Messages in this thread | | | From | Heiko Stuebner <> | Subject | Re: [PATCH] riscv: jump_label: mark arguments as const to satisfy asm constraints | Date | Tue, 11 Oct 2022 09:32:30 +0200 |
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Am Donnerstag, 6. Oktober 2022, 08:40:28 CEST schrieb Jisheng Zhang: > Samuel reported that the static branch usage in cpu_relax() breaks > building with CONFIG_CC_OPTIMIZE_FOR_SIZE[1]: > > In file included from <command-line>: > ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax': > ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0 > probably does not match constraints > 285 | #define asm_volatile_goto(x...) asm goto(x) > | ^~~ > ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro > 'asm_volatile_goto' > 41 | asm_volatile_goto( > | ^~~~~~~~~~~~~~~~~ > ././include/linux/compiler_types.h:285:33: error: impossible constraint > in 'asm' > 285 | #define asm_volatile_goto(x...) asm goto(x) > | ^~~ > ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro > 'asm_volatile_goto' > 41 | asm_volatile_goto( > | ^~~~~~~~~~~~~~~~~ > make[1]: *** [scripts/Makefile.build:249: > arch/riscv/kernel/vdso/vgettimeofday.o] Error 1 > make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2 > > Maybe "-Os" prevents GCC from detecting that the key/branch arguments > can be treated as constants and used as immediate operands. Inspired > by x86's commit 864b435514b2("x86/jump_label: Mark arguments as const to > satisfy asm constraints"), and as pointed out by Steven in [2] "The "i" > constraint needs to be a constant.", let's do similar modifications to > riscv. > > Tested by CC_OPTIMIZE_FOR_SIZE + gcc and CC_OPTIMIZE_FOR_SIZE + clang.
I ran into the same build-issue when enabling CC_OPTIMIZE_FOR_SIZE and this patch fixes it, so
Tested-by: Heiko Stuebner <heiko@sntech.de>
> [1]https://lore.kernel.org/linux-riscv/20220922060958.44203-1-samuel@sholland.org/ > [2]https://lore.kernel.org/all/20210212094059.5f8d05e8@gandalf.local.home/ > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > --- > arch/riscv/include/asm/jump_label.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h > index 38af2ec7b9bf..6d58bbb5da46 100644 > --- a/arch/riscv/include/asm/jump_label.h > +++ b/arch/riscv/include/asm/jump_label.h > @@ -14,8 +14,8 @@ > > #define JUMP_LABEL_NOP_SIZE 4 > > -static __always_inline bool arch_static_branch(struct static_key *key, > - bool branch) > +static __always_inline bool arch_static_branch(struct static_key * const key, > + const bool branch) > { > asm_volatile_goto( > " .option push \n\t" > @@ -35,8 +35,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, > return true; > } > > -static __always_inline bool arch_static_branch_jump(struct static_key *key, > - bool branch) > +static __always_inline bool arch_static_branch_jump(struct static_key * const key, > + const bool branch) > { > asm_volatile_goto( > " .option push \n\t" >
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