From 8abe7fc26ad8f28bfdf78adbed56acd1fa93f82d Mon Sep 17 00:00:00 2001 From: John Millikin Date: Thu, 25 Mar 2021 17:04:33 -0700 Subject: [PATCH 1/4] x86/build: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When cross-compiling with Clang, the `$(CLANG_FLAGS)' variable contains additional flags needed to build C and assembly sources for the target platform. Normally this variable is automatically included in `$(KBUILD_CFLAGS)' via the top-level Makefile. The x86 real-mode makefile builds `$(REALMODE_CFLAGS)' from a plain assignment and therefore drops the Clang flags. This causes Clang to not recognize x86-specific assembler directives:   arch/x86/realmode/rm/header.S:36:1: error: unknown directive   .type real_mode_header STT_OBJECT ; .size real_mode_header, .-real_mode_header   ^ Explicit propagation of `$(CLANG_FLAGS)' to `$(REALMODE_CFLAGS)', which is inherited by real-mode make rules, fixes cross-compilation with Clang for x86 targets. Relevant flags: * `--target' sets the target architecture when cross-compiling. This   flag must be set for both compilation and assembly (`KBUILD_AFLAGS')   to support architecture-specific assembler directives. * `-no-integrated-as' tells clang to assemble with GNU Assembler   instead of its built-in LLVM assembler. This flag is set by default   unless `LLVM_IAS=1' is set, because the LLVM assembler can't yet   parse certain GNU extensions. Signed-off-by: John Millikin Signed-off-by: Nathan Chancellor Signed-off-by: Borislav Petkov Acked-by: Ard Biesheuvel Tested-by: Sedat Dilek Link: https://lkml.kernel.org/r/20210326000435.4785-2-nathan@kernel.org --- arch/x86/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 2d6d5a28c3bf..9a73e0cea19c 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -33,6 +33,7 @@ REALMODE_CFLAGS += -ffreestanding REALMODE_CFLAGS += -fno-stack-protector REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -Wno-address-of-packed-member) REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4)) +REALMODE_CFLAGS += $(CLANG_FLAGS) export REALMODE_CFLAGS # BITS is used as extension for files which are available in a 32 bit From d5cbd80e302dfea59726c44c56ab7957f822409f Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Thu, 25 Mar 2021 17:04:34 -0700 Subject: [PATCH 2/4] x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGS When cross compiling x86 on an ARM machine with clang, there are several errors along the lines of: arch/x86/include/asm/string_64.h:27:10: error: invalid output constraint '=&c' in asm This happens because the compressed boot Makefile reassigns KBUILD_CFLAGS and drops the clang flags that set the target architecture ('--target=') and the path to the GNU cross tools ('--prefix='), meaning that the host architecture is targeted. These flags are available as $(CLANG_FLAGS) from the main Makefile so add them to the compressed boot folder's KBUILD_CFLAGS so that cross compiling works as expected. Signed-off-by: Nathan Chancellor Signed-off-by: Borislav Petkov Acked-by: Ard Biesheuvel Link: https://lkml.kernel.org/r/20210326000435.4785-3-nathan@kernel.org --- arch/x86/boot/compressed/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index e0bc3988c3fa..6e5522aebbbd 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -46,6 +46,7 @@ KBUILD_CFLAGS += -D__DISABLE_EXPORTS # Disable relocation relaxation in case the link is not PIE. KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mrelax-relocations=no) KBUILD_CFLAGS += -include $(srctree)/include/linux/hidden.h +KBUILD_CFLAGS += $(CLANG_FLAGS) # sev-es.c indirectly inludes inat-table.h which is generated during # compilation and stored in $(objtree). Add the directory to the includes so From 58d746c119dfa28e72fc35aacaf3d2a3ac625cd0 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Thu, 25 Mar 2021 17:04:35 -0700 Subject: [PATCH 3/4] efi/libstub: Add $(CLANG_FLAGS) to x86 flags When cross compiling x86 on an ARM machine with clang, there are several errors along the lines of: arch/x86/include/asm/page_64.h:52:7: error: invalid output constraint '=D' in asm This happens because the x86 flags in the EFI stub are not derived from KBUILD_CFLAGS like the other architectures are and the clang flags that set the target architecture ('--target=') and the path to the GNU cross tools ('--prefix=') are not present, meaning that the host architecture is targeted. These flags are available as $(CLANG_FLAGS) from the main Makefile so add them to the cflags for x86 so that cross compiling works as expected. Signed-off-by: Nathan Chancellor Signed-off-by: Borislav Petkov Acked-by: Ard Biesheuvel Link: https://lkml.kernel.org/r/20210326000435.4785-4-nathan@kernel.org --- drivers/firmware/efi/libstub/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index c23466e05e60..d0537573501e 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -13,7 +13,8 @@ cflags-$(CONFIG_X86) += -m$(BITS) -D__KERNEL__ \ -Wno-pointer-sign \ $(call cc-disable-warning, address-of-packed-member) \ $(call cc-disable-warning, gnu) \ - -fno-asynchronous-unwind-tables + -fno-asynchronous-unwind-tables \ + $(CLANG_FLAGS) # arm64 uses the full KBUILD_CFLAGS so it's necessary to explicitly # disable the stackleak plugin From 0ef3439cd80ba7770723edb0470d15815914bb62 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Wed, 14 Apr 2021 12:38:28 +0200 Subject: [PATCH 4/4] x86/build: Disable HIGHMEM64G selection for M486SX Fix a regression caused by making the 486SX separately selectable in Kconfig, for which the HIGHMEM64G setting has not been updated and therefore has become exposed as a user-selectable option for the M486SX configuration setting unlike with original M486 and all the other settings that choose non-PAE-enabled processors: High Memory Support > 1. off (NOHIGHMEM) 2. 4GB (HIGHMEM4G) 3. 64GB (HIGHMEM64G) choice[1-3?]: With the fix in place the setting is now correctly removed: High Memory Support > 1. off (NOHIGHMEM) 2. 4GB (HIGHMEM4G) choice[1-2?]: [ bp: Massage commit message. ] Fixes: 87d6021b8143 ("x86/math-emu: Limit MATH_EMULATION to 486SX compatibles") Signed-off-by: Maciej W. Rozycki Signed-off-by: Borislav Petkov Cc: stable@vger.kernel.org # v5.5+ Link: https://lkml.kernel.org/r/alpine.DEB.2.21.2104141221340.44318@angie.orcam.me.uk --- arch/x86/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2792879d398e..268b7d5c9835 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1406,7 +1406,7 @@ config HIGHMEM4G config HIGHMEM64G bool "64GB" - depends on !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6 + depends on !M486SX && !M486 && !M586 && !M586TSC && !M586MMX && !MGEODE_LX && !MGEODEGX1 && !MCYRIXIII && !MELAN && !MWINCHIPC6 && !WINCHIP3D && !MK6 select X86_PAE help Select this if you have a 32-bit processor and more than 4