From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: mpe@ellerman.id.au, mikey@neuling.org, apopple@linux.ibm.com,
paulus@samba.org, npiggin@gmail.com,
naveen.n.rao@linux.vnet.ibm.com, peterz@infradead.org,
jolsa@kernel.org, oleg@redhat.com, fweisbec@gmail.com,
mingo@kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint
Date: Wed, 1 Apr 2020 11:20:10 +0200 [thread overview]
Message-ID: <78559ff4-c2c3-e652-a906-8f40673b53d6@c-s.fr> (raw)
In-Reply-To: <cb2c250b-c963-45fe-f3b4-879076c495ab@linux.ibm.com>
Le 01/04/2020 à 11:13, Ravi Bangoria a écrit :
>
>
> On 4/1/20 12:20 PM, Christophe Leroy wrote:
>>
>>
>> Le 01/04/2020 à 08:13, Ravi Bangoria a écrit :
>>> Currently we assume that we have only one watchpoint supported by hw.
>>> Get rid of that assumption and use dynamic loop instead. This should
>>> make supporting more watchpoints very easy.
>>>
>>> With more than one watchpoint, exception handler need to know which
>>> DAWR caused the exception, and hw currently does not provide it. So
>>> we need sw logic for the same. To figure out which DAWR caused the
>>> exception, check all different combinations of user specified range,
>>> dawr address range, actual access range and dawrx constrains. For ex,
>>> if user specified range and actual access range overlaps but dawrx is
>>> configured for readonly watchpoint and the instruction is store, this
>>> DAWR must not have caused exception.
>>>
>>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
>>> ---
>>> arch/powerpc/include/asm/processor.h | 2 +-
>>> arch/powerpc/include/asm/sstep.h | 2 +
>>> arch/powerpc/kernel/hw_breakpoint.c | 396 +++++++++++++++++++++------
>>> arch/powerpc/kernel/process.c | 3 -
>>> 4 files changed, 313 insertions(+), 90 deletions(-)
>>>
>>
>> [...]
>>
>>> -static bool
>>> -dar_range_overlaps(unsigned long dar, int size, struct
>>> arch_hw_breakpoint *info)
>>> +static bool dar_user_range_overlaps(unsigned long dar, int size,
>>> + struct arch_hw_breakpoint *info)
>>> {
>>> return ((dar <= info->address + info->len - 1) &&
>>> (dar + size - 1 >= info->address));
>>> }
>>
>> Here and several other places, I think it would be more clear if you
>> could avoid the - 1 :
>>
>> return ((dar < info->address + info->len) &&
>> (dar + size > info->address));
>
> Ok. see below...
>
>>
>>
>>> +static bool dar_in_hw_range(unsigned long dar, struct
>>> arch_hw_breakpoint *info)
>>> +{
>>> + unsigned long hw_start_addr, hw_end_addr;
>>> +
>>> + hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE);
>>> + hw_end_addr = ALIGN(info->address + info->len,
>>> HW_BREAKPOINT_SIZE) - 1;
>>> +
>>> + return ((hw_start_addr <= dar) && (hw_end_addr >= dar));
>>> +}
>>
>> hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE);
>>
>> return ((hw_start_addr <= dar) && (hw_end_addr > dar));
>
> I'm using -1 while calculating end address is to make it
> inclusive. If I don't use -1, the end address points to a
> location outside of actual range, i.e. it's not really an
> end address.
But that's what is done is several places, for instance:
https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/mm/dma-noncoherent.c#L22
https://elixir.bootlin.com/linux/v5.6/source/arch/powerpc/include/asm/book3s/32/kup.h#L92
In several places like this, end is outside of the range. My feeling is
that is helps with readability.
Christophe
next prev parent reply other threads:[~2020-04-01 9:20 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 6:12 [PATCH v2 00/16] powerpc/watchpoint: Preparation for more than one watchpoint Ravi Bangoria
2020-04-01 6:12 ` [PATCH v2 01/16] powerpc/watchpoint: Rename current DAWR macros Ravi Bangoria
2020-04-01 6:12 ` [PATCH v2 02/16] powerpc/watchpoint: Add SPRN macros for second DAWR Ravi Bangoria
2020-04-01 6:12 ` [PATCH v2 03/16] powerpc/watchpoint: Introduce function to get nr watchpoints dynamically Ravi Bangoria
2020-04-01 6:29 ` Christophe Leroy
2020-04-01 6:50 ` Ravi Bangoria
2020-04-01 7:05 ` Christophe Leroy
2020-04-01 6:12 ` [PATCH v2 04/16] powerpc/watchpoint/ptrace: Return actual num of available watchpoints Ravi Bangoria
2020-04-01 6:12 ` [PATCH v2 05/16] powerpc/watchpoint: Provide DAWR number to set_dawr Ravi Bangoria
2020-04-01 7:03 ` Christophe Leroy
2020-04-01 6:12 ` [PATCH v2 06/16] powerpc/watchpoint: Provide DAWR number to __set_breakpoint Ravi Bangoria
2020-04-01 7:03 ` Christophe Leroy
2020-04-01 8:57 ` Ravi Bangoria
2020-04-01 9:11 ` Christophe Leroy
2020-04-01 9:44 ` Christophe Leroy
2020-04-01 6:13 ` [PATCH v2 07/16] powerpc/watchpoint: Get watchpoint count dynamically while disabling them Ravi Bangoria
2020-04-01 6:32 ` Christophe Leroy
2020-04-01 9:19 ` Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 08/16] powerpc/watchpoint: Disable all available watchpoints when !dawr_force_enable Ravi Bangoria
2020-04-01 6:33 ` Christophe Leroy
2020-04-01 9:00 ` Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 09/16] powerpc/watchpoint: Convert thread_struct->hw_brk to an array Ravi Bangoria
2020-04-01 6:43 ` Christophe Leroy
2020-04-01 9:06 ` Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 10/16] powerpc/watchpoint: Use loop for thread_struct->ptrace_bps Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 11/16] powerpc/watchpoint: Introduce is_ptrace_bp() function Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 12/16] powerpc/watchpoint: Use builtin ALIGN*() macros Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint Ravi Bangoria
2020-04-01 6:50 ` Christophe Leroy
2020-04-01 9:13 ` Ravi Bangoria
2020-04-01 9:20 ` Christophe Leroy [this message]
2020-04-01 9:23 ` Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 14/16] powerpc/watchpoint: Don't allow concurrent perf and ptrace events Ravi Bangoria
2020-04-01 6:52 ` Christophe Leroy
2020-04-01 6:13 ` [PATCH v2 15/16] powerpc/watchpoint/xmon: Don't allow breakpoint overwriting Ravi Bangoria
2020-04-01 6:13 ` [PATCH v2 16/16] powerpc/watchpoint/xmon: Support 2nd dawr Ravi Bangoria
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