74 lines
1.3 KiB
C++
74 lines
1.3 KiB
C++
#include "context.h"
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#include "../../rust.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <assert.h>
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extern "C" uint32_t CDECL swap_registers(registers_t *oregs,
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registers_t *regs)
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asm ("swap_registers");
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context::context()
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{
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assert((void*)®s == (void*)this);
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}
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void context::swap(context &out)
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{
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swap_registers(&out.regs, ®s);
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}
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void context::call(void *f, void *arg, void *stack) {
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// Get the current context, which we will then modify to call the
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// given function.
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swap(*this);
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// set up the trampoline frame
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uint32_t *sp = (uint32_t *)stack;
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// Shift the stack pointer so the alignment works out right.
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sp = align_down(sp) - 3;
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*--sp = (uint32_t)arg;
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*--sp = 0xdeadbeef;
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regs.esp = (uint32_t)sp;
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regs.eip = (uint32_t)f;
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}
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#if 0
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// This is some useful code to check how the registers struct got
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// layed out in memory.
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int main() {
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registers_t regs;
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printf("Register offsets\n");
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#define REG(r) \
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printf(" %6s: +%ld\n", #r, (intptr_t)®s.r - (intptr_t)®s);
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REG(eax);
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REG(ebx);
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REG(ecx);
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REG(edx);
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REG(ebp);
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REG(esi);
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REG(edi);
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REG(esp);
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REG(cs);
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REG(ds);
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REG(ss);
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REG(es);
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REG(fs);
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REG(gs);
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REG(eflags);
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REG(eip);
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return 0;
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}
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#endif
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