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SubjectRe: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint
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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));


>
> +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));

Christophe

> +
> +static bool dar_hw_range_overlaps(unsigned long dar, int size,
> + 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 ((dar <= hw_end_addr) && (dar + size - 1 >= hw_start_addr));
> +}

Same

Christophe

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