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riscv: fix detection of toolchain Zihintpause support

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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: 8eb060e101 ("arch/riscv: add Zihintpause support")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20221006173520.1785507-3-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Conor Dooley 2022-10-06 18:35:21 +01:00 committed by Palmer Dabbelt
parent b8c86872d1
commit aae538cd03
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GPG Key ID: 2E1319F35FBB1889
3 changed files with 9 additions and 3 deletions
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7
arch/riscv/Kconfig
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@ -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

3
arch/riscv/Makefile
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@ -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)

2
arch/riscv/include/asm/vdso/processor.h
View File

@ -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 */