diff options
Diffstat (limited to 'src/runtime/asm_386.s')
| -rw-r--r-- | src/runtime/asm_386.s | 60 |
1 files changed, 21 insertions, 39 deletions
diff --git a/src/runtime/asm_386.s b/src/runtime/asm_386.s index 11863fba39..fa3b1be339 100644 --- a/src/runtime/asm_386.s +++ b/src/runtime/asm_386.s @@ -702,25 +702,9 @@ nosave: MOVL AX, ret+8(FP) RET -// cgocallback(void (*fn)(void*), void *frame, uintptr framesize, uintptr ctxt) -// Turn the fn into a Go func (by taking its address) and call -// cgocallback_gofunc. -TEXT runtime·cgocallback(SB),NOSPLIT,$16-16 - LEAL fn+0(FP), AX - MOVL AX, 0(SP) - MOVL frame+4(FP), AX - MOVL AX, 4(SP) - MOVL framesize+8(FP), AX - MOVL AX, 8(SP) - MOVL ctxt+12(FP), AX - MOVL AX, 12(SP) - MOVL $runtime·cgocallback_gofunc(SB), AX - CALL AX - RET - -// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize, uintptr ctxt) +// cgocallback(fn, frame unsafe.Pointer, ctxt uintptr) // See cgocall.go for more details. -TEXT ·cgocallback_gofunc(SB),NOSPLIT,$12-16 +TEXT ·cgocallback(SB),NOSPLIT,$12-12 // Frame size must match commented places below NO_LOCAL_POINTERS // If g is nil, Go did not create the current thread. @@ -738,13 +722,12 @@ TEXT ·cgocallback_gofunc(SB),NOSPLIT,$12-16 CMPL BP, $0 JEQ needm MOVL g_m(BP), BP - MOVL BP, DX // saved copy of oldm + MOVL BP, savedm-4(SP) // saved copy of oldm JMP havem needm: - MOVL $0, 0(SP) MOVL $runtime·needm(SB), AX CALL AX - MOVL 0(SP), DX + MOVL $0, savedm-4(SP) // dropm on return get_tls(CX) MOVL g(CX), BP MOVL g_m(BP), BP @@ -780,34 +763,32 @@ havem: // save that information (m->curg->sched) so we can restore it. // We can restore m->curg->sched.sp easily, because calling // runtime.cgocallbackg leaves SP unchanged upon return. - // To save m->curg->sched.pc, we push it onto the stack. - // This has the added benefit that it looks to the traceback - // routine like cgocallbackg is going to return to that - // PC (because the frame we allocate below has the same - // size as cgocallback_gofunc's frame declared above) - // so that the traceback will seamlessly trace back into - // the earlier calls. - // - // In the new goroutine, 4(SP) holds the saved oldm (DX) register. - // 8(SP) is unused. + // To save m->curg->sched.pc, we push it onto the curg stack and + // open a frame the same size as cgocallback's g0 frame. + // Once we switch to the curg stack, the pushed PC will appear + // to be the return PC of cgocallback, so that the traceback + // will seamlessly trace back into the earlier calls. MOVL m_curg(BP), SI MOVL SI, g(CX) MOVL (g_sched+gobuf_sp)(SI), DI // prepare stack as DI MOVL (g_sched+gobuf_pc)(SI), BP - MOVL BP, -4(DI) - MOVL ctxt+12(FP), CX - LEAL -(4+12)(DI), SP - MOVL DX, 4(SP) - MOVL CX, 0(SP) + MOVL BP, -4(DI) // "push" return PC on the g stack + // Gather our arguments into registers. + MOVL fn+0(FP), AX + MOVL frame+4(FP), BX + MOVL ctxt+8(FP), CX + LEAL -(4+12)(DI), SP // Must match declared frame size + MOVL AX, 0(SP) + MOVL BX, 4(SP) + MOVL CX, 8(SP) CALL runtime·cgocallbackg(SB) - MOVL 4(SP), DX // Restore g->sched (== m->curg->sched) from saved values. get_tls(CX) MOVL g(CX), SI - MOVL 12(SP), BP + MOVL 12(SP), BP // Must match declared frame size MOVL BP, (g_sched+gobuf_pc)(SI) - LEAL (12+4)(SP), DI + LEAL (12+4)(SP), DI // Must match declared frame size MOVL DI, (g_sched+gobuf_sp)(SI) // Switch back to m->g0's stack and restore m->g0->sched.sp. @@ -823,6 +804,7 @@ havem: // If the m on entry was nil, we called needm above to borrow an m // for the duration of the call. Since the call is over, return it with dropm. + MOVL savedm-4(SP), DX CMPL DX, $0 JNE 3(PC) MOVL $runtime·dropm(SB), AX |