fix clobber of edx in i386 vsyscall asm

this function does not obey the normal calling convention; like a
syscall instruction, it's expected not to clobber any registers except
the return value. clobbering edx could break callers that were reusing
the value cached in edx after the syscall returns.

diff --git a/src/internal/i386/syscall.s b/src/internal/i386/syscall.s
index 291168c..2914ace 100644 (file)
--- a/src/internal/i386/syscall.s
+++ b/src/internal/i386/syscall.s
@@ -16,7 +16,8 @@ __vsyscall:
        mov 12(%esp),%edi
        push %eax
        call 1f
-2:     pop %ebx
+2:     mov %ebx,%edx
+       pop %ebx
        pop %ebx
        pop %edi
        ret