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go/src/runtime/sys_nacl_arm.s
Austin Clements f5d494bbdf runtime: ensure GC sees type-safe memory on weak machines 
Currently its possible for the garbage collector to observe
uninitialized memory or stale heap bitmap bits on weakly ordered
architectures such as ARM and PPC. On such architectures, the stores
that zero newly allocated memory and initialize its heap bitmap may
move after a store in user code that makes the allocated object
observable by the garbage collector.

To fix this, add a "publication barrier" (also known as an "export
barrier") before returning from mallocgc. This is a store/store
barrier that ensures any write done by user code that makes the
returned object observable to the garbage collector will be ordered
after the initialization performed by mallocgc. No barrier is
necessary on the reading side because of the data dependency between
loading the pointer and loading the contents of the object.

Fixes one of the issues raised in #9984.

Change-Id: Ia3d96ad9c5fc7f4d342f5e05ec0ceae700cd17c8
Reviewed-on: https://go-review.googlesource.com/11083
Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Martin Capitanio <capnm9@gmail.com>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-06-19 15:29:50 +00:00

332 lines
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ArmAsm
Raw Blame History

// Copyright 2014 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 "go_asm.h"
#include "go_tls.h"
#include "textflag.h"
#include "syscall_nacl.h"
#define NACL_SYSCALL(code) \
MOVW $(0x10000 + ((code)<<5)), R8; BL (R8)
TEXT runtime·exit(SB),NOSPLIT,$0
MOVW code+0(FP), R0
NACL_SYSCALL(SYS_exit)
RET
TEXT runtime·exit1(SB),NOSPLIT,$0
MOVW code+0(FP), R0
NACL_SYSCALL(SYS_thread_exit)
RET
TEXT runtime·open(SB),NOSPLIT,$0
MOVW name+0(FP), R0
MOVW name+0(FP), R1
MOVW name+0(FP), R2
NACL_SYSCALL(SYS_open)
MOVW R0, ret+12(FP)
RET
TEXT runtime·closefd(SB),NOSPLIT,$0
MOVW fd+0(FP), R0
NACL_SYSCALL(SYS_close)
MOVW R0, ret+4(FP)
RET
TEXT runtime·read(SB),NOSPLIT,$0
MOVW fd+0(FP), R0
MOVW p+4(FP), R1
MOVW n+8(FP), R2
NACL_SYSCALL(SYS_read)
MOVW R0, ret+12(FP)
RET
// func naclWrite(fd int, b []byte) int
TEXT syscall·naclWrite(SB),NOSPLIT,$0
MOVW arg1+0(FP), R0
MOVW arg2+4(FP), R1
MOVW arg3+8(FP), R2
NACL_SYSCALL(SYS_write)
MOVW R0, ret+16(FP)
RET
TEXT runtime·write(SB),NOSPLIT,$0
MOVW fd+0(FP), R0
MOVW p+4(FP), R1
MOVW n+8(FP), R2
NACL_SYSCALL(SYS_write)
MOVW R0, ret+12(FP)
RET
TEXT runtime·nacl_exception_stack(SB),NOSPLIT,$0
MOVW p+0(FP), R0
MOVW size+4(FP), R1
NACL_SYSCALL(SYS_exception_stack)
MOVW R0, ret+8(FP)
RET
TEXT runtime·nacl_exception_handler(SB),NOSPLIT,$0
MOVW fn+0(FP), R0
MOVW arg+4(FP), R1
