[PATCH v2] RISC-V: Stop emitting attributes

[Palmer Dabbelt]

The RISC-V ELF attributes don't contain any useful information.  New
toolchains ignore them, but they frequently trip up various older/mixed
toolchains.  So just turn them off.

Signed-off-by: Palmer Dabbelt <palmer at rivosinc.com>
---
Changes since v1 <20230223195112.10489-1-palmer at rivosinc.com/>:

* Add the attributes to both KBUILD_CFLAGS and KBUILD_AFLAGS, so
  assembly files build without attributes.
* Set COMPAT_CFLAGS so the compat VDSO builds without attributes.
---
 arch/riscv/Makefile                    | 7 +++++++
 arch/riscv/kernel/compat_vdso/Makefile | 4 ++++
 2 files changed, 11 insertions(+)

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 76989561566b..7b53f0be56b2 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -81,6 +81,13 @@ ifeq ($(CONFIG_PERF_EVENTS),y)
         KBUILD_CFLAGS += -fno-omit-frame-pointer
 endif
 
+# The RISC-V attributes frequently cause compatibility issues and provide no
+# information, so just turn them off.
+KBUILD_CFLAGS += $(call cc-option,-mno-riscv-attribute)
+KBUILD_AFLAGS += $(call cc-option,-mno-riscv-attribute)
+KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
+KBUILD_AFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
+
 KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax)
 KBUILD_AFLAGS_MODULE += $(call as-option,-Wa$(comma)-mno-relax)
 
diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile
index 260daf3236d3..7f34f3c7c882 100644
--- a/arch/riscv/kernel/compat_vdso/Makefile
+++ b/arch/riscv/kernel/compat_vdso/Makefile
@@ -14,6 +14,10 @@ COMPAT_LD := $(LD)
 COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
 COMPAT_LD_FLAGS := -melf32lriscv
 
+# Disable attributes, as they're useless and break the build.
+COMPAT_CC_FLAGS += $(call cc-option,-mno-riscv-attribute)
+COMPAT_CC_FLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
+
 # Files to link into the compat_vdso
 obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o
 
-- 
2.39.1