Re: [PATCH v3 02/32] Mini-OS: explicitly mark symbols to be visible for apps

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Juergen Gross, le lun. 27 nov. 2023 11:24:53 +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 prepares hiding all
> other symbols from external components, avoiding any problems with
> duplicate symbol names.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> ---
> V3:
> - new patch
> ---
>  .gitignore       |  1 +
>  Makefile         |  3 ++-
>  include/export.h | 10 ++++++++++
>  include/lib.h    |  1 +
>  4 files changed, 14 insertions(+), 1 deletion(-)
>  create mode 100644 include/export.h
> 
> diff --git a/.gitignore b/.gitignore
> index abef46b2..bacf787e 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -16,3 +16,4 @@ mini-os.gz
>  minios-config.mk
>  mini-os-debug
>  mini-os-debug.gz
> +syms
> diff --git a/Makefile b/Makefile
> index 85c6db75..588496cb 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -166,10 +166,11 @@ $(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
>       $(LD) -r $(LDFLAGS) $(HEAD_OBJ) $(OBJS) $(LDARCHLIB) -o $@
> +     $(OBJCOPY) --dump-section .export_symbol=$(OBJ_DIR)/syms $@
>  
>  $(OBJ_DIR)/$(TARGET): $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O)
>       $(LD) -r $(LDFLAGS) $(OBJ_DIR)/$(TARGET)-kern.o $(APP_O) $(LDLIBS) -o 
> $@.o
> -     $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* -G _start $@.o $@.o
> +     $(OBJCOPY) -w -G $(GLOBAL_PREFIX)* -G _start 
> --remove-section=.export_symbol $@.o $@.o
>       $(LD) $(LDFLAGS) $(LDFLAGS_FINAL) $@.o $(EXTRA_OBJS) -o $@-debug
>       strip -s $@-debug -o $@
>       gzip -n -f -9 -c $@-debug >$@-debug.gz
> diff --git a/include/export.h b/include/export.h
> new file mode 100644
> index 00000000..7140ac68
> --- /dev/null
> +++ b/include/export.h
> @@ -0,0 +1,10 @@
> +#ifndef _EXPORT_H_
> +#define _EXPORT_H_
> +
> +/* Mark a symbol to be visible for apps and libs. */
> +#define EXPORT_SYMBOL(sym)          \
> +    asm(".section .export_symbol\n" \
> +        ".ascii \""#sym"\\n\"\n"    \
> +        ".previous\n")
> +
> +#endif /* _EXPORT_H_ */
> diff --git a/include/lib.h b/include/lib.h
> index dd68985a..abd4e9ab 100644
> --- a/include/lib.h
> +++ b/include/lib.h
> @@ -53,6 +53,7 @@
>  #include <stddef.h>
>  #include <xen/xen.h>
>  #include <xen/event_channel.h>
> +#include <mini-os/export.h>
>  #include "gntmap.h"
>  
>  #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> -- 
> 2.35.3
> 

-- 
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.