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// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "zasm_GOOS_GOARCH.h"
#include "../../cmd/ld/textflag.h"
#include "syscall_nacl.h"
#define NACL_SYSCALL(code) \
MOVL $(0x10000 + ((code)<<5)), AX; CALL AX
#define NACL_SYSJMP(code) \
MOVL $(0x10000 + ((code)<<5)), AX; JMP AX
TEXT runtime·exit(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_exit)
TEXT runtime·exit1(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_thread_exit)
TEXT runtime·open(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_open)
TEXT runtime·close(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_close)
TEXT runtime·read(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_read)
TEXT syscall·naclWrite(SB), NOSPLIT, $12-16
MOVL arg1+0(FP), DI
MOVL arg2+4(FP), SI
MOVL arg3+8(FP), DX
MOVL DI, 0(SP)
MOVL SI, 4(SP)
MOVL DX, 8(SP)
CALL runtime·write(SB)
MOVL AX, ret+16(FP)
RET
TEXT runtime·write(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_write)
TEXT runtime·nacl_exception_stack(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_exception_stack)
TEXT runtime·nacl_exception_handler(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_exception_handler)
TEXT runtime·nacl_sem_create(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_sem_create)
TEXT runtime·nacl_sem_wait(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_sem_wait)
TEXT runtime·nacl_sem_post(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_sem_post)
TEXT runtime·nacl_mutex_create(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_mutex_create)
TEXT runtime·nacl_mutex_lock(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_mutex_lock)
TEXT runtime·nacl_mutex_trylock(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_mutex_trylock)
TEXT runtime·nacl_mutex_unlock(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_mutex_unlock)
TEXT runtime·nacl_cond_create(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_cond_create)
TEXT runtime·nacl_cond_wait(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_cond_wait)
TEXT runtime·nacl_cond_signal(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_cond_signal)
TEXT runtime·nacl_cond_broadcast(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_cond_broadcast)
TEXT runtime·nacl_cond_timed_wait_abs(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_cond_timed_wait_abs)
TEXT runtime·nacl_thread_create(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_thread_create)
TEXT runtime·mstart_nacl(SB),NOSPLIT,$0
JMP runtime·mstart(SB)
TEXT runtime·nacl_nanosleep(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_nanosleep)
TEXT runtime·osyield(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_sched_yield)
TEXT runtime·mmap(SB),NOSPLIT,$32
MOVL arg1+0(FP), AX
MOVL AX, 0(SP)
MOVL arg2+4(FP), AX
MOVL AX, 4(SP)
MOVL arg3+8(FP), AX
MOVL AX, 8(SP)
MOVL arg4+12(FP), AX
MOVL AX, 12(SP)
MOVL arg5+16(FP), AX
MOVL AX, 16(SP)
MOVL arg6+20(FP), AX
MOVL AX, 24(SP)
MOVL $0, 28(SP)
LEAL 24(SP), AX
MOVL AX, 20(SP)
NACL_SYSCALL(SYS_mmap)
RET
TEXT time·now(SB),NOSPLIT,$20
MOVL $0, 0(SP) // real time clock
LEAL 8(SP), AX
MOVL AX, 4(SP) // timespec
NACL_SYSCALL(SYS_clock_gettime)
MOVL 8(SP), AX // low 32 sec
MOVL 12(SP), CX // high 32 sec
MOVL 16(SP), BX // nsec
// sec is in AX, nsec in BX
MOVL AX, sec+0(FP)
MOVL CX, sec+4(FP)
MOVL BX, nsec+8(FP)
RET
TEXT syscall·now(SB),NOSPLIT,$0
JMP time·now(SB)
TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
NACL_SYSJMP(SYS_clock_gettime)
TEXT runtime·nanotime(SB),NOSPLIT,$20
MOVL $0, 0(SP) // real time clock
LEAL 8(SP), AX
MOVL AX, 4(SP) // timespec
NACL_SYSCALL(SYS_clock_gettime)
MOVL 8(SP), AX // low 32 sec
MOVL 16(SP), BX // nsec
// sec is in AX, nsec in BX
// convert to DX:AX nsec
MOVL $1000000000, CX
MULL CX
ADDL BX, AX
ADCL $0, DX
MOVL ret+0(FP), DI
MOVL AX, 0(DI)
MOVL DX, 4(DI)
RET
TEXT runtime·setldt(SB),NOSPLIT,$8
MOVL addr+4(FP), BX // aka base
ADDL $0x8, BX
MOVL BX, 0(SP)
NACL_SYSCALL(SYS_tls_init)
RET
TEXT runtime·sigtramp(SB),NOSPLIT,$0
get_tls(CX)
// check that m exists
MOVL m(CX), BX
CMPL BX, $0
JNE 6(PC)
MOVL $11, BX
MOVL BX, 0(SP)
MOVL $runtime·badsignal(SB), AX
CALL AX
JMP sigtramp_ret
// save g
MOVL g(CX), DI
MOVL DI, 20(SP)
// g = m->gsignal
MOVL m_gsignal(BX), BX
MOVL BX, g(CX)
// copy arguments for sighandler
MOVL $11, 0(SP) // signal
MOVL $0, 4(SP) // siginfo
LEAL ctxt+4(FP), AX
MOVL AX, 8(SP) // context
MOVL DI, 12(SP) // g
CALL runtime·sighandler(SB)
// restore g
get_tls(CX)
MOVL 20(SP), BX
MOVL BX, g(CX)
sigtramp_ret:
// Enable exceptions again.
NACL_SYSCALL(SYS_exception_clear_flag)
// NaCl has abidcated its traditional operating system responsibility
// and declined to implement 'sigreturn'. Instead the only way to return
// to the execution of our program is to restore the registers ourselves.
// Unfortunately, that is impossible to do with strict fidelity, because
// there is no way to do the final update of PC that ends the sequence
// without either (1) jumping to a register, in which case the register ends
// holding the PC value instead of its intended value or (2) storing the PC
// on the stack and using RET, which imposes the requirement that SP is
// valid and that is okay to smash the word below it. The second would
// normally be the lesser of the two evils, except that on NaCl, the linker
// must rewrite RET into "POP reg; AND $~31, reg; JMP reg", so either way
// we are going to lose a register as a result of the incoming signal.
// Similarly, there is no way to restore EFLAGS; the usual way is to use
// POPFL, but NaCl rejects that instruction. We could inspect the bits and
// execute a sequence of instructions designed to recreate those flag
// settings, but that's a lot of work.
//
// Thankfully, Go's signal handlers never try to return directly to the
// executing code, so all the registers and EFLAGS are dead and can be
// smashed. The only registers that matter are the ones that are setting
// up for the simulated call that the signal handler has created.
// Today those registers are just PC and SP, but in case additional registers
// are relevant in the future (for example DX is the Go func context register)
// we restore as many registers as possible.
//
// We smash BP, because that's what the linker smashes during RET.
//
LEAL ctxt+4(FP), BP
ADDL $64, BP
MOVL 0(BP), AX
MOVL 4(BP), CX
MOVL 8(BP), DX
MOVL 12(BP), BX
MOVL 16(BP), SP
// 20(BP) is saved BP, never to be seen again
MOVL 24(BP), SI
MOVL 28(BP), DI
// 36(BP) is saved EFLAGS, never to be seen again
MOVL 32(BP), BP // saved PC
JMP BP
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