syscall: remove ptrace1 on darwin

On Darwin, the ptrace syscall is called in ptrace1, which then be
called in ptrace. This allows ptrace1 be disabled on iOS (by
implementing ptrace differently). But we can also achieve this by
adding a conditional directly in ptrace. This reduces stack usage
with -N -l, while keeping ptrace disabled on iOS.

For #64113.

Change-Id: I89d8e317e77352fffdbb5a25ba21ee9cdf2e1e20
Reviewed-on: https://go-review.googlesource.com/c/go/+/545276
Reviewed-by: Michael Knyszek <[email protected]>
Run-TryBot: Cherry Mui <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: cherrymui

src/syscall/mksyscall.pl

@@ -85,6 +85,9 @@
 if($libc) {
 	$extraimports = 'import "internal/abi"';
 }
+if($darwin) {
+	$extraimports .= "\nimport \"runtime\"";
+}
 
 sub parseparamlist($) {
 	my ($list) = @_;
@@ -137,7 +140,7 @@ ($)
 	# without reading the header.
 	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
 
-	if (($darwin && $func =~ /^ptrace1(Ptr)?$/) || (($openbsd && $libc) && $func =~ /^ptrace(Ptr)?$/)) {
+	if ((($darwin || ($openbsd && $libc)) && $func =~ /^ptrace(Ptr)?$/)) {
 		# The ptrace function is called from forkAndExecInChild where stack
 		# growth is forbidden.
 		$text .= "//go:nosplit\n"
@@ -147,6 +150,13 @@ ($)
 	my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : "";
 	$text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl;
 
+	# Disable ptrace on iOS.
+	if ($darwin && $func =~ /^ptrace(Ptr)?$/) {
+		$text .= "\tif runtime.GOOS == \"ios\" {\n";
+		$text .= "\t\tpanic(\"unimplemented\")\n";
+		$text .= "\t}\n";
+	}
+
 	# Check if err return available
 	my $errvar = "";
 	foreach my $p (@out) {

src/syscall/ptrace_darwin.go

@@ -24,7 +24,7 @@ func setTimeval(sec, usec int64) Timeval {
 //sys	Stat(path string, stat *Stat_t) (err error) = SYS_stat64
 //sys	Statfs(path string, stat *Statfs_t) (err error) = SYS_statfs64
 //sys   fstatat(fd int, path string, stat *Stat_t, flags int) (err error) = SYS_fstatat64
-//sys   ptrace1(request int, pid int, addr uintptr, data uintptr) (err error) = SYS_ptrace
+//sys   ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
 
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)

src/syscall/ptrace_ios.go

@@ -24,7 +24,7 @@ func setTimeval(sec, usec int64) Timeval {
 //sys	Stat(path string, stat *Stat_t) (err error)
 //sys	Statfs(path string, stat *Statfs_t) (err error)
 //sys	fstatat(fd int, path string, stat *Stat_t, flags int) (err error)
-//sys	ptrace1(request int, pid int, addr uintptr, data uintptr) (err error) = SYS_ptrace
+//sys	ptrace(request int, pid int, addr uintptr, data uintptr) (err error)
 
 func SetKevent(k *Kevent_t, fd, mode, flags int) {
 	k.Ident = uint64(fd)