| Message ID | 20180102200549.22984-3-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | add support for relative references in special sections | expand |
On Tue, 2 Jan 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. [...] > --- a/include/linux/export.h > +++ b/include/linux/export.h > @@ -83,6 +83,15 @@ extern struct module __this_module; > */ > #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym === > > +#elif 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) > + I think you should rather put this first thing in the #if sequence so to override the defined(__KSYM_DEPS__) case too. No need to create build dependencies for module symbols that you're going to stub out afterwards anyway. Nicolas
On 2 January 2018 at 23:47, Nicolas Pitre <nicolas.pitre@linaro.org> wrote: > On Tue, 2 Jan 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. > [...] > >> --- a/include/linux/export.h >> +++ b/include/linux/export.h >> @@ -83,6 +83,15 @@ extern struct module __this_module; >> */ >> #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym === >> >> +#elif 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) >> + > > I think you should rather put this first thing in the #if sequence so to > override the defined(__KSYM_DEPS__) case too. No need to create build > dependencies for module symbols that you're going to stub out > afterwards anyway. > I wasn't sure, so thanks for clearing that up.
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 adaa4a964f0c..312bd0b64a61 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..6dba2fb08f77 100644 --- a/include/linux/export.h +++ b/include/linux/export.h @@ -83,6 +83,15 @@ extern struct module __this_module; */ #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym === +#elif 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(CONFIG_TRIM_UNUSED_KSYMS) #include <generated/autoksyms.h>
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. Cc: matt@codeblueprint.co.uk Cc: keescook@chromium.org Cc: jeyu@kernel.org 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 | 9 +++++++++ 3 files changed, 12 insertions(+), 5 deletions(-) -- 2.11.0