prepare to hide kernel symbols: expose libc symbols in certain files

This 2nd patch in the series annotates number of standard glibc symbols across number of source files, mostly under bsd, core, fs and libc folders. This does not have any effect until we introduce the changes to the makefile to support compiling kernel with most symbols hidden. We choose to annotate the symbols that need to be exposed because the relevant files will be compiled with the flag '-fvisibility=hidden' which would hide all symbols unless annotated otherwise which takes precedence. This approach helps to minimize the number of symbols that need to be annotated. certain files Comparing to the version 1 of this patch, this one differs in the following ways: - removes changes made to bsd/sys/netinet/in.n, bsd/sys/rpc/xdr.h, bsd/sys/sys/md5.h and bsd/sys/sys/libkern.h to avoid exposing symbols originating from FreeBSD kernel that may not be completely compatible with Linux - moves some of the OSV_*API annotation from header files to the source files Signed-off-by: Waldemar Kozaczuk <jwkozaczuk@gmail.com>
cloudius-systems · Nov 28, 2021 · 317d259 · 317d259
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commit 317d259
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diff --git a/arch/aarch64/feexcept.cc b/arch/aarch64/feexcept.cc
@@ -36,6 +36,7 @@
 #include <sys/types.h>
 #include <fenv.h>
 #include <__fenv.h>
+#include <osv/export.h>
 // Note that musl's fenv.h does not define feenableexcept and friends, so
 // we need to 'extern "C"' them here, as no header file does this.
 
@@ -55,7 +56,7 @@ typedef	__uint64_t	_fenv_t;
 #define	__mrs_fpsr(__r)	__asm __volatile("mrs %0, fpsr" : "=r" (__r))
 #define	__msr_fpsr(__r)	__asm __volatile("msr fpsr, %0" : : "r" (__r))
 
-extern "C"
+extern "C" OSV_LIBM_API
 int feenableexcept(int mask)
 {
     _fenv_t __old_r, __new_r;
@@ -66,7 +67,7 @@ int feenableexcept(int mask)
     return ((__old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT);
 }
 
-extern "C"
+extern "C" OSV_LIBM_API
 int fedisableexcept(int mask)
 {
     _fenv_t __old_r, __new_r;
@@ -77,7 +78,7 @@ int fedisableexcept(int mask)
     return ((__old_r >> _FPUSW_SHIFT) & FE_ALL_EXCEPT);
 }
 
-extern "C"
+extern "C" OSV_LIBM_API
 int fegetexcept()
 {
     _fenv_t __r;

diff --git a/arch/x64/feexcept.cc b/arch/x64/feexcept.cc
@@ -8,7 +8,9 @@
 #include <osv/types.h>
 #include <fenv.h>
 #include <__fenv.h>
+#include <osv/export.h>
 
+OSV_LIBM_API
 int feenableexcept(int mask)
 {
     // The feenableexcept() manual page suggests that -1 should be returned
@@ -38,6 +40,7 @@ int feenableexcept(int mask)
     return ret;
 }
 
+OSV_LIBM_API
 int fedisableexcept(int mask)
 {
     mask &= FE_ALL_EXCEPT;
@@ -56,6 +59,7 @@ int fedisableexcept(int mask)
     return ret;
 }
 
+OSV_LIBM_API
 int fegetexcept()
 {
     u16 cw;

diff --git a/bsd/sys/kern/uipc_syscalls_wrap.cc b/bsd/sys/kern/uipc_syscalls_wrap.cc
@@ -5,13 +5,14 @@
 
 #include <bsd/uipc_syscalls.h>
 #include <osv/debug.h>
+#include <osv/export.h>
 #include "libc/af_local.h"
 
 #include "libc/internal/libc.h"
 
 #define sock_d(...)		tprintf_d("socket-api", __VA_ARGS__);
 
