[Apple Silicon] Initial support for Rosetta

[davide]

Summary

Translated processes talk with a different debugserver, shipped with macOS 11.
This patch detects whether a process is translated and attaches to the correct debugserver implementation. It's the first patch of a series. Tested on the lldb test suite.

[jasonmolenda]

LGTM. With p_flag, we only need to evaluate (processInfo.kp_proc.p_flag & P_TRANSLATED) as a boolean, but that's a style pref as much as anything.

[davide]

In D82491#2112269, @jasonmolenda wrote:

LGTM. With p_flag, we only need to evaluate (processInfo.kp_proc.p_flag & P_TRANSLATED) as a boolean, but that's a style pref as much as anything.

Fair, let me change that.

[davide]

commit fd19ddb8f2a2b082f492fc59f7f360adf3495701 (HEAD -> master, origin/master, origin/HEAD)
Author: Davide Italiano <[e-mail]>
Date:   Wed Jun 24 12:18:29 2020 -0700

    [Apple Silicon] Initial support for Rosetta
    
    Translated processes talk with a different debugserver, shipped with
    macOS 11. This patch detects whether a process is translated and
    attaches to the correct debugserver implementation.
    It's the first patch of a series. Tested on the lldb test suite.
    
    Differential Revision:  https://reviews.llvm.org/D82491

[JDevlieghere]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

3444

The sysctl call seems like something that would fit into host, we already have a bunch of those in Host.mm. Should we create a function there that returns whether a given pid runs under Rosetta?

[echristo]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

20

This is problematic in that sys/sysctl is deprecated on linux (causing warnings/Werror failures).

[echristo]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

20

I'm going to #ifdef this only in for apple at the moment matching the use below.

3444

Agreed. That seems much cleaner.

[echristo]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

20

I see you've done that already :)

[davide]

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

3444

https://reviews.llvm.org/D82813

lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

 #include <stdlib.h>
 #if LLDB_ENABLE_POSIX
 #include <netinet/in.h>
 #include <sys/mman.h>
 #include <sys/socket.h>
 #include <unistd.h>
 #endif
 #include <sys/stat.h>
+#include <sys/sysctl.h>
 #include <sys/types.h>
 #include <time.h>
 
 #include <algorithm>
 #include <csignal>
 #include <map>
 #include <memory>
 #include <mutex>

     debugserver_launch_info.SetLaunchInSeparateProcessGroup(true);
 
     const std::weak_ptr<ProcessGDBRemote> this_wp =
         std::static_pointer_cast<ProcessGDBRemote>(shared_from_this());
     debugserver_launch_info.SetMonitorProcessCallback(
         std::bind(MonitorDebugserverProcess, this_wp, _1, _2, _3, _4), false);
     debugserver_launch_info.SetUserID(process_info.GetUserID());
 
+#if defined(__APPLE__)
+    // On macOS 11, we need to support x86_64 applications translated to
+    // arm64. We check whether a binary is translated and spawn the correct
+    // debugserver accordingly.
+    int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_PID,
+                  static_cast<int>(process_info.GetProcessID()) };
+    struct kinfo_proc processInfo;
+    size_t bufsize = sizeof(processInfo);
+    if (sysctl(mib, (unsigned)(sizeof(mib)/sizeof(int)), &processInfo,
+               &bufsize, NULL, 0) == 0 && bufsize > 0) {
+      if ((processInfo.kp_proc.p_flag & P_TRANSLATED) == P_TRANSLATED) {
+        FileSpec rosetta_debugserver("/Library/Apple/usr/libexec/oah/debugserver");
+        debugserver_launch_info.SetExecutableFile(rosetta_debugserver, false);
+      }
+    }
+#endif
+
     int communication_fd = -1;
 #ifdef USE_SOCKETPAIR_FOR_LOCAL_CONNECTION
     // Use a socketpair on non-Windows systems for security and performance
     // reasons.
     int sockets[2]; /* the pair of socket descriptors */
     if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) == -1) {
       error.SetErrorToErrno();
       return error;