Hi Charlie,
On Wed, Mar 19, 2025 at 11:35:20AM -0700, Charlie Jenkins wrote:
> Implement the runtime constant infrastructure for riscv. Use this
> infrastructure to generate constants to be used by the d_hash()
> function.
>
> This is the riscv variant of commit 94a2bc0f611c ("arm64: add 'runtime
> constant' support") and commit e3c92e81711d ("runtime constants: add
> x86 architecture support").
>
> Signed-off-by: Charlie Jenkins <char...@rivosinc.com>
> Reviewed-by: Alexandre Ghiti <alexgh...@rivosinc.com>
...
> diff --git a/arch/riscv/include/asm/runtime-const.h
> b/arch/riscv/include/asm/runtime-const.h
...
> +#define RISCV_RUNTIME_CONST_64_ZBA \
> + ".option push\n\t" \
> + ".option arch,+zba\n\t" \
> + "slli %[__tmp],%[__tmp],32\n\t" \
> + "add.uw %[__ret],%[__ret],%[__tmp]\n\t" \
> + "nop\n\t" \
> + "nop\n\t" \
> + ".option pop\n\t" \
...
> +#if defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_RISCV_ISA_ZBKB)
...
> +#elif defined(CONFIG_RISCV_ISA_ZBA)
> +#define runtime_const_ptr(sym)
> \
> +({ \
> + typeof(sym) __ret, __tmp; \
> + asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
> + ALTERNATIVE( \
> + RISCV_RUNTIME_CONST_64_BASE, \
> + RISCV_RUNTIME_CONST_64_ZBA, \
> + 0, RISCV_ISA_EXT_ZBA, 1 \
> + ) \
> + RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
> + : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
> + __ret; \
> +})
This breaks the build for clang versions 16 and earlier because they do
not support '.option arch' and it is used in CONFIG_RISCV_ISA_ZBA, which
has no dependencies and it is default on.
$ make -skj"$(nproc)" ARCH=riscv LLVM=1 mrproper defconfig fs/dcache.o
fs/dcache.c:117:9: warning: unknown option, expected 'push', 'pop', 'rvc',
'norvc', 'relax' or 'norelax' [-Winline-asm]
return runtime_const_ptr(dentry_hashtable) +
^
arch/riscv/include/asm/runtime-const.h:103:4: note: expanded from macro
'runtime_const_ptr'
RISCV_RUNTIME_CONST_64_ZBA, \
^
arch/riscv/include/asm/runtime-const.h:57:17: note: expanded from macro
'RISCV_RUNTIME_CONST_64_ZBA'
".option push\n\t" \
^
<inline asm>:32:10: note: instantiated into assembly here
.option arch,+zba
^
fs/dcache.c:117:9: error: instruction requires the following: 'Zba' (Address
Generation Instructions)
return runtime_const_ptr(dentry_hashtable) +
^
arch/riscv/include/asm/runtime-const.h:103:4: note: expanded from macro
'runtime_const_ptr'
RISCV_RUNTIME_CONST_64_ZBA, \
^
arch/riscv/include/asm/runtime-const.h:59:30: note: expanded from macro
'RISCV_RUNTIME_CONST_64_ZBA'
"slli %[__tmp],%[__tmp],32\n\t" \
^
<inline asm>:34:2: note: instantiated into assembly here
add.uw a2,a2,a3
^
...
$ rg 'OPTION_ARCH|ZBA' .config
364:CONFIG_RISCV_ISA_ZBA=y
Should it grow a dependency on AS_HAS_OPTION_ARCH or should there be a
different fix?
Cheers,
Nathan
