[PATCH 1/4] um: hostfs: define our own API boundary

* [PATCH 1/4] um: hostfs: define our own API boundary
@ 2023-02-10 21:05 Johannes Berg
  2023-02-10 21:05 ` [PATCH 2/4] um: don't export printf() Johannes Berg
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: Johannes Berg @ 2023-02-10 21:05 UTC (permalink / raw)
  To: linux-um; +Cc: Johannes Berg

From: Johannes Berg <johannes.berg@intel.com>

Instead of exporting the set of functions provided by
glibc that are needed for hostfs_user.c, just build that
into the kernel image whenever hostfs is built, and then
export _those_ functions cleanly, to be independent of
the libc implementation.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 arch/um/os-Linux/user_syms.c | 70 ------------------------------------
 fs/Makefile                  |  2 +-
 fs/hostfs/Makefile           |  6 ++--
 fs/hostfs/hostfs_user_exp.c  | 28 +++++++++++++++
 4 files changed, 33 insertions(+), 73 deletions(-)
 create mode 100644 fs/hostfs/hostfs_user_exp.c

diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c
index fd575ecbcaec..22ed13a9b3e7 100644
--- a/arch/um/os-Linux/user_syms.c
+++ b/arch/um/os-Linux/user_syms.c
@@ -34,81 +34,11 @@ EXPORT_SYMBOL(memset);
 
 EXPORT_SYMBOL(printf);
 
-/* Here, instead, I can provide a fake prototype. Yes, someone cares: genksyms.
- * However, the modules will use the CRC defined *here*, no matter if it is
- * good; so the versions of these symbols will always match
- */
-#define EXPORT_SYMBOL_PROTO(sym)       \
-	int sym(void);                  \
-	EXPORT_SYMBOL(sym);
-
-extern void readdir64(void) __attribute__((weak));
-EXPORT_SYMBOL(readdir64);
-extern void truncate64(void) __attribute__((weak));
-EXPORT_SYMBOL(truncate64);
-
 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 EXPORT_SYMBOL(vsyscall_ehdr);
 EXPORT_SYMBOL(vsyscall_end);
 #endif
 
-EXPORT_SYMBOL_PROTO(__errno_location);
-
-EXPORT_SYMBOL_PROTO(access);
-EXPORT_SYMBOL_PROTO(open);
-EXPORT_SYMBOL_PROTO(open64);
-EXPORT_SYMBOL_PROTO(close);
-EXPORT_SYMBOL_PROTO(read);
-EXPORT_SYMBOL_PROTO(write);
-EXPORT_SYMBOL_PROTO(dup2);
-EXPORT_SYMBOL_PROTO(__xstat);
-EXPORT_SYMBOL_PROTO(__lxstat);
-EXPORT_SYMBOL_PROTO(__lxstat64);
-EXPORT_SYMBOL_PROTO(__fxstat64);
-EXPORT_SYMBOL_PROTO(lseek);
-EXPORT_SYMBOL_PROTO(lseek64);
-EXPORT_SYMBOL_PROTO(chown);
-EXPORT_SYMBOL_PROTO(fchown);
-EXPORT_SYMBOL_PROTO(truncate);
-EXPORT_SYMBOL_PROTO(ftruncate64);
-EXPORT_SYMBOL_PROTO(utime);
-EXPORT_SYMBOL_PROTO(utimes);
-EXPORT_SYMBOL_PROTO(futimes);
-EXPORT_SYMBOL_PROTO(chmod);
-EXPORT_SYMBOL_PROTO(fchmod);
-EXPORT_SYMBOL_PROTO(rename);
-EXPORT_SYMBOL_PROTO(__xmknod);
-
-EXPORT_SYMBOL_PROTO(symlink);
-EXPORT_SYMBOL_PROTO(link);
-EXPORT_SYMBOL_PROTO(unlink);
-EXPORT_SYMBOL_PROTO(readlink);
-
-EXPORT_SYMBOL_PROTO(mkdir);
-EXPORT_SYMBOL_PROTO(rmdir);
-EXPORT_SYMBOL_PROTO(opendir);
-EXPORT_SYMBOL_PROTO(readdir);
-EXPORT_SYMBOL_PROTO(closedir);
-EXPORT_SYMBOL_PROTO(seekdir);
-EXPORT_SYMBOL_PROTO(telldir);
-
-EXPORT_SYMBOL_PROTO(ioctl);
-
-EXPORT_SYMBOL_PROTO(pread64);
-EXPORT_SYMBOL_PROTO(pwrite64);
-
-EXPORT_SYMBOL_PROTO(statfs);
-EXPORT_SYMBOL_PROTO(statfs64);
-
-EXPORT_SYMBOL_PROTO(getuid);
-
-EXPORT_SYMBOL_PROTO(fsync);
-EXPORT_SYMBOL_PROTO(fdatasync);
-
-EXPORT_SYMBOL_PROTO(lstat64);
-EXPORT_SYMBOL_PROTO(fstat64);
-EXPORT_SYMBOL_PROTO(mknod);
-
 /* Export symbols used by GCC for the stack protector. */
 extern void __stack_smash_handler(void *) __attribute__((weak));
 EXPORT_SYMBOL(__stack_smash_handler);
diff --git a/fs/Makefile b/fs/Makefile
index 4dea17840761..59d2e7ecfc36 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -123,7 +123,7 @@ obj-$(CONFIG_9P_FS)		+= 9p/
 obj-$(CONFIG_AFS_FS)		+= afs/
 obj-$(CONFIG_NILFS2_FS)		+= nilfs2/
 obj-$(CONFIG_BEFS_FS)		+= befs/
-obj-$(CONFIG_HOSTFS)		+= hostfs/
+obj-y				+= hostfs/
 obj-$(CONFIG_CACHEFILES)	+= cachefiles/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
 obj-$(CONFIG_TRACING)		+= tracefs/
diff --git a/fs/hostfs/Makefile b/fs/hostfs/Makefile
index d5beaffad43b..1c573eb6193f 100644
--- a/fs/hostfs/Makefile
+++ b/fs/hostfs/Makefile
@@ -3,9 +3,11 @@
 # Licensed under the GPL
 #
 
