| Message ID | 20180311123815.17916-3-ard.biesheuvel@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, 11 Mar 2018, Ard Biesheuvel wrote: > To allow existing C code to be incorporated into the decompressor or > the UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx > declarations into nops, and #define it in places where such exports > are undesirable. Note that this gets rid of a rather dodgy redefine > of linux/export.h's header guard. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org> > --- > arch/x86/boot/compressed/kaslr.c | 5 +---- > drivers/firmware/efi/libstub/Makefile | 3 ++- > include/linux/export.h | 11 ++++++++++- > 3 files changed, 13 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c > index 8199a6187251..3a2a6d7049e4 100644 > --- a/arch/x86/boot/compressed/kaslr.c > +++ b/arch/x86/boot/compressed/kaslr.c > @@ -23,11 +23,8 @@ > * _ctype[] in lib/ctype.c is needed by isspace() of linux/ctype.h. > * While both lib/ctype.c and lib/cmdline.c will bring EXPORT_SYMBOL > * which is meaningless and will cause compiling error in some cases. > - * So do not include linux/export.h and define EXPORT_SYMBOL(sym) > - * as empty. > */ > -#define _LINUX_EXPORT_H > -#define EXPORT_SYMBOL(sym) > +#define __DISABLE_EXPORTS > > #include "misc.h" > #include "error.h" > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index 7b3ba40f0745..896a882c89f4 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt > KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ > -D__NO_FORTIFY \ > $(call cc-option,-ffreestanding) \ > - $(call cc-option,-fno-stack-protector) > + $(call cc-option,-fno-stack-protector) \ > + -D__DISABLE_EXPORTS > > GCOV_PROFILE := n > KASAN_SANITIZE := n > diff --git a/include/linux/export.h b/include/linux/export.h > index 1a1dfdb2a5c6..25005b55b079 100644 > --- a/include/linux/export.h > +++ b/include/linux/export.h > @@ -72,7 +72,16 @@ extern struct module __this_module; > __attribute__((section("___ksymtab" sec "+" #sym), used)) \ > = { (unsigned long)&sym, __kstrtab_##sym } > > -#if defined(__KSYM_DEPS__) > +#if defined(__DISABLE_EXPORTS) > + > +/* > + * Allow symbol exports to be disabled completely so that C code may > + * be reused in other execution contexts such as the UEFI stub or the > + * decompressor. > + */ > +#define __EXPORT_SYMBOL(sym, sec) > + > +#elif defined(__KSYM_DEPS__) > > /* > * For fine grained build dependencies, we want to tell the build system > -- > 2.15.1 > >
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 8199a6187251..3a2a6d7049e4 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -23,11 +23,8 @@ * _ctype[] in lib/ctype.c is needed by isspace() of linux/ctype.h. * While both lib/ctype.c and lib/cmdline.c will bring EXPORT_SYMBOL * which is meaningless and will cause compiling error in some cases. - * So do not include linux/export.h and define EXPORT_SYMBOL(sym) - * as empty. */ -#define _LINUX_EXPORT_H -#define EXPORT_SYMBOL(sym) +#define __DISABLE_EXPORTS #include "misc.h" #include "error.h" diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 7b3ba40f0745..896a882c89f4 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ -D__NO_FORTIFY \ $(call cc-option,-ffreestanding) \ - $(call cc-option,-fno-stack-protector) + $(call cc-option,-fno-stack-protector) \ + -D__DISABLE_EXPORTS GCOV_PROFILE := n KASAN_SANITIZE := n diff --git a/include/linux/export.h b/include/linux/export.h index 1a1dfdb2a5c6..25005b55b079 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -72,7 +72,16 @@ extern struct module __this_module; __attribute__((section("___ksymtab" sec "+" #sym), used)) \ = { (unsigned long)&sym, __kstrtab_##sym } -#if defined(__KSYM_DEPS__) +#if defined(__DISABLE_EXPORTS) + +/* + * Allow symbol exports to be disabled completely so that C code may + * be reused in other execution contexts such as the UEFI stub or the + * decompressor. + */ +#define __EXPORT_SYMBOL(sym, sec) + +#elif defined(__KSYM_DEPS__) /* * For fine grained build dependencies, we want to tell the build system
To allow existing C code to be incorporated into the decompressor or the UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx declarations into nops, and #define it in places where such exports are undesirable. Note that this gets rid of a rather dodgy redefine of linux/export.h's header guard. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/x86/boot/compressed/kaslr.c | 5 +---- drivers/firmware/efi/libstub/Makefile | 3 ++- include/linux/export.h | 11 ++++++++++- 3 files changed, 13 insertions(+), 6 deletions(-)