NACL_SYSCALL(SYS_exception_handler)
MOVW R0, ret+8(FP)
RET
TEXT runtime·nacl_sem_create(SB),NOSPLIT,$0
MOVW flag+0(FP), R0
NACL_SYSCALL(SYS_sem_create)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_sem_wait(SB),NOSPLIT,$0
MOVW sem+0(FP), R0
NACL_SYSCALL(SYS_sem_wait)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_sem_post(SB),NOSPLIT,$0
MOVW sem+0(FP), R0
NACL_SYSCALL(SYS_sem_post)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_mutex_create(SB),NOSPLIT,$0
MOVW flag+0(FP), R0
NACL_SYSCALL(SYS_mutex_create)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_mutex_lock(SB),NOSPLIT,$0
MOVW mutex+0(FP), R0
NACL_SYSCALL(SYS_mutex_lock)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_mutex_trylock(SB),NOSPLIT,$0
MOVW mutex+0(FP), R0
NACL_SYSCALL(SYS_mutex_trylock)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_mutex_unlock(SB),NOSPLIT,$0
MOVW mutex+0(FP), R0
NACL_SYSCALL(SYS_mutex_unlock)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_cond_create(SB),NOSPLIT,$0
MOVW flag+0(FP), R0
NACL_SYSCALL(SYS_cond_create)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_cond_wait(SB),NOSPLIT,$0
MOVW cond+0(FP), R0
MOVW n+4(FP), R1
NACL_SYSCALL(SYS_cond_wait)
MOVW R0, ret+8(FP)
RET
TEXT runtime·nacl_cond_signal(SB),NOSPLIT,$0
MOVW cond+0(FP), R0
NACL_SYSCALL(SYS_cond_signal)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_cond_broadcast(SB),NOSPLIT,$0
MOVW cond+0(FP), R0
NACL_SYSCALL(SYS_cond_broadcast)
MOVW R0, ret+4(FP)
RET
TEXT runtime·nacl_cond_timed_wait_abs(SB),NOSPLIT,$0
MOVW cond+0(FP), R0
MOVW lock+4(FP), R1
MOVW ts+8(FP), R2
NACL_SYSCALL(SYS_cond_timed_wait_abs)
MOVW R0, ret+12(FP)
RET
TEXT runtime·nacl_thread_create(SB),NOSPLIT,$0
MOVW fn+0(FP), R0
MOVW stk+4(FP), R1
MOVW tls+8(FP), R2
MOVW xx+12(FP), R3
NACL_SYSCALL(SYS_thread_create)
MOVW R0, ret+16(FP)
RET
TEXT runtime·mstart_nacl(SB),NOSPLIT,$0
MOVW 0(R9), R0 // TLS
MOVW -8(R0), R1 // g
MOVW -4(R0), R2 // m
MOVW R2, g_m(R1)
MOVW R1, g
B runtime·mstart(SB)
TEXT runtime·nacl_nanosleep(SB),NOSPLIT,$0
MOVW ts+0(FP), R0
MOVW extra+4(FP), R1
NACL_SYSCALL(SYS_nanosleep)
MOVW R0, ret+8(FP)
RET
TEXT runtime·osyield(SB),NOSPLIT,$0
NACL_SYSCALL(SYS_sched_yield)
RET
TEXT runtime·mmap(SB),NOSPLIT,$8
MOVW addr+0(FP), R0
MOVW n+4(FP), R1
MOVW prot+8(FP), R2
MOVW flags+12(FP), R3
MOVW fd+16(FP), R4
// arg6:offset should be passed as a pointer (to int64)
MOVW off+20(FP), R5
MOVW R5, 4(R13)
MOVW $0, R6
MOVW R6, 8(R13)
MOVW $4(R13), R5
MOVM.DB.W [R4,R5], (R13) // arg5 and arg6 are passed on stack
NACL_SYSCALL(SYS_mmap)
MOVM.IA.W (R13), [R4, R5]
CMP $-4095, R0
RSB.HI $0, R0
MOVW R0, ret+24(FP)
RET
TEXT time·now(SB),NOSPLIT,$16
MOVW $0, R0 // real time clock
MOVW $4(R13), R1
