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vm: sketchy signal dispatch from leaf procs

db4
Joe Groff 2011-10-20 22:05:38 -07:00
parent 6e4117035e
commit a374c2da05
3 changed files with 28 additions and 13 deletions
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33
vm/callstack.cpp
View File

@ -24,19 +24,30 @@ void factor_vm::dispatch_signal_handler(cell *sp, cell *pc, cell newpc)
that don't create a stack frame will be out of alignment by sizeof(cell)
bytes. */
cell offset = *sp % 16;
if (offset != 0)
fatal_error("fault in unaligned frame at", *pc);
/* Nonleaf procedure */
cell newsp = *sp - sizeof(cell);
*sp = newsp;
*(cell*)newsp = *pc;
*pc = newpc;
ctx->callstack_top = (stack_frame*)newsp;
/* XXX handle leaf procedure */
if (offset == 0) {
signal_from_leaf = false;
cell newsp = *sp - sizeof(cell);
*sp = newsp;
*(cell*)newsp = *pc;
*pc = newpc;
ctx->callstack_top = (stack_frame*)newsp;
} else if (offset == 16 - sizeof(cell)) {
dispatch_signal_handler_from_leaf(sp, pc, newpc);
} else {
fatal_error("Invalid stack frame during signal handler", *sp);
}
}
void factor_vm::dispatch_signal_handler_from_leaf(cell *sp, cell *pc, cell newpc)
{
/* We should try to conjure a stack frame here, but we may need to deal
with callstack overflows or the GC moving code around.
For now leave the stack untouched so the signal handler returns into
the parent procedure. This will cause things to blow up if the stack
is left unbalanced. */
signal_from_leaf = true;
*pc = newpc;
}
/* We ignore the two topmost frames, the 'callstack' primitive
frame itself, and the frame calling the 'callstack' primitive,

6
vm/errors.cpp
View File

@ -179,9 +179,11 @@ void factor_vm::enqueue_safepoint_sample()
void factor_vm::handle_safepoint()
{
if (signal_from_leaf)
std::cout << "XXX SIGNALED FROM LEAF\n";
if (safepoint_fep) {
std::cout << "Interrupted. Entering low-level debugger...\n";
std::cout << "\n";
std::cout << "Interrupted\n";
factorbug();
code->unguard_safepoint();
safepoint_fep = false;

2
vm/vm.hpp
View File

@ -56,6 +56,7 @@ struct factor_vm
/* Global variables used to pass fault handler state from signal handler
to VM */
bool signal_from_leaf;
cell signal_number;
cell signal_fault_addr;
unsigned int signal_fpu_status;
@ -605,6 +606,7 @@ struct factor_vm
void primitive_callstack_bounds();
template<typename Iterator> void iterate_callstack(context *ctx, Iterator &iterator);
void dispatch_signal_handler(cell *sp, cell *pc, cell newpc);
void dispatch_signal_handler_from_leaf(cell *sp, cell *pc, cell newpc);
template<typename CellA, typename CellB, typename CellC>
void dispatch_signal_handler(CellA *sp, CellB *pc, CellC newpc)