[PATCH v4 3/3] riscv: fix building compressed EFI image

[Dmitry Antipov]

When building vmlinuz.efi with CONFIG_EFI_ZBOOT enabled,
'__lshrdi3()' is also needed to fix yet another link error:

riscv32-linux-gnu-ld: drivers/firmware/efi/libstub/lib-cmdline.stub.o: in function `__efistub_.L49':
__efistub_cmdline.c:(.init.text+0x202): undefined reference to `__efistub___lshrdi3'

And since riscv64 can have CONFIG_EFI_ZBOOT but doesn't need these
library routines, introduce CONFIG_EFI_ZBOOT_USE_LIBGCC to manage
linking of lib-ashldi3.o and lib-lshrdi3.o on riscv32 only.

Reported-by: Charlie Jenkins <thecharlesjenkins at gmail.com>
Closes: https://lore.kernel.org/linux-riscv/20260409050018.GA371560@inky.localdomain
Tested-by: Charlie Jenkins <thecharlesjenkins at gmail.com>
Signed-off-by: Dmitry Antipov <dmantipov at yandex.ru>
---
v4: use more meaningful CONFIG_EFI_ZBOOT_USE_LIBGCC and adjust tags (Andy)
v3: initial version to join the series
---
 drivers/firmware/efi/Kconfig          | 4 ++++
 drivers/firmware/efi/libstub/Makefile | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 29e0729299f5b..e1483e20c69b9 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -85,6 +85,10 @@ config EFI_ZBOOT
 	  provided that the loader implements the decompression algorithm.
 	  (The compression algorithm used is described in the zboot header)
 
+config EFI_ZBOOT_USE_LIBGCC
+	bool
+	default y if RISCV && 32BIT
+
 config EFI_ARMSTUB_DTB_LOADER
 	bool "Enable the DTB loader"
 	depends on EFI_GENERIC_STUB && !RISCV && !LOONGARCH
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index e386ffd009b7e..91cefa80c158f 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -96,7 +96,8 @@ CFLAGS_zboot-decompress-gzip.o	+= -I$(srctree)/lib/zlib_inflate
 zboot-obj-$(CONFIG_KERNEL_ZSTD)	:= zboot-decompress-zstd.o lib-xxhash.o
 CFLAGS_zboot-decompress-zstd.o	+= -I$(srctree)/lib/zstd
 
-zboot-obj-$(CONFIG_RISCV)	+= lib-clz_ctz.o lib-ashldi3.o
+zboot-libgcc-obj-$(CONFIG_EFI_ZBOOT_USE_LIBGCC) += lib-ashldi3.o lib-lshrdi3.o
+zboot-obj-$(CONFIG_RISCV)	+= lib-clz_ctz.o $(zboot-libgcc-obj-y)
 lib-$(CONFIG_EFI_ZBOOT)		+= zboot.o $(zboot-obj-y)
 
 lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o
-- 
2.53.0