runtime: fixes for -buildmode=c-archive

    
    With -buildmode=c-archive, initsig is called before the memory
    allocator has been initialized.  The code was doing a memory
    allocation because of the call to funcPC(sigtramp).  When escape
    analysis is fully implemented, that call should not allocate.  For
    now, finesse the issue by calling a C function to get the C function
    pointer value of sigtramp.
    
    When returning from a call from C to a Go function, a deferred
    function is run to go back to syscall mode.  When the call occurs on a
    non-Go thread, that call sets g to nil, making it impossible to add
    the _defer struct back to the pool.  Just drop it and let the garbage
    collector clean it up.
    
    Reviewed-on: https://go-review.googlesource.com/33675

From-SVN: r242992

1 files changed, 9 insertions, 0 deletions

diff --git a/libgo/runtime/go-signal.c b/libgo/runtime/go-signal.c
index c1f1a52..711f71e 100644
--- a/libgo/runtime/go-signal.c
+++ b/libgo/runtime/go-signal.c
@@ -140,6 +140,15 @@ sigtramp(int sig, siginfo_t *info, void *context)
 
 #endif // USING_SPLIT_STACK
 
+// C function to return the address of the sigtramp function.
+uintptr getSigtramp(void) __asm__ (GOSYM_PREFIX "runtime.getSigtramp");
+
+uintptr
+getSigtramp()
+{
+  return (uintptr)(void*)sigtramp;
+}
+
 // C code to manage the sigaction sa_sigaction field, which is
 // typically a union and so hard for mksysinfo.sh to handle.