cmd/nm: don't add filename elements for m symbols

The compilers used to generate only one 'm' symbol
to record the stack frame size for each function.

In cmd/nm, the 'm' and 'f' symbols are handled in
the same switch case with a special exception for
the symbol described above called ".frame".

Now that the compilers emit additional 'm' symbols
for precise garbage collection of the stack, the
current logic is incorrect. cmd/nm will attempt to
interpret these new 'm' symbols as 'f' symbols and
add them to the file name index table.

This fails with an out-of-memory condition when
zenter encounters an 'm' symbol with a very large
value (usually the .args symbol indicating a
variadic NOSPLIT function).

R=iant
CC=dave, gobot, golang-dev, rsc
https://golang.org/cl/7962045

diff --git a/src/cmd/nm/nm.c b/src/cmd/nm/nm.c
index 6682390358b6f554a392d6ee61e437e33a782e36..aa056b88253bf4948cc9c60d2e0479fba335257e 100644 (file)
--- a/src/cmd/nm/nm.c
+++ b/src/cmd/nm/nm.c
@@ -275,11 +275,13 @@ psym(Sym *s, void* p)
                        return;
                break;
        case 'm':
+               if(!aflag || uflag || gflag)
+                       return;
+               break;
        case 'f':       /* we only see a 'z' when the following is true*/
                if(!aflag || uflag || gflag)
                        return;
-               if (strcmp(s->name, ".frame"))
-                       zenter(s);
+               zenter(s);
                break;
        case 'a':
        case 'p':