Most buffers that MPS deals with are small and representable
with integer types of width 16-bit or more.
For highly memory constrained systems, it is therefore a potential
for significant memory savings to use 16-bit types for buffer sizes
throughout MPS.
In prepraration for this, this commit introduces typdefs
```
mbedtls_mps_size_t
mbedtls_mps_stored_size_t
```
for buffer sizes in the MPS implementation and the MPS structures,
respectively.
So far, those MUST be defined as `size_t`: While an effort has been made
to write most of MPS code in terms of `mbedtls_mps_[stored_]size_t` in a
way that would allow narrower types, those aren't yet supported. Still,
we retain the typedefs in order to avoid unnecessary rewriting of a large
body of the MPS codebase.
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
MPS' tracing module uses four macros:
1) TRACE( type, fmt, ... )
This acts like `printf( fmt, ... )` but also allows
the specification of a type of trace output (comment,
warning, error, ...)
2) TRACE_INIT
This acts like TRACE() but increases the level of
indentation. It will be used at the beginning of
function calls.
3) RETURN( val )
Equivalent to `return( val )` plus a decrement in the
level of indentation. This should be used at the end of
functions that have been started with TRACE_INIT.
4) TRACE_END
This combines a trace output with a decrement of the
level of indentation. It's necessary prior to leaving
functions which have been started with TRACE_INIT
but which don't have a return value.
This commit defines those macros as no-op dummies in
`library/mps/trace.h` for now.
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit adds an MPS-specific compile-time option
`MBEDTLS_MPS_TRACE` to the internal MPS header `mps/common.h`.
So far -- this may need revisiting -- MPS comes with its own
internal tracing module which allows to track the operation of
MPS' various layers for the purpose of understanding of it workings
as well as for debugging.
The reasons for the introduction of a module separate from SSL debug
are the following:
1) The SSL debug module requires an SSL context to function because
debug callbacks are part of the runtime configuration of the SSL
module.
The MPS tracing module, in contrast, is not supposed to be used
in production environments, and there is no need for a runtime
configuration. Instead, a compile-time defined tracing callback
is used.
2) In the interest of modularity, MPS' tracing module shouldn't
require having an SSL context around.
3) Purely visually, MPS' tracing module adds support for indentation
according to call-depth and coloring according to which module is
being used, which makes it very useful for what's going on; however,
those features aren't available in the SSL debug module (and they
shouldn't be).
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit adds the compile-time option MBEDTLS_MPS_ENABLE_ASSERTIONS
which controls the presence of runtime assertions in MPS code.
See the documentation in the header for more information.
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
This commit introduces the internal MPS header `mps/common.h`
which will subsequently be populated with MPS-specific compile-time
options and helper macros. For now, it's a stub.
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
