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unix: convert openbsd/arm64 to direct libc calls

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The current code has continued to work on OpenBSD, since it has been using
syscall(2) via libc. However, the system call numbers are still hardcoded in
golang.org/sys/unix. Various system call changes have been made in OpenBSD,
resulting in changes to the system call numbers and arguments, which now
fail when this package is used.

Switch to calling various system calls directly via libc, rather than calling
via libc using syscall(2).

Updates golang/go#36435

Change-Id: I836a484b14e0a427ac565315e27f0de1e9a5d021
Reviewed-on: https://go-review.googlesource.com/c/sys/+/421796
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Joel Sing
2022-08-11 17:12:43 +00:00
committed by Gopher Robot
parent 1c4a2a72c6
commit 74508daebc
6 changed files with 1501 additions and 143 deletions
Download Patch File Download Diff File Expand all files Collapse all files
unix/mksyscall.go
+18 -6
View File
@@ -36,6 +36,7 @@ import (
var (
b32 = flag.Bool("b32", false, "32bit big-endian")
l32 = flag.Bool("l32", false, "32bit little-endian")
libc = flag.Bool("libc", false, "libc system calls")
plan9 = flag.Bool("plan9", false, "plan9")
openbsd = flag.Bool("openbsd", false, "openbsd")
netbsd = flag.Bool("netbsd", false, "netbsd")
@@ -43,6 +44,8 @@ var (
arm = flag.Bool("arm", false, "arm") // 64-bit value should use (even, odd)-pair
tags = flag.String("tags", "", "build tags")
filename = flag.String("output", "", "output file name (standard output if omitted)")
libcPath = "libc.so"
)
// cmdLine returns this programs's commandline arguments
@@ -124,10 +127,11 @@ func main() {
endianness = "little-endian"
}
libc := false
if goos == "darwin" {
libc = true
libcPath = "/usr/lib/libSystem.B.dylib"
*libc = true
}
trampolines := map[string]bool{}
text := ""
@@ -210,7 +214,7 @@ func main() {
text += fmt.Sprintf(" else {\n\t\t_p%d = unsafe.Pointer(&_zero)\n\t}\n", n)
args = append(args, fmt.Sprintf("uintptr(_p%d)", n), fmt.Sprintf("uintptr(len(%s))", p.Name))
n++
} else if p.Type == "int64" && (*openbsd || *netbsd) {
} else if p.Type == "int64" && ((*openbsd && !*libc) || *netbsd) {
args = append(args, "0")
if endianness == "big-endian" {
args = append(args, fmt.Sprintf("uintptr(%s>>32)", p.Name), fmt.Sprintf("uintptr(%s)", p.Name))
@@ -285,10 +289,18 @@ func main() {
}
var libcFn string
if libc {
if *libc {
asm = "syscall_" + strings.ToLower(asm[:1]) + asm[1:] // internal syscall call
sysname = strings.TrimPrefix(sysname, "SYS_") // remove SYS_
sysname = strings.ToLower(sysname) // lowercase
if *openbsd && *libc {
switch sysname {
case "__getcwd":
sysname = "getcwd"
case "__sysctl":
sysname = "sysctl"
}
}
libcFn = sysname
sysname = "libc_" + sysname + "_trampoline_addr"
}
@@ -360,14 +372,14 @@ func main() {
text += "\treturn\n"
text += "}\n\n"
if libc && !trampolines[libcFn] {
if *libc && !trampolines[libcFn] {
// some system calls share a trampoline, like read and readlen.
trampolines[libcFn] = true
// Declare assembly trampoline address.
text += fmt.Sprintf("var libc_%s_trampoline_addr uintptr\n\n", libcFn)
// Assembly trampoline calls the libc_* function, which this magic
// redirects to use the function from libSystem.
text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s \"/usr/lib/libSystem.B.dylib\"\n", libcFn, libcFn)
text += fmt.Sprintf("//go:cgo_import_dynamic libc_%s %s %q\n", libcFn, libcFn, libcPath)
text += "\n"
}
}