| // double-vector.S -- Double Exception Vector |
| // $Id: //depot/rel/Foxhill/dot.8/Xtensa/OS/xtos/double-vector.S#1 $ |
| |
| // Copyright (c) 2000-2004, 2006, 2010 Tensilica Inc. |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining |
| // a copy of this software and associated documentation files (the |
| // "Software"), to deal in the Software without restriction, including |
| // without limitation the rights to use, copy, modify, merge, publish, |
| // distribute, sublicense, and/or sell copies of the Software, and to |
| // permit persons to whom the Software is furnished to do so, subject to |
| // the following conditions: |
| // |
| // The above copyright notice and this permission notice shall be included |
| // in all copies or substantial portions of the Software. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| // SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| |
| #include <xtensa/coreasm.h> |
| #include <xtensa/config/system.h> |
| #ifdef SIMULATOR |
| #include <xtensa/simcall.h> |
| #endif |
| |
| |
| #if XCHAL_HAVE_EXCEPTIONS && defined(XCHAL_DOUBLEEXC_VECTOR_VADDR) |
| |
| /* |
| * This is a very minimalist implementation of the double |
| * exception vector. For XEA2 configurations without a |
| * full MMU, this vector is only expected to be executed |
| * upon fatal errors (exceptions that occur within critical |
| * sections of exception vectors and handlers). |
| * |
| * For configurations with a full MMU (ie. with TLBs and |
| * auto-refill) and the windowed address registers option, |
| * a more complete version of this handler is necessary if: |
| * dynamic page mapping is implemented, and the stack |
| * can ever point to a dynamically mapped area. |
| * In this case, a double exception is a normal occurrence |
| * when a stack access within a window handler causes |
| * a TLB miss exception or other expected MMU fault. |
| * XTOS does not support this scenario, hence a minimalist |
| * double exception vector is sufficient. |
| */ |
| |
| .begin literal_prefix .DoubleExceptionVector |
| .section .DoubleExceptionVector.text, "ax" |
| |
| .align 4 |
| .global _DoubleExceptionVector |
| _DoubleExceptionVector: |
| |
| # if XCHAL_HAVE_DEBUG |
| 1: break 1,4 // unhandled double exception |
| # elif defined(SIMULATOR) |
| wsr.excsave1 a2 // save a2 where simulator expects it |
| movi a2, SYS_unhandled_double_exc |
| 1: simcall // let simulator/debugger report unhandled exception |
| # else |
| 1: |
| # endif |
| j 1b // infinite loop |
| |
| // NOTE: a non-minimalist vector may choose to |
| // process the double exception in the vector itself |
| // (by default, much more space is allocated to double |
| // exception vectors than to most other vectors); |
| // or, to jump to a double exception handler located |
| // elsewhere. If only the normal case of double |
| // exceptions occurring within a window handler is |
| // being handled, then it is safe to use EXCSAVE_1 to |
| // do this jump (window handlers don't use EXCSAVE_1). |
| // For example: |
| // |
| // wsr.excsave1 a0 |
| // movi a0, _DoubleExceptionFromVector |
| // jx a0 |
| // |
| // .text |
| // .align 4 |
| // .global _DoubleExceptionFromVector |
| //_DoubleExceptionFromVector: |
| // ... |
| |
| |
| .size _DoubleExceptionVector, . - _DoubleExceptionVector |
| .text |
| .end literal_prefix |
| |
| #endif /* have double exceptions */ |
| |