185 lines
6.3 KiB
C
185 lines
6.3 KiB
C
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// overlay.h -- Overlay manager header file
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// $Id$
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// Copyright (c) 2013 Tensilica Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#ifndef OVERLAY_H
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#define OVERLAY_H
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#include <xtensa/xtruntime.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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// Define this to turn off overlay support
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#ifdef XT_DISABLE_OVERLAYS
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#define OVERLAY(n)
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#define DECLARE_OVERLAY(n)
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#define xt_overlay_map(ov_id)
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#define xt_overlay_map_async(ov_id) 0
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#define xt_overlay_map_in_progress() 0
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#define xt_overlay_get_id() 0
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#define xt_overlay_get_state(pc) 0
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#define xt_overlay_check_map(pc,ps,ovstate,sp) 0
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#else
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// Shorthand for convenience and portability.
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#define OVERLAY(n) __attribute__((overlay(n)))
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// Structure of the overlay table required by gdb and the overlay
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// manager. Should not be accessed by user code unless overriding
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// the load process.
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struct ovly_table {
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void * vma; // The overlay's mapped address.
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unsigned int size; // The size of the overlay, in bytes.
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void * lma; // The overlay's load address.
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unsigned int mapped; // Non-zero if overlay is currently mapped; zero otherwise.
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};
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// Constructed by the linker. Required for gdb and for the overlay
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// manager. Should not be accessed by user code unless overriding
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// the load process.
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extern struct ovly_table _ovly_table[];
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// Functions.
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void xt_overlay_map(int ov_id);
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int xt_overlay_map_async(int ov_id);
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int xt_overlay_map_in_progress(void);
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unsigned int xt_overlay_get_state(unsigned int pc);
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unsigned int xt_overlay_check_map(unsigned int * pc, unsigned int * ps,
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unsigned int ovstate, unsigned int sp);
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int xt_overlay_start_map(void * dst, void * src, unsigned int len, int ov_id);
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int xt_overlay_is_mapping(int ov_id);
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void xt_overlay_fatal_error(int ov_id);
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// Returns the current overlay ID. If no overlay is mapped or an overlay
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// is in the middle of being mapped, returns -1. Inlined to avoid calling
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// out of overlay (wastes cycles, can end up reading wrong ID on interrupt
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// activity).
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//
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static inline int xt_overlay_get_id(void)
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{
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#pragma always_inline
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extern short _mapping_id;
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extern short _ovly_id;
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int ret;
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unsigned int flags = XTOS_SET_INTLEVEL(15);
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if (_mapping_id >= 0) {
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ret = -1;
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}
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else {
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ret = _ovly_id;
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}
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XTOS_RESTORE_INTLEVEL(flags);
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return ret;
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}
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// The following macros are used to declare numbered overlays and generate
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// the corresponding call stubs. Use as follows:
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//
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// DECLARE_OVERLAY(n)
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//
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// See documentation for more details.
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//#include <xtensa/config/core-isa.h>
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// At this time overlays are not supported without windowing.
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#if defined(__XTENSA_WINDOWED_ABI__)
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#define xstr(x) str(x)
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#define str(x) #x
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// At entry, register a8 holds the return address and a9 holds the target
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// function address. This stub saves a8 on the stack at (SP - 20) which
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// is the only location that is safe for us to use. Then it allocates 32
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// bytes on the stack for working storage, loads the overlay number into
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// a8, and jumps to the common handler. The common handler will make sure
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// that the called function is loaded into memory before calling it.
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// NOTE: we are using the stack area normally reserved for nested functions.
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// This means nested functions cannot be used when overlays are in use.
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#define CALL_IN(num) \
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asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \
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".global _overlay_call_in_" xstr(num) "_\n" \
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".align 4\n" \
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"_overlay_call_in_" xstr(num) "_:\n" \
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"s32e a8, a1, -20\n" \
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"addi a8, a1, -32\n" \
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"movsp a1, a8\n" \
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"movi a8, " xstr(num) "\n" \
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"j _overlay_call_in_common\n" \
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".size _overlay_call_in_" xstr(num) "_, . - _overlay_call_in_" xstr(num) "_\n");
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// The call-out stub first calls the target function, then loads the overlay
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// number into register a14 and jumps to the common handler. The handler will
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// make sure that the caller function is present in memory before returning.
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// Note that registers a10-a13 may contain return values so must be preserved.
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//
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// Because we came here via a call4, the return address is in a4, and the top
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// 2 bits are set to the window increment. We'll restore the top 2 bits of
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// the return address from the called function's address, assuming that both
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// are in the same 1 GB segment. For now this is always true.
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#define CALL_OUT(num) \
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asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \
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".global _overlay_call_out_" xstr(num) "_\n" \
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".align 4\n" \
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"_overlay_call_out_" xstr(num) "_:\n" \
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"slli a4, a4, 2\n" \
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"srli a4, a4, 2\n" \
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"extui a8, a9, 30, 2\n" \
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"slli a8, a8, 30\n" \
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"or a4, a4, a8\n" \
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"callx8 a9\n" \
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"movi a14, " xstr(num) "\n" \
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"j _overlay_call_out_common\n" \
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".size _overlay_call_out_" xstr(num) "_, . - _overlay_call_out_" xstr(num) "_\n");
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// Generate a call-in and a call-out stub for each overlay.
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#define DECLARE_OVERLAY(num) \
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CALL_IN(num) \
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CALL_OUT(num)
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#endif // defined(__XTENSA_WINDOWED_ABI__)
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#endif // XT_DISABLE_OVERLAYS
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#ifdef __cplusplus
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}
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#endif
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#endif // OVERLAY_H
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