Unverified Commit aae538cd authored by Conor Dooley's avatar Conor Dooley Committed by Palmer Dabbelt
Browse files

riscv: fix detection of toolchain Zihintpause support 



It is not sufficient to check if a toolchain supports a particular
extension without checking if the linker supports that extension
too. For example, Clang 15 supports Zihintpause but GNU bintutils
2.35.2 does not, leading build errors like so:

riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zihintpause2p0: Invalid or unknown z ISA extension: 'zihintpause'

Add a TOOLCHAIN_HAS_ZIHINTPAUSE which checks if each of the compiler,
assembler and linker support the extension. Replace the ifdef in the
vdso with one depending on this new symbol.

Fixes: 8eb060e1 ("arch/riscv: add Zihintpause support")
Signed-off-by: default avatarConor Dooley <conor.dooley@microchip.com>
Reviewed-by: default avatarHeiko Stuebner <heiko@sntech.de>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20221006173520.1785507-3-conor@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent b8c86872

arch/riscv/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -425,6 +425,13 @@ config RISCV_ISA_ZICBOM 


	   If you don't know what to do here, say Y.



config TOOLCHAIN_HAS_ZIHINTPAUSE

	bool

	default y

	depends on !64BIT || $(cc-option,-mabi=lp64 -march=rv64ima_zihintpause)

	depends on !32BIT || $(cc-option,-mabi=ilp32 -march=rv32ima_zihintpause)

	depends on LLD_VERSION >= 150000 || LD_VERSION >= 23600



config FPU

	bool "FPU support"

	default y

arch/riscv/Makefile

+1 −2
Original line number Diff line number Diff line
@@ -60,8 +60,7 @@ riscv-march-$(toolchain-need-zicsr-zifencei) := $(riscv-march-y)_zicsr_zifencei 
riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZICBOM) := $(riscv-march-y)_zicbom



# Check if the toolchain supports Zihintpause extension

toolchain-supports-zihintpause := $(call cc-option-yn, -march=$(riscv-march-y)_zihintpause)

riscv-march-$(toolchain-supports-zihintpause) := $(riscv-march-y)_zihintpause

riscv-march-$(CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE) := $(riscv-march-y)_zihintpause



KBUILD_CFLAGS += -march=$(subst fd,,$(riscv-march-y))

KBUILD_AFLAGS += -march=$(riscv-march-y)

arch/riscv/include/asm/vdso/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ static inline void cpu_relax(void) 
		 * Reduce instruction retirement.

		 * This assumes the PC changes.

		 */

#ifdef __riscv_zihintpause

#ifdef CONFIG_TOOLCHAIN_HAS_ZIHINTPAUSE

		__asm__ __volatile__ ("pause");

#else

		/* Encoding of the pause instruction */