diff options
| -rw-r--r-- | Makefile | 2 | ||||
| -rwxr-xr-x | configure | 31 | ||||
| -rw-r--r-- | src/internal/vis.h | 40 |
3 files changed, 72 insertions, 1 deletions
diff --git a/Makefile b/Makefile index d943988d..15a30f83 100644 --- a/Makefile +++ b/Makefile @@ -104,6 +104,8 @@ NOSSP_SRCS = $(wildcard crt/*.c) \ src/ldso/dlstart.c src/ldso/dynlink.c $(NOSSP_SRCS:%.c=%.o) $(NOSSP_SRCS:%.c=%.lo): CFLAGS += $(CFLAGS_NOSSP) +$(CRT_LIBS): CFLAGS += -DCRT + # This incantation ensures that changes to any subarch asm files will # force the corresponding object file to be rebuilt, even if the implicit # rule below goes indirectly through a .sub file. diff --git a/configure b/configure index 41a73b46..0e396941 100755 --- a/configure +++ b/configure @@ -27,6 +27,7 @@ Optional features: --enable-optimize=... optimize listed components for speed over size [auto] --enable-debug build with debugging information [disabled] --enable-warnings build with recommended warnings flags [disabled] + --enable-visibility use global visibility options to optimize PIC [auto] --enable-gcc-wrapper build musl-gcc toolchain wrapper [auto] --disable-shared inhibit building shared library [enabled] --disable-static inhibit building static library [enabled] @@ -79,7 +80,7 @@ fi tryflag () { printf "checking whether compiler accepts %s... " "$2" echo "typedef int x;" > "$tmpc" -if $CC "$2" -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then +if $CC $2 -c -o /dev/null "$tmpc" >/dev/null 2>&1 ; then printf "yes\n" eval "$1=\"\${$1} \$2\"" eval "$1=\${$1# }" @@ -124,6 +125,7 @@ target= optimize=auto debug=no warnings=no +visibility=auto shared=auto static=yes wrapper=auto @@ -148,6 +150,8 @@ case "$arg" in --disable-debug|--enable-debug=no) debug=no ;; --enable-warnings|--enable-warnings=yes) warnings=yes ;; --disable-warnings|--enable-warnings=no) warnings=no ;; +--enable-visibility|--enable-visibility=yes) visibility=yes ;; +--disable-visibility|--enable-visibility=no) visibility=no ;; --enable-gcc-wrapper|--enable-gcc-wrapper=yes) wrapper=yes ;; --disable-gcc-wrapper|--enable-gcc-wrapper=no) wrapper=no ;; --enable-*|--disable-*|--with-*|--without-*|--*dir=*|--build=*) ;; @@ -415,6 +419,31 @@ tryflag CFLAGS_AUTO -Wno-unknown-pragmas tryflag CFLAGS_AUTO -Wno-pointer-to-int-cast fi +if test "x$visibility" == xauto ; then +# This test checks toolchain support for several things: +# - the -include option +# - the attributes/pragmas used in vis.h +# - linking code that takes the address of protected symbols +printf "checking whether global visibility preinclude works... " +echo 'int (*fp)(void);' > "$tmpc" +echo 'int foo(void) { }' >> "$tmpc" +echo 'int bar(void) { fp = foo; return foo(); }' >> "$tmpc" +if $CC $CFLAGS_C99FSE -I./arch/$ARCH -I src/internal -I./include \ + $CPPFLAGS $CFLAGS -DSHARED -fPIC -include vis.h \ + -nostdlib -shared -Wl,-Bsymbolic-functions \ + -o /dev/null "$tmpc" >/dev/null 2>&1 ; then +visibility=yes +else +visibility=no +fi +printf "%s\n" "$visibility" +fi + +if test "x$visibility" == xyes ; then +CFLAGS_AUTO="$CFLAGS_AUTO -include vis.h" +CFLAGS_AUTO="${CFLAGS_AUTO# }" +fi + # Some patched GCC builds have these defaults messed up... tryldflag LDFLAGS_AUTO -Wl,--hash-style=both diff --git a/src/internal/vis.h b/src/internal/vis.h new file mode 100644 index 00000000..bf7a5b20 --- /dev/null +++ b/src/internal/vis.h @@ -0,0 +1,40 @@ +/* This file is only used if enabled in the build system, in which case it is + * included automatically via command line options. It is not included + * explicitly by any source files or other headers. Its purpose is to + * override default visibilities to reduce the size and performance costs + * of position-independent code. */ + +#ifndef CRT +#ifdef SHARED + +/* For shared libc.so, all symbols should be protected, but some toolchains + * fail to support copy relocations for protected data, so exclude all + * exported data symbols. */ + +__attribute__((__visibility__("default"))) +extern struct _IO_FILE *const stdin, *const stdout, *const stderr; + +__attribute__((__visibility__("default"))) +extern int optind, opterr, optopt, optreset, __optreset, getdate_err, h_errno, daylight, __daylight, signgam, __signgam; + +__attribute__((__visibility__("default"))) +extern long timezone, __timezone; + +__attribute__((__visibility__("default"))) +extern char *optarg, **environ, **__environ, *tzname[2], *__tzname[2], *__progname, *__progname_full; + +#pragma GCC visibility push(protected) + +#elif defined(__PIC__) + +/* If building static libc.a as position-independent code, try to make + * everything hidden except possibly-undefined weak references. */ + +__attribute__((__visibility__("default"))) +extern void (*const __init_array_start)(), (*const __init_array_end)(), + (*const __fini_array_start)(), (*const __fini_array_end)(); + +#pragma GCC visibility push(hidden) + +#endif +#endif |