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runtime: use a C function to call mmap

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The final argument to mmap, of type off_t, varies.
In CL 445375 we changed it to always use the C off_t type,
but that broke 32-bit big-endian Linux systems.  On those systems,
using the C off_t type requires calling the mmap64 function.
In C this is automatically handled by the <sys/mman.h> file.
In Go, we would have to change the magic //extern comment to
call mmap64 when appropriate.  Rather than try to get that right,
we instead go through a C function that uses C implicit type
conversions to pick the right type.

Fixes PR go/110297

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/504415
This commit is contained in:
Ian Lance Taylor 2023-06-19 14:57:54 -07:00
parent 0be3a051c0
commit efecb298d8
6 changed files with 39 additions and 16 deletions
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2
gcc/go/gofrontend/MERGE
View file

@ -1,4 +1,4 @@
a3a3c3a2d1bc6a8ca51b302d08c94ef27cdd8f0f
6a1d165c2218cd127ee937a1f45599075762f716
The first line of this file holds the git revision number of the last
merge done from the gofrontend repository.

1
libgo/Makefile.am
View file

@ -462,6 +462,7 @@ runtime_files = \
runtime/go-memclr.c \
runtime/go-memmove.c \
runtime/go-memequal.c \
runtime/go-mmap.c \
runtime/go-nanotime.c \
runtime/go-now.c \
runtime/go-nosys.c \

22
libgo/Makefile.in
View file

@ -246,15 +246,15 @@ am__objects_4 = runtime/aeshash.lo runtime/go-assert.lo \
runtime/go-construct-map.lo runtime/go-ffi.lo \
runtime/go-fieldtrack.lo runtime/go-matherr.lo \
runtime/go-memclr.lo runtime/go-memmove.lo \
runtime/go-memequal.lo runtime/go-nanotime.lo \
runtime/go-now.lo runtime/go-nosys.lo runtime/go-strerror.lo \
runtime/go-reflect-call.lo runtime/go-setenv.lo \
runtime/go-signal.lo runtime/go-unsafe-pointer.lo \
runtime/go-unsetenv.lo runtime/go-unwind.lo \
runtime/go-varargs.lo runtime/env_posix.lo runtime/panic.lo \
runtime/print.lo runtime/proc.lo runtime/runtime_c.lo \
runtime/stack.lo runtime/yield.lo $(am__objects_2) \
$(am__objects_3)
runtime/go-memequal.lo runtime/go-mmap.lo \
runtime/go-nanotime.lo runtime/go-now.lo runtime/go-nosys.lo \
runtime/go-strerror.lo runtime/go-reflect-call.lo \
runtime/go-setenv.lo runtime/go-signal.lo \
runtime/go-unsafe-pointer.lo runtime/go-unsetenv.lo \
runtime/go-unwind.lo runtime/go-varargs.lo \
runtime/env_posix.lo runtime/panic.lo runtime/print.lo \
runtime/proc.lo runtime/runtime_c.lo runtime/stack.lo \
runtime/yield.lo $(am__objects_2) $(am__objects_3)
am_libgo_llgo_la_OBJECTS = $(am__objects_4)
libgo_llgo_la_OBJECTS = $(am_libgo_llgo_la_OBJECTS)
AM_V_lt = $(am__v_lt_@AM_V@)
@ -914,6 +914,7 @@ runtime_files = \
runtime/go-memclr.c \
runtime/go-memmove.c \
runtime/go-memequal.c \
runtime/go-mmap.c \
runtime/go-nanotime.c \
runtime/go-now.c \
runtime/go-nosys.c \
@ -1385,6 +1386,8 @@ runtime/go-memmove.lo: runtime/$(am__dirstamp) \
runtime/$(DEPDIR)/$(am__dirstamp)
runtime/go-memequal.lo: runtime/$(am__dirstamp) \
runtime/$(DEPDIR)/$(am__dirstamp)
runtime/go-mmap.lo: runtime/$(am__dirstamp) \
runtime/$(DEPDIR)/$(am__dirstamp)
runtime/go-nanotime.lo: runtime/$(am__dirstamp) \
runtime/$(DEPDIR)/$(am__dirstamp)
runtime/go-now.lo: runtime/$(am__dirstamp) \
@ -1454,6 +1457,7 @@ distclean-compile:
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-memclr.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-memequal.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-memmove.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-mmap.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-nanotime.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-nosys.Plo@am__quote@
@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-now.Plo@am__quote@

6
libgo/go/runtime/mem_gccgo.go
View file

@ -14,8 +14,8 @@ import (
//go:linkname sysAlloc
//go:linkname sysFree
//extern mmap
func sysMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off _libgo_off_t_type) unsafe.Pointer
//extern __go_mmap
func sysMmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uintptr) unsafe.Pointer
//extern munmap
func munmap(addr unsafe.Pointer, length uintptr) int32
@ -38,7 +38,7 @@ func init() {
}
func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uintptr) (unsafe.Pointer, int) {
p := sysMmap(addr, n, prot, flags, fd, _libgo_off_t_type(off))
p := sysMmap(addr, n, prot, flags, fd, off)
if uintptr(p) == _MAP_FAILED {
return nil, errno()
}

21
libgo/runtime/go-mmap.c Normal file
View file

@ -0,0 +1,21 @@
/* go-mmap.c -- functions for calling C mmap functions.
Copyright 2023 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 "config.h"
#include <stdint.h>
#include <sys/mman.h>
/* The exact C function to call varies between mmap and mmap64, and
the size of the off_t argument also varies. Here we provide a
function that Go code can call with consistent types. */
void *
__go_mmap(void *addr, uintptr_t length, int32_t prot, int32_t flags,
int32_t fd, uintptr_t offset)
{
return mmap(addr, length, prot, flags, fd, offset);
}

3
libgo/runtime/runtime.h
View file

@ -355,9 +355,6 @@ bool runtime_notetsleepg(Note*, int64) // false - timeout
/*
* low level C-called
*/
#define runtime_mmap mmap
#define runtime_munmap munmap
#define runtime_madvise madvise
#define runtime_memclr(buf, size) __builtin_memset((buf), 0, (size))
#define runtime_getcallerpc() __builtin_return_address(0)