Problem 2.
When I start trying to make a fast solution and try to read registers and some
info from low level physical seL4 thread using seL4_TCB_ReadRegisters I found
that:
In returned successfully data rip register is always 0 for current thread, tcb
selector myself.native_thread().tcb_sel also 0, and rsp = 0x13!
Probably I can’t read myself?
Seems that I found answer in the seL4 code. They do not allow ReadReginster
from myself:
In file object/tcb.c
exception_t
decodeReadRegisters(cap_t cap, word_t length, bool_t call,
word_t *buffer)
{
…
thread = TCB_PTR(cap_thread_cap_get_capTCBPtr(cap));
if (thread == NODE_STATE(ksCurThread)) {
userError("TCB ReadRegisters: Attempted to read our own registers.");
current_syscall_error.type = seL4_IllegalOperation;
return EXCEPTION_SYSCALL_ERROR;
}
Seems that this is my fault (while this is not anyhow specified in the docs,
only some innuendo about stopped thread read)
So, the function used from library seL4_TCB_ReadRegisters incorrectly return 0
- everything is ok while it is not.
Also seems that seL4_TCB_WriteRegisters do not work in such conditions as well
- it return without errors and not changing rip to new function specified in
appropriate field …
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