MIPS: Truncate link address into 32bit for 32bit kernel

[ Upstream commit ff487d41 ]

LLD failed to link vmlinux with 64bit load address for 32bit ELF
while bfd will strip 64bit address into 32bit silently.
To fix LLD build, we should truncate load address provided by platform
into 32bit for 32bit kernel.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/786
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=25784Reviewed-by: Fangrui Song <maskray@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

arch/mips/Makefile

@@ -256,12 +256,23 @@ ifdef CONFIG_64BIT
   endif
 endif
 
+# When linking a 32-bit executable the LLVM linker cannot cope with a
+# 32-bit load address that has been sign-extended to 64 bits.  Simply
+# remove the upper 32 bits then, as it is safe to do so with other
+# linkers.
+ifdef CONFIG_64BIT
+	load-ld			= $(load-y)
+else
+	load-ld			= $(subst 0xffffffff,0x,$(load-y))
+endif
+
 KBUILD_AFLAGS	+= $(cflags-y)
 KBUILD_CFLAGS	+= $(cflags-y)
-KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y)
+KBUILD_CPPFLAGS += -DVMLINUX_LOAD_ADDRESS=$(load-y) -DLINKER_LOAD_ADDRESS=$(load-ld)
 KBUILD_CPPFLAGS += -DDATAOFFSET=$(if $(dataoffset-y),$(dataoffset-y),0)
 
 bootvars-y	= VMLINUX_LOAD_ADDRESS=$(load-y) \
+		  LINKER_LOAD_ADDRESS=$(load-ld) \
 		  VMLINUX_ENTRY_ADDRESS=$(entry-y) \
 		  PLATFORM="$(platform-y)"
 ifdef CONFIG_32BIT

arch/mips/boot/compressed/Makefile

@@ -87,7 +87,7 @@ ifneq ($(zload-y),)
 VMLINUZ_LOAD_ADDRESS := $(zload-y)
 else
 VMLINUZ_LOAD_ADDRESS = $(shell $(obj)/calc_vmlinuz_load_addr \
-		$(obj)/vmlinux.bin $(VMLINUX_LOAD_ADDRESS))
+		$(obj)/vmlinux.bin $(LINKER_LOAD_ADDRESS))
 endif
 
 vmlinuzobjs-y += $(obj)/piggy.o

arch/mips/kernel/vmlinux.lds.S

@@ -49,7 +49,7 @@ SECTIONS
 	/* . = 0xa800000000300000; */
 	. = 0xffffffff80300000;
 #endif
-	. = VMLINUX_LOAD_ADDRESS;
+	. = LINKER_LOAD_ADDRESS;
 	/* read-only */
 	_text = .;	/* Text and read-only data */
 	.text : {