| Message ID | 20231124135903.16621-1-jgross@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [RFC] Mini-OS: explicitly mark symbols to be visible for apps | expand |
Juergen Gross, le ven. 24 nov. 2023 14:59:03 +0100, a ecrit: > Add an EXPORT_SYMBOL() macro to explicitly mark a symbol to be visible > for an app or library linked with Mini-OS. This enables to hide all > other symbols from external components, avoiding any problems with > duplicate symbol names. > > Signed-off-by: Juergen Gross <jgross@suse.com> Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org> > --- > Based on top of my previous series "Mini-OS: hide mini-os internal > symbols". > This is a RFC as an alternative to the map file containing all > visible symbol names. It would add more code churn, but it has the > large benefit of declaring visibility of a symbol at the place > where it is defined, reducing the chance to miss a proper symbol > visibility definition. > This patch is including an example for the do_exit() function in > order to prove the viability of the approach. > In case this idea is approved, I'd setup a patch series replacing > the second patch of above series with this patch (minus the do_exit() > example) and the scattered EXPORT_SYMBOL() instances. I agree on the rationale, indeed. > Signed-off-by: Juergen Gross <jgross@suse.com> > --- > Makefile | 3 ++- > include/lib.h | 6 ++++++ > kernel.c | 1 + > mini-os.map | 1 - > 4 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index d4768110..5dbad8ce 100644 > --- a/Makefile > +++ b/Makefile > @@ -166,7 +166,8 @@ $(OBJ_DIR)/arch/x86/minios-x86%.lds: arch/x86/minios-x86.lds.S > > $(OBJ_DIR)/$(TARGET)-kern.o: $(OBJS) arch_lib $(OBJ_DIR)/$(TARGET_ARCH_DIR)/minios-$(MINIOS_TARGET_ARCH).lds mini-os.map > $(LD) -r $(LDFLAGS) $(HEAD_OBJ) $(OBJS) $(LDARCHLIB) -o $@ > - $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map $@ $@ > + $(OBJCOPY) --dump-section .export_symbol=syms mini-os-kern.o > + $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map --keep-global-symbols=syms --remove-section=.export_symbol $@ $@ > > $(OBJ_DIR)/$(TARGET): $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) > $(LD) -r $(LDFLAGS) $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LDLIBS) -o $@.o > diff --git a/include/lib.h b/include/lib.h > index dd68985a..24fd0186 100644 > --- a/include/lib.h > +++ b/include/lib.h > @@ -64,6 +64,12 @@ > #define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond)) > #endif > > +#define EXPORT_SYMBOL(sym) \ > + extern typeof(sym) sym; \ > + asm(".section \".export_symbol\",\"a\"\n" \ > + "\t.ascii \""#sym"\n\"\n" \ > + ".previous") > + > #ifdef HAVE_LIBC > #include <sys/queue.h> > #include <sys/stat.h> > diff --git a/kernel.c b/kernel.c > index 1f97d8dd..29eed535 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -199,3 +199,4 @@ void do_exit(void) > HYPERVISOR_sched_op(SCHEDOP_shutdown, &sched_shutdown); > } > } > +EXPORT_SYMBOL(do_exit); > diff --git a/mini-os.map b/mini-os.map > index 58a3a0ee..90f02edf 100644 > --- a/mini-os.map > +++ b/mini-os.map > @@ -69,7 +69,6 @@ close > closedir > closelog > connect > -do_exit > dup > dup2 > err > -- > 2.35.3 >
diff --git a/Makefile b/Makefile index d4768110..5dbad8ce 100644 --- a/Makefile +++ b/Makefile @@ -166,7 +166,8 @@ $(OBJ_DIR)/arch/x86/minios-x86%.lds: arch/x86/minios-x86.lds.S $(OBJ_DIR)/$(TARGET)-kern.o: $(OBJS) arch_lib $(OBJ_DIR)/$(TARGET_ARCH_DIR)/minios-$(MINIOS_TARGET_ARCH).lds mini-os.map $(LD) -r $(LDFLAGS) $(HEAD_OBJ) $(OBJS) $(LDARCHLIB) -o $@ - $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map $@ $@ + $(OBJCOPY) --dump-section .export_symbol=syms mini-os-kern.o + $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* --keep-global-symbols=mini-os.map --keep-global-symbols=syms --remove-section=.export_symbol $@ $@ $(OBJ_DIR)/$(TARGET): $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LD) -r $(LDFLAGS) $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LDLIBS) -o $@.o diff --git a/include/lib.h b/include/lib.h index dd68985a..24fd0186 100644 --- a/include/lib.h +++ b/include/lib.h @@ -64,6 +64,12 @@ #define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond)) #endif +#define EXPORT_SYMBOL(sym) \ + extern typeof(sym) sym; \ + asm(".section \".export_symbol\",\"a\"\n" \ + "\t.ascii \""#sym"\n\"\n" \ + ".previous") + #ifdef HAVE_LIBC #include <sys/queue.h> #include <sys/stat.h> diff --git a/kernel.c b/kernel.c index 1f97d8dd..29eed535 100644 --- a/kernel.c +++ b/kernel.c @@ -199,3 +199,4 @@ void do_exit(void) HYPERVISOR_sched_op(SCHEDOP_shutdown, &sched_shutdown); } } +EXPORT_SYMBOL(do_exit); diff --git a/mini-os.map b/mini-os.map index 58a3a0ee..90f02edf 100644 --- a/mini-os.map +++ b/mini-os.map @@ -69,7 +69,6 @@ close closedir closelog connect -do_exit dup dup2 err