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SubjectRe: [PATCH v5 05/16] ARM: use a function table for determining instruction interpreter action
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On Thu, 2014-01-23 at 15:05 -0500, David Long wrote:
> From: "David A. Long" <dave.long@linaro.org>
>
> Make the instruction interpreter call back to semantic action functions
> through a function pointer array provided by the invoker. The interpreter
> decodes the instructions into groups and uses the group number to index
> into the supplied array. kprobes and uprobes code will each supply their
> own array of functions.
>
> Signed-off-by: David A. Long <dave.long@linaro.org>
> ---

[...]

> --- a/arch/arm/kernel/probes.c
> +++ b/arch/arm/kernel/probes.c
> @@ -378,10 +378,11 @@ static const int decode_struct_sizes[NUM_DECODE_TYPES] = {
> */
> int __kprobes
> kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi,
> - const union decode_item *table, bool thumb)
> + const union decode_item *table, bool thumb,
> + const union decode_action *actions)
> {
> - const struct decode_header *h = (struct decode_header *)table;
> - const struct decode_header *next;
> + struct decode_header *h = (struct decode_header *)table;
> + struct decode_header *next;

The decode tables are fixed structures which nothing should want to
modify, so I think the const's above should be kept. I believe that
you've had to resort to changing them because the following typedef
lacks a 'const' on the final argument....

[...]
> diff --git a/arch/arm/kernel/probes.h b/arch/arm/kernel/probes.h
> index c610fa9..81b6e61 100644
[...]
>
> +typedef enum kprobe_insn (probes_custom_decode_t)(kprobe_opcode_t,
> + struct arch_specific_insn *,
> + struct decode_header *);
> +

Adding 'const' above will also have the knock on effect of requiring
const on all the 'custom decode' functions as well.

--
Tixy



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