From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1D377654 for ; Thu, 6 Oct 2022 06:50:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5C8EBC433C1; Thu, 6 Oct 2022 06:49:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1665039002; bh=8znyUi7frmFRBSfuJybw+EkaJdAE56P9QcmLz7WlrfU=; h=From:To:Cc:Subject:Date:From; b=nzw9aL84H/hEuWBrmMCqO7iVRhyDMlG92G8VdzvEhwA5J7VnKKgTXIZxr9alq5saR eOsn40rDosNmHBJ1201GllDNCWXi4+vICrBWr823ZlLxzX/eU9rho7b9itXQlT1wCK nobAVA+SB7ec/EHF/A71eObffcMnDWHOmGybB+seGnp/tDeaocq+6SwiXQ3rQGPzVH yMK7dEzF5BBfG2SxbACWCycSX2pR8P/b4Tg37hmYy5uWkTW3I2BLVp0YKwiKFOdZ3r hpcN/v4b3nKwY8kRZy3Fos+F4hcmgk22kt0cshIcfa3bu+wl340nJeY9ZZ4wYKcrqq WJd0IXmW3VOxQ== From: Jisheng Zhang 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 Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH] riscv: jump_label: mark arguments as const to satisfy asm constraints Date: Thu, 6 Oct 2022 14:40:28 +0800 Message-Id: <20221006064028.548-1-jszhang@kernel.org> X-Mailer: git-send-email 2.37.2 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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. [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" -- 2.37.2