Secure Modules

sm common code

sm modules are loaded to 0x80B000, then code from that addr is executed.

There is a lot of common code shared between sm: entry, cmd handler, cmd setup, etc

Entry

This is the first code executed in sm. It's located at 0x80B000. It does the following:

• Get random value (stack cookie?)
• call_ctors()
• sm_main()
• call_dtors()
• syscall 1: Unload
• while(1) sleep()

call_ctors/call_dtors

These just call function pointers, basically libc_init_array.

sm_main

It has a memory pool allocated on stack. It's filled with structures for command handlers. Then, it calls main_loop.

main_loop

This uses syscall 4 (RegisterIrqHandler) to register a common handler for incoming commands (cmd_handler). Then it loops while sm is "active". Then it sets handler for commands = null pointer.

cmd_handler

This is the common handler for all incoming commands. It reads paddr from 0xE0000014 and ANDs it with 1 to check validity. It checks that size is valid (>= 0x40 and < 0x1000), copies command buffer into private f00d memory and executes an appropriate command handler.