66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
#include "master.hpp"
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namespace factor
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{
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void factor_vm::dispatch_signal_handler(cell *sp, cell *pc, cell handler)
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{
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if (!code->seg->in_segment_p(*pc) || *sp < ctx->callstack_seg->start + stack_reserved)
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{
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/* Fault came from foreign code or a callstack overflow, or we don't
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have enough callstack room to try the resumable handler. Cut the
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callstack down to the shallowest Factor stack frame that leaves room for
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the signal handler to do its thing, and launch the handler without going
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through the resumable subprimitive. */
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signal_resumable = false;
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void *frame_top = (void*)ctx->callstack_top;
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while(frame_top < ctx->callstack_bottom
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&& (cell)frame_top < ctx->callstack_seg->start + stack_reserved)
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{
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frame_top = frame_predecessor(frame_top);
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}
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*sp = (cell)frame_top;
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ctx->callstack_top = frame_top;
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*pc = handler;
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} else {
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signal_resumable = true;
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// Fault came from Factor, and we've got a good callstack. Route the signal
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// handler through the resumable signal handler subprimitive.
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cell offset = *sp % 16;
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signal_handler_addr = handler;
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tagged<word> handler_word = tagged<word>(special_objects[SIGNAL_HANDLER_WORD]);
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/* True stack frames are always 16-byte aligned. Leaf procedures
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that don't create a stack frame will be out of alignment by sizeof(cell)
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bytes. */
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/* On architectures with a link register we would have to check for leafness
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by matching the PC to a word. We should also use FRAME_RETURN_ADDRESS instead
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of assuming the stack pointer is the right place to put the resume address. */
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if (offset == 0)
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{
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cell newsp = *sp - sizeof(cell);
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*sp = newsp;
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*(cell*)newsp = *pc;
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}
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else if (offset == 16 - sizeof(cell))
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{
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// Make a fake frame for the leaf procedure
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FACTOR_ASSERT(code->code_block_for_address(*pc) != NULL);
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cell newsp = *sp - LEAF_FRAME_SIZE;
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*(cell*)newsp = *pc;
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*sp = newsp;
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handler_word = tagged<word>(special_objects[LEAF_SIGNAL_HANDLER_WORD]);
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}
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else
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FACTOR_ASSERT(false);
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*pc = (cell)handler_word->entry_point;
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}
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}
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}
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