On Wed, Jul 08, 2020 at 11:50:19AM -0700, Nick Terrell wrote: > From: Nick Terrell <terrelln@xxxxxx> > > * Add unzstd() and the zstd decompress interface. > * Add zstd support to decompress_method(). > > The decompress_method() and unzstd() functions are used to decompress > the initramfs and the initrd. The __decompress() function is used in > the preboot environment to decompress a zstd compressed kernel. > > The zstd decompression function allows the input and output buffers to > overlap because that is used by x86 kernel decompression. > > Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> > Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> > Signed-off-by: Nick Terrell <terrelln@xxxxxx> > + * > + * __DISABLE_EXPORTS stops zstd and xxhash from declaring themselves > + * as modules by disabling the EXPORT_SYMBOL macro. > + */ Hi Nick, this doesn't actually work, because misc.c includes export.h via "misc.h" -> <linux/linkage.h> -> <linux/export.h> and EXPORT_SYMBOL is already defined before __DISABLE_EXPORTS is defined here. Adding -D__EXPORT_SYMBOLS to KBUILD_CFLAGS in arch/x86/boot/compressed/Makefile fixes that, and then you don't have to define it here. Also, __DISABLE_EXPORTS does not currently inhibit MODULE_INFO, so a .modinfo section gets emitted into misc.o. I *think* this is harmless and it will get discarded when building compressed/vmlinux, but thought I'd point it out.
