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Patrick Steinhardt
887f98f0db
Currently, all platforms will set up their heap on initialization of the platform code. While this works mostly fine, it poses some limitations on memory management on us. Most notably, allocating big chunks of memory in the gigabyte range would require us to pre-request this many bytes from the firmware and add it to the heap from the beginning on some platforms like EFI. As this isn't needed for most configurations, it is inefficient and may even negatively impact some usecases when, e.g., chainloading. Nonetheless, allocating big chunks of memory is required sometimes, where one example is the upcoming support for the Argon2 key derival function in LUKS2. In order to avoid pre-allocating big chunks of memory, this commit implements a runtime mechanism to add more pages to the system. When a given allocation cannot be currently satisfied, we'll call a given callback set up by the platform's own memory management subsystem, asking it to add a memory area with at least "n" bytes. If this succeeds, we retry searching for a valid memory region, which should now succeed. If this fails, we try asking for "n" bytes, possibly spread across multiple regions, in hopes that region merging means that we end up with enough memory for things to work out. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Daniel Axtens <dja@axtens.net> Tested-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com> Tested-by: Patrick Steinhardt <ps@pks.im>