// overlay.h -- Overlay manager header file // $Id$ // Copyright (c) 2013 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. #ifndef OVERLAY_H #define OVERLAY_H #include #ifdef __cplusplus extern "C" { #endif // Define this to turn off overlay support #ifdef XT_DISABLE_OVERLAYS #define OVERLAY(n) #define DECLARE_OVERLAY(n) #define xt_overlay_map(ov_id) #define xt_overlay_map_async(ov_id) 0 #define xt_overlay_map_in_progress() 0 #define xt_overlay_get_id() 0 #define xt_overlay_get_state(pc) 0 #define xt_overlay_check_map(pc,ps,ovstate,sp) 0 #else // Shorthand for convenience and portability. #define OVERLAY(n) __attribute__((overlay(n))) // Structure of the overlay table required by gdb and the overlay // manager. Should not be accessed by user code unless overriding // the load process. struct ovly_table { void * vma; // The overlay's mapped address. unsigned int size; // The size of the overlay, in bytes. void * lma; // The overlay's load address. unsigned int mapped; // Non-zero if overlay is currently mapped; zero otherwise. }; // Constructed by the linker. Required for gdb and for the overlay // manager. Should not be accessed by user code unless overriding // the load process. extern struct ovly_table _ovly_table[]; // Functions. void xt_overlay_map(int ov_id); int xt_overlay_map_async(int ov_id); int xt_overlay_map_in_progress(void); unsigned int xt_overlay_get_state(unsigned int pc); unsigned int xt_overlay_check_map(unsigned int * pc, unsigned int * ps, unsigned int ovstate, unsigned int sp); int xt_overlay_start_map(void * dst, void * src, unsigned int len, int ov_id); int xt_overlay_is_mapping(int ov_id); void xt_overlay_fatal_error(int ov_id); // Returns the current overlay ID. If no overlay is mapped or an overlay // is in the middle of being mapped, returns -1. Inlined to avoid calling // out of overlay (wastes cycles, can end up reading wrong ID on interrupt // activity). // static inline int xt_overlay_get_id(void) { #pragma always_inline extern short _mapping_id; extern short _ovly_id; int ret; unsigned int flags = XTOS_SET_INTLEVEL(15); if (_mapping_id >= 0) { ret = -1; } else { ret = _ovly_id; } XTOS_RESTORE_INTLEVEL(flags); return ret; } // The following macros are used to declare numbered overlays and generate // the corresponding call stubs. Use as follows: // // DECLARE_OVERLAY(n) // // See documentation for more details. //#include // At this time overlays are not supported without windowing. #if defined(__XTENSA_WINDOWED_ABI__) #define xstr(x) str(x) #define str(x) #x // At entry, register a8 holds the return address and a9 holds the target // function address. This stub saves a8 on the stack at (SP - 20) which // is the only location that is safe for us to use. Then it allocates 32 // bytes on the stack for working storage, loads the overlay number into // a8, and jumps to the common handler. The common handler will make sure // that the called function is loaded into memory before calling it. // NOTE: we are using the stack area normally reserved for nested functions. // This means nested functions cannot be used when overlays are in use. #define CALL_IN(num) \ asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \ ".global _overlay_call_in_" xstr(num) "_\n" \ ".align 4\n" \ "_overlay_call_in_" xstr(num) "_:\n" \ "s32e a8, a1, -20\n" \ "addi a8, a1, -32\n" \ "movsp a1, a8\n" \ "movi a8, " xstr(num) "\n" \ "j _overlay_call_in_common\n" \ ".size _overlay_call_in_" xstr(num) "_, . - _overlay_call_in_" xstr(num) "_\n"); // The call-out stub first calls the target function, then loads the overlay // number into register a14 and jumps to the common handler. The handler will // make sure that the caller function is present in memory before returning. // Note that registers a10-a13 may contain return values so must be preserved. // // Because we came here via a call4, the return address is in a4, and the top // 2 bits are set to the window increment. We'll restore the top 2 bits of // the return address from the called function's address, assuming that both // are in the same 1 GB segment. For now this is always true. #define CALL_OUT(num) \ asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \ ".global _overlay_call_out_" xstr(num) "_\n" \ ".align 4\n" \ "_overlay_call_out_" xstr(num) "_:\n" \ "slli a4, a4, 2\n" \ "srli a4, a4, 2\n" \ "extui a8, a9, 30, 2\n" \ "slli a8, a8, 30\n" \ "or a4, a4, a8\n" \ "callx8 a9\n" \ "movi a14, " xstr(num) "\n" \ "j _overlay_call_out_common\n" \ ".size _overlay_call_out_" xstr(num) "_, . - _overlay_call_out_" xstr(num) "_\n"); // Generate a call-in and a call-out stub for each overlay. #define DECLARE_OVERLAY(num) \ CALL_IN(num) \ CALL_OUT(num) #endif // defined(__XTENSA_WINDOWED_ABI__) #endif // XT_DISABLE_OVERLAYS #ifdef __cplusplus } #endif #endif // OVERLAY_H