NACL_SYSCALL(SYS_clock_gettime)
MOVW 4(R13), R0 // low 32-bit sec
MOVW 8(R13), R1 // high 32-bit sec
MOVW 12(R13), R2 // nsec
MOVW R0, sec+0(FP)
MOVW R1, sec+4(FP)
MOVW R2, sec+8(FP)
RET
TEXT syscall·now(SB),NOSPLIT,$0
B time·now(SB)
TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
MOVW arg1+0(FP), R0
MOVW arg2+4(FP), R1
NACL_SYSCALL(SYS_clock_gettime)
MOVW R0, ret+8(FP)
RET
// int64 nanotime(void) so really
// void nanotime(int64 *nsec)
TEXT runtime·nanotime(SB),NOSPLIT,$16
MOVW $0, R0 // real time clock
MOVW $4(R13), R1
NACL_SYSCALL(SYS_clock_gettime)
MOVW 4(R13), R0 // low 32-bit sec
MOVW 8(R13), R1 // high 32-bit sec (ignored for now)
MOVW 12(R13), R2 // nsec
MOVW $1000000000, R3
MULLU R0, R3, (R1, R0)
MOVW $0, R4
ADD.S R2, R0
ADC R4, R1
MOVW R0, ret_lo+0(FP)
MOVW R1, ret_hi+4(FP)
RET
TEXT runtime·sigtramp(SB),NOSPLIT,$80
// load g from thread context
MOVW $ctxt+-4(FP), R0
MOVW (16*4+10*4)(R0), g
// check that g exists
CMP $0, g
BNE 4(PC)
MOVW $runtime·badsignal2(SB), R11
BL (R11)
RET
// save g
MOVW g, R3
MOVW g, 20(R13)
// g = m->gsignal
MOVW g_m(g), R8
MOVW m_gsignal(R8), g
// copy arguments for call to sighandler
MOVW $11, R0
MOVW R0, 4(R13) // signal
MOVW $0, R0
MOVW R0, 8(R13) // siginfo
MOVW $ctxt+-4(FP), R0
MOVW R0, 12(R13) // context
MOVW R3, 16(R13) // g
BL runtime·sighandler(SB)
// restore g
MOVW 20(R13), g
// Enable exceptions again.
NACL_SYSCALL(SYS_exception_clear_flag)
// Restore registers as best we can. Impossible to do perfectly.
// See comment in sys_nacl_386.s for extended rationale.
MOVW $ctxt+-4(FP), R1
ADD $64, R1
MOVW (0*4)(R1), R0
MOVW (2*4)(R1), R2
MOVW (3*4)(R1), R3
MOVW (4*4)(R1), R4
MOVW (5*4)(R1), R5
MOVW (6*4)(R1), R6
MOVW (7*4)(R1), R7
MOVW (8*4)(R1), R8
// cannot write to R9
MOVW (10*4)(R1), g
MOVW (11*4)(R1), R11
MOVW (12*4)(R1), R12
MOVW (13*4)(R1), R13
MOVW (14*4)(R1), R14
MOVW (15*4)(R1), R1
B (R1)
nog:
MOVW $0, R0
RET
TEXT runtime·nacl_sysinfo(SB),NOSPLIT,$16
RET
// func getRandomData([]byte)
TEXT runtime·getRandomData(SB),NOSPLIT,$0-12
MOVW buf+0(FP), R0
MOVW len+4(FP), R1
NACL_SYSCALL(SYS_get_random_bytes)
RET
TEXT runtime·casp1(SB),NOSPLIT,$0
B runtime·cas(SB)
// This is only valid for ARMv6+, however, NaCl/ARM is only defined
// for ARMv7A anyway.
// bool armcas(int32 *val, int32 old, int32 new)
// AtomiBLy:
// if(*val == old){
// *val = new;
// return 1;
// }else
// return 0;
TEXT runtime·cas(SB),NOSPLIT,$0
B runtime·armcas(SB)
// Likewise, this is only valid for ARMv7+, but that's okay.
TEXT ·publicationBarrier(SB),NOSPLIT,$-4-0
B runtime·armPublicationBarrier(SB)
TEXT runtime·read_tls_fallback(SB),NOSPLIT,$-4
WORD $0xe7fedef0 // NACL_INSTR_ARM_ABORT_NOW (UDF #0xEDE0)
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