-extern "C"
+extern "C" OSV_LIBC_API
 int socketpair(int domain, int type, int protocol, int sv[2])
 {
 	int error;
@@ -32,7 +33,7 @@ int socketpair(int domain, int type, int protocol, int sv[2])
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int getsockname(int sockfd, struct bsd_sockaddr *addr, socklen_t *addrlen)
 {
 	int error;
@@ -49,7 +50,7 @@ int getsockname(int sockfd, struct bsd_sockaddr *addr, socklen_t *addrlen)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int getpeername(int sockfd, struct bsd_sockaddr *addr, socklen_t *addrlen)
 {
 	int error;
@@ -66,7 +67,7 @@ int getpeername(int sockfd, struct bsd_sockaddr *addr, socklen_t *addrlen)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int accept4(int fd, struct bsd_sockaddr *__restrict addr, socklen_t *__restrict len, int flg)
 {
 	int fd2, error;
@@ -83,7 +84,7 @@ int accept4(int fd, struct bsd_sockaddr *__restrict addr, socklen_t *__restrict
 	return fd2;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int accept(int fd, struct bsd_sockaddr *__restrict addr, socklen_t *__restrict len)
 {
 	int fd2, error;
@@ -100,7 +101,7 @@ int accept(int fd, struct bsd_sockaddr *__restrict addr, socklen_t *__restrict l
 	return fd2;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int bind(int fd, const struct bsd_sockaddr *addr, socklen_t len)
 {
 	int error;
@@ -117,7 +118,7 @@ int bind(int fd, const struct bsd_sockaddr *addr, socklen_t len)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int connect(int fd, const struct bsd_sockaddr *addr, socklen_t len)
 {
 	int error;
@@ -134,7 +135,7 @@ int connect(int fd, const struct bsd_sockaddr *addr, socklen_t len)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int listen(int fd, int backlog)
 {
 	int error;
@@ -151,7 +152,7 @@ int listen(int fd, int backlog)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t recvfrom(int fd, void *__restrict buf, size_t len, int flags,
 		struct bsd_sockaddr *__restrict addr, socklen_t *__restrict alen)
 {
@@ -171,7 +172,7 @@ ssize_t recvfrom(int fd, void *__restrict buf, size_t len, int flags,
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t recv(int fd, void *buf, size_t len, int flags)
 {
 	int error;
@@ -189,7 +190,7 @@ ssize_t recv(int fd, void *buf, size_t len, int flags)
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t recvmsg(int fd, struct msghdr *msg, int flags)
 {
 	ssize_t bytes;
@@ -207,7 +208,7 @@ ssize_t recvmsg(int fd, struct msghdr *msg, int flags)
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t sendto(int fd, const void *buf, size_t len, int flags,
     const struct bsd_sockaddr *addr, socklen_t alen)
 {
@@ -227,7 +228,7 @@ ssize_t sendto(int fd, const void *buf, size_t len, int flags,
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t send(int fd, const void *buf, size_t len, int flags)
 {
 	int error;
@@ -245,7 +246,7 @@ ssize_t send(int fd, const void *buf, size_t len, int flags)
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 ssize_t sendmsg(int fd, const struct msghdr *msg, int flags)
 {
 	ssize_t bytes;
@@ -263,7 +264,7 @@ ssize_t sendmsg(int fd, const struct msghdr *msg, int flags)
 	return bytes;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int getsockopt(int fd, int level, int optname, void *__restrict optval,
 		socklen_t *__restrict optlen)
 {
@@ -281,7 +282,7 @@ int getsockopt(int fd, int level, int optname, void *__restrict optval,
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int setsockopt(int fd, int level, int optname, const void *optval, socklen_t optlen)
 {
 	int error;
@@ -299,7 +300,7 @@ int setsockopt(int fd, int level, int optname, const void *optval, socklen_t opt
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int shutdown(int fd, int how)
 {
 	int error;
@@ -322,7 +323,7 @@ int shutdown(int fd, int how)
 	return 0;
 }
 
-extern "C"
+extern "C" OSV_LIBC_API
 int socket(int domain, int type, int protocol)
 {
 	int s, error;

diff --git a/bsd/sys/xen/xenstore/xenstore.cc b/bsd/sys/xen/xenstore/xenstore.cc
@@ -65,6 +65,7 @@ __FBSDID("$FreeBSD$");
 
 #include <xen/xenstore/xenstorevar.h>
 #include <xen/xenstore/xenstore_internal.h>
+#include <osv/export.h>
 
