bytes boundary */
>> -        if ((start_addr >> 9) != (end_addr >> 9))
>> +        if ((start_addr >> 9) != ((end_addr - 1) >> 9))
> 
> What about:
>      if (ALIGN(start_addr, SZ_512M) != ALIGN(end - 1, SZ_512M))

ok.

> 
>>               return -EINVAL;
>>       } else if (IS_ENABLED(CONFIG_PPC_8xx)) {
>>           /* 8xx can setup a range without limitation */
>> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
>> index aab82ab80dfa..06679adac447 100644
>> --- a/arch/powerpc/kernel/process.c
>> +++ b/arch/powerpc/kernel/process.c
>> @@ -800,12 +800,12 @@ static inline int set_breakpoint_8xx(struct arch_hw_breakpoint *brk)
>>       unsigned long lctrl1 = LCTRL1_CTE_GT | LCTRL1_CTF_LT | LCTRL1_CRWE_RW |
>>                      LCTRL1_CRWF_RW;
>>       unsigned long lctrl2 = LCTRL2_LW0EN | LCTRL2_LW0LADC | LCTRL2_SLW0EN;
>> -    unsigned long start_addr = brk->address & ~HW_BREAKPOINT_ALIGN;
>> -    unsigned long end_addr = (brk->address + brk->len - 1) | HW_BREAKPOINT_ALIGN;
>> +    unsigned long start_addr = ALIGN_DOWN(brk->address, HW_BREAKPOINT_SIZE);
>> +    unsigned long end_addr = ALIGN(brk->address + brk->len, HW_BREAKPOINT_SIZE);
>>       if (start_addr == 0)
>>           lctrl2 |= LCTRL2_LW0LA_F;
>> -    else if (end_addr == ~0U)
>> +    else if (end_addr - 1 == ~0U)
> 
> What about:
>      else if (end_addr == 0)

That's better.

Thanks,
Ravi