1 // kernel-vector.S - Kernel Vector for General Exceptions
2 // $Id: //depot/rel/Cottonwood/Xtensa/OS/xtos/kernel-vector.S#3 $
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26 * General exceptions in kernel vector mode (PS.UM==0) go to this kernel
27 * vector. This kernel vector does very little.
28 * Under normal operation of the single-threaded runtime ("XTOS"), kernel
29 * vectored general exceptions do not occur, so nothing needs to be done.
30 * However when debugging, such as when writing exception and
31 * interrupt handlers, kernel vectored exceptions may occur.
32 * They are usually the sign of a bug, so here we take a breakpoint
33 * (if debug option enabled) or take drastic action (infinite loop)
36 * XTOS does not allow exceptions in interrupt or exception handlers.
37 * If it did, a more elaborate kernel vector handler would be needed.
38 * See the Xtensa Microprocessor Programmer's Guide for an
39 * example of how to implement such a kernel vector handler.
42 #include <xtensa/coreasm.h>
43 #include <xtensa/config/system.h>
45 #include <xtensa/simcall.h>
48 #if XCHAL_HAVE_EXCEPTIONS
50 .begin literal_prefix .KernelExceptionVector
51 .section .KernelExceptionVector.text, "ax"
54 .global _KernelExceptionVector
55 _KernelExceptionVector:
57 1: break 1,0 // unexpected kernel exception
58 # elif defined(SIMULATOR)
59 wsr a2, EXCSAVE1 // save a2 where simulator expects it
60 movi a2, SYS_unhandled_kernel_exc
61 1: simcall // let simulator/debugger report unhandled exception
65 j 1b // infinite loop - unexpected kernel exception
67 .size _KernelExceptionVector, . - _KernelExceptionVector
71 #endif /* XCHAL_HAVE_EXCEPTIONS */