From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CFE7623A2 for ; Tue, 11 Oct 2022 07:32:57 +0000 (UTC) Received: from p5b127dea.dip0.t-ipconnect.de ([91.18.125.234] helo=phil.localnet) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oi9kd-0007DL-OH; Tue, 11 Oct 2022 09:32:31 +0200 From: Heiko Stuebner To: Peter Zijlstra , Josh Poimboeuf , Jason Baron , Steven Rostedt , Ard Biesheuvel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Nathan Chancellor , Nick Desaulniers , Tom Rix , Samuel Holland , linux-riscv@lists.infradead.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Jisheng Zhang Subject: Re: [PATCH] riscv: jump_label: mark arguments as const to satisfy asm constraints Date: Tue, 11 Oct 2022 09:32:30 +0200 Message-ID: <2432835.C4sosBPzcN@phil> In-Reply-To: <20221006064028.548-1-jszhang@kernel.org> References: <20221006064028.548-1-jszhang@kernel.org> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" 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 : > ./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 > [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 > --- > 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" >