-hostfs-objs := hostfs_kern.o hostfs_user.o
+hostfs-objs := hostfs_kern.o
 
-obj-y :=
+hostfs-builtin-$(CONFIG_HOSTFS) += hostfs_user.o hostfs_user_exp.o
+
+obj-y := $(hostfs-builtin-y) $(hostfs-builtin-m)
 obj-$(CONFIG_HOSTFS) += hostfs.o
 
 include arch/um/scripts/Makefile.rules
diff --git a/fs/hostfs/hostfs_user_exp.c b/fs/hostfs/hostfs_user_exp.c
new file mode 100644
index 000000000000..250c91c55c46
--- /dev/null
+++ b/fs/hostfs/hostfs_user_exp.c
@@ -0,0 +1,28 @@
+#include <linux/module.h>
+#include "hostfs.h"
+
+EXPORT_SYMBOL_GPL(stat_file);
+EXPORT_SYMBOL_GPL(access_file);
+EXPORT_SYMBOL_GPL(open_file);
+EXPORT_SYMBOL_GPL(open_dir);
+EXPORT_SYMBOL_GPL(seek_dir);
+EXPORT_SYMBOL_GPL(read_dir);
+EXPORT_SYMBOL_GPL(read_file);
+EXPORT_SYMBOL_GPL(write_file);
+EXPORT_SYMBOL_GPL(lseek_file);
+EXPORT_SYMBOL_GPL(fsync_file);
+EXPORT_SYMBOL_GPL(replace_file);
+EXPORT_SYMBOL_GPL(close_file);
+EXPORT_SYMBOL_GPL(close_dir);
+EXPORT_SYMBOL_GPL(file_create);
+EXPORT_SYMBOL_GPL(set_attr);
+EXPORT_SYMBOL_GPL(make_symlink);
+EXPORT_SYMBOL_GPL(unlink_file);
+EXPORT_SYMBOL_GPL(do_mkdir);
+EXPORT_SYMBOL_GPL(hostfs_do_rmdir);
+EXPORT_SYMBOL_GPL(do_mknod);
+EXPORT_SYMBOL_GPL(link_file);
+EXPORT_SYMBOL_GPL(hostfs_do_readlink);
+EXPORT_SYMBOL_GPL(rename_file);
+EXPORT_SYMBOL_GPL(rename2_file);
+EXPORT_SYMBOL_GPL(do_statfs);
-- 
2.39.1


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