 #include <vm/vm.h>
 #include <vm/pmap.h>
@@ -1316,6 +1317,7 @@ class xs_sbuf {
 
 /*-------------------------------- Public API --------------------------------*/
 /*------- API comments for these methods can be found in xenstorevar.h -------*/
+OSV_LIBXENSTORE_API
 const char **
 xs_directory(void *op, struct xs_transaction t, const char *path, u_int *num)
 {
@@ -1360,6 +1362,7 @@ xs_exists(struct xs_transaction t, const char *dir, const char *node)
 	return (1);
 }
 
+OSV_LIBXENSTORE_API
 char *
 xs_read(void *op, struct xs_transaction t, const char *path, u_int *len)
 {
@@ -1387,6 +1390,7 @@ xs_read(struct xs_transaction t, const char *dir, const char *node,
 	return 0;
 }
 
+OSV_LIBXENSTORE_API
 int
 xs_write(void *op, struct xs_transaction t, const char *path, const char *string)
 {
@@ -1403,11 +1407,13 @@ xs_write(void *op, struct xs_transaction t, const char *path, const char *string
 	return (error);
 }
 
+OSV_LIBXENSTORE_API
 void *xs_daemon_open()
 {
 	return (void *)-1;
 }
 
+OSV_LIBXENSTORE_API
 void xs_close(void *h)
 {
 }
@@ -1433,7 +1439,7 @@ xs_mkdir(struct xs_transaction t, const char *dir, const char *node)
 	return (ret);
 }
 
-
+OSV_LIBXENSTORE_API
 int
 xs_rm(void *op, struct xs_transaction t, const char *path)
 {
@@ -1562,6 +1568,7 @@ xs_transaction_start(struct xs_transaction *t)
 	return (error);
 }
 
+OSV_LIBXENSTORE_API
 int
 xs_transaction_start(void *h)
 {
@@ -1583,6 +1590,7 @@ xs_transaction_end(struct xs_transaction t, int abort)
 	return (xs_single(t, XS_TRANSACTION_END, abortstr, NULL, NULL));
 }
 
+OSV_LIBXENSTORE_API
 int
 xs_transaction_end(void *h, struct xs_transaction t, int abort)
 {

diff --git a/core/app.cc b/core/app.cc
@@ -11,6 +11,7 @@
 #include <osv/run.hh>
 #include <osv/power.hh>
 #include <osv/trace.hh>
+#include <osv/export.h>
 #include <functional>
 #include <thread>
 #include <libgen.h>
@@ -26,9 +27,11 @@ extern int optind;
 
 // Java uses this global variable (supplied by Glibc) to figure out
 // aproximatively where the initial thread's stack end.
+OSV_LD_LINUX_x86_64_API
 void *__libc_stack_end;
 
-extern "C" void __libc_start_main(int (*main)(int, char**), int, char**,
+extern "C" OSV_LIBC_API
+void __libc_start_main(int (*main)(int, char**), int, char**,
     void(*)(), void(*)(), void(*)(), void*)
 {
     auto app = osv::application::get_current();

diff --git a/core/elf.cc b/core/elf.cc
@@ -26,6 +26,7 @@
 #include <osv/stubbing.hh>
 #include <sys/utsname.h>
 #include <osv/demangle.hh>
+#include <osv/export.h>
 #include <boost/version.hpp>
 #include <deque>
 
@@ -1325,6 +1326,7 @@ program::program(void* addr)
           "libaio.so.1",
           "libxenstore.so.3.0",
           "libcrypt.so.1",
+          "libutil.so",
     };
     auto ml = new modules_list();
     ml->objects.push_back(_core.get());
@@ -1876,7 +1878,7 @@ char *object::setup_tls()
             _module_index, _tls_segment, _tls_init_size, _tls_uninit_size);
 }
 
-extern "C"
+extern "C" OSV_LD_LINUX_x86_64_API
 void* __tls_get_addr(module_and_offset* mao)
 {
 #ifdef AARCH64_PORT_STUB
@@ -1901,7 +1903,7 @@ void* __tls_get_addr(module_and_offset* mao)
 // also uses a static area for uname, we can just return that.
 extern utsname utsname;
 
-extern "C"
+extern "C" OSV_LIBC_API
 unsigned long getauxval(unsigned long type)
 {
     switch (type) {