code review 6569068: pkg/runtime: Plan 9: add support for recover() and pani...

src/cmd/dist/buildruntime.c

 // Copyright 2012 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 "a.h"
 
 /*
  * Helpers for building pkg/runtime.
  */
 
@@ skipping 87 matching lines @@
         char *goarch;
         char *goos;
         char *hdr;
 } zasmhdr[] = {
         {"386", "windows",
                 "#define        get_tls(r)      MOVL 0x14(FS), r\n"
                 "#define        g(r)    0(r)\n"
                 "#define        m(r)    4(r)\n"
         },
         {"386", "plan9",
+                "// Plan 9 does not have per-process segment descriptors with\n"
+                "// which to do thread-local storage. Instead, we will use a\n"
+                "// fixed offset from the per-process TOS struct address for\n"
+                "// the local storage. Since the process ID is contained in the\n"
+                "// TOS struct, we specify an offset for that here as well.\n"
                 "#define        get_tls(r)      MOVL _tos(SB), r \n"
                 "#define        g(r)    -8(r)\n"
                 "#define        m(r)    -4(r)\n"
+                "#define        procid(r)       48(r)\n"
         },
         {"386", "linux",
                 "// On Linux systems, what we call 0(GS) and 4(GS) for g and m\n"
                 "// turn into %gs:-8 and %gs:-4 (using gcc syntax to denote\n"
                 "// what the machine sees as opposed to 8l input).\n"
                 "// 8l rewrites 0(GS) and 4(GS) into these.\n"
                 "//\n"
                 "// On Linux Xen, it is not allowed to use %gs:-8 and %gs:-4\n"
                 "// directly.  Instead, we have to store %gs:0 into a temporary\n"
                 "// register and then use -8(%reg) and -4(%reg).  This kind\n"
@@ skipping 236 matching lines @@
         writefile(&out, file, 0);
 
         bfree(&in);
         bfree(&b);
         bfree(&out);
         vfree(&argv);
         vfree(&lines);
         vfree(&fields);
         vfree(&seen);
 }