From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 61E84CE79AC for ; Wed, 20 Sep 2023 07:40:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3QqhLLkIrvv4jQeroy9SN4cf2w70AShByoC8bNquN94=; b=kns+aUTqTZfkYx 5W4akNVsaV1m0drCwvXcq5ZmFT0KUtM8fISIqkz5R52R+QcJl7X9TRMJ2njkCEnhthrKNtZisY96f wpX5et5gLVAZto3j1DwQTl+OS6M/m3ekx00wr8vvrGXn2LuwUfxvFKPNLWyOvPDa8lgSxr64oQsbW Dcq/l+BOzLendCeiB0fjd3k+Ej5SPj6beTWUDI3BwJJn6nR0d4Uf9CA1CFvWIqZ61op7V9I0Bk5DZ +vVayXaxkjHaQeGFIsOH+KA7aCYJ9s6w8aT+mhLLbSDO+1FbU7pkIXyIxaF8uB0eXuYdz6YILWbAU 0VU9fR+6ok0wGWFRFiNw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qiroR-0029nc-1b; Wed, 20 Sep 2023 07:39:55 +0000 Received: from mgamail.intel.com ([134.134.136.100]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qiroO-0029m5-0P for linux-riscv@lists.infradead.org; Wed, 20 Sep 2023 07:39:53 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1695195592; x=1726731592; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=D6J5R/1H9NYmwj1HBb/6nCFtRveDV5ws9Ss+Z61Hsv4=; b=fhp0BFxid/4XCiwEPDP+PyK6jr6iUmAtZlYzy6B4LlnX7IakwrbWLJXs Kpam+GJdGGy91RwkQbYf8P8IarAwFIgiX65ZaEPmUw1KcNTnEqRTIDNAv N/nS/7HW8rUW+Rqj8D6AraxDoo4/RCfSS3Ve8LN7hbqnTHGVhopNmGvrc Ce4ZC1xUoQkyUCEpecEWN9AUIDYSaGwBy3qKSna3ElhR5g3dyS1UUH7H+ 5uirz3w7PKHf/xhPUI8Ws+2YGEJOEI71y1ZVV82ou0Af4FKK7Y1D3np+u zKjos8kIcecBF0AsdwVj2+QuHhHQKCIpkDw4qvk+smjzjmcEA3qTC4suI Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="446622641" X-IronPort-AV: E=Sophos;i="6.02,161,1688454000"; d="scan'208";a="446622641" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Sep 2023 00:39:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="816791848" X-IronPort-AV: E=Sophos;i="6.02,161,1688454000"; d="scan'208";a="816791848" Received: from xiao-desktop.sh.intel.com ([10.239.46.158]) by fmsmga004.fm.intel.com with ESMTP; 20 Sep 2023 00:39:48 -0700 From: Xiao Wang To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, ardb@kernel.org Cc: anup@brainfault.org, haicheng.li@intel.com, ajones@ventanamicro.com, linux-riscv@lists.infradead.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Xiao Wang Subject: [PATCH v2 2/2] riscv: Optimize bitops with Zbb extension Date: Wed, 20 Sep 2023 15:46:53 +0800 Message-Id: <20230920074653.2509631-3-xiao.w.wang@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230920074653.2509631-1-xiao.w.wang@intel.com> References: <20230920074653.2509631-1-xiao.w.wang@intel.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230920_003952_208194_1A853D9A X-CRM114-Status: GOOD ( 20.38 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org This patch leverages the alternative mechanism to dynamically optimize bitops (including __ffs, __fls, ffs, fls) with Zbb instructions. When Zbb ext is not supported by the runtime CPU, legacy implementation is used. If Zbb is supported, then the optimized variants will be selected via alternative patching. The legacy bitops support is taken from the generic C implementation as fallback. If the parameter is a build-time constant, we leverage compiler builtin to calculate the result directly, this approach is inspired by x86 bitops implementation. EFI stub runs before the kernel, so alternative mechanism should not be used there, this patch introduces a macro NO_ALTERNATIVE for this purpose. Signed-off-by: Xiao Wang --- arch/riscv/include/asm/bitops.h | 266 +++++++++++++++++++++++++- drivers/firmware/efi/libstub/Makefile | 2 +- 2 files changed, 264 insertions(+), 4 deletions(-) diff --git a/arch/riscv/include/asm/bitops.h b/arch/riscv/include/asm/bitops.h index 3540b690944b..c97e774cb647 100644 --- a/arch/riscv/include/asm/bitops.h +++ b/arch/riscv/include/asm/bitops.h @@ -15,13 +15,273 @@ #include #include +#if !defined(CONFIG_RISCV_ISA_ZBB) || defined(NO_ALTERNATIVE) #include -#include -#include #include +#include +#include + +#else +#include +#include + +#if (BITS_PER_LONG == 64) +#define CTZW "ctzw " +#define CLZW "clzw " +#elif (BITS_PER_LONG == 32) +#define CTZW "ctz " +#define CLZW "clz " +#else +#error "Unexpected BITS_PER_LONG" +#endif + +static __always_inline unsigned long variable__ffs(unsigned long word) +{ + int num; + + asm_volatile_goto( + ALTERNATIVE("j %l[legacy]", "nop", 0, RISCV_ISA_EXT_ZBB, 1) + : : : : legacy); + + asm volatile ( + ".option push\n" + ".option arch,+zbb\n" + "ctz %0, %1\n" + ".option pop\n" + : "=r" (word) : "r" (word) :); + + return word; + +legacy: + num = 0; +#if BITS_PER_LONG == 64 + if ((word & 0xffffffff) == 0) { + num += 32; + word >>= 32; + } +#endif + if ((word & 0xffff) == 0) { + num += 16; + word >>= 16; + } + if ((word & 0xff) == 0) { + num += 8; + word >>= 8; + } + if ((word & 0xf) == 0) { + num += 4; + word >>= 4; + } + if ((word & 0x3) == 0) { + num += 2; + word >>= 2; + } + if ((word & 0x1) == 0) + num += 1; + return num; +} + +/** + * __ffs - find first set bit in a long word + * @word: The word to search + * + * Undefined if no set bit exists, so code should check against 0 first. + */ +#define __ffs(word) \ + (__builtin_constant_p(word) ? \ + (unsigned long)__builtin_ctzl(word) : \ + variable__ffs(word)) + +static __always_inline unsigned long variable__fls(unsigned long word) +{ + int num; + + asm_volatile_goto( + ALTERNATIVE("j %l[legacy]", "nop", 0, RISCV_ISA_EXT_ZBB, 1) + : : : : legacy); + + asm volatile ( + ".option push\n" + ".option arch,+zbb\n" + "clz %0, %1\n" + ".option pop\n" + : "=r" (word) : "r" (word) :); + + return BITS_PER_LONG - 1 - word; + +legacy: + num = BITS_PER_LONG - 1; +#if BITS_PER_LONG == 64 + if (!(word & (~0ul << 32))) { + num -= 32; + word <<= 32; + } +#endif + if (!(word & (~0ul << (BITS_PER_LONG-16)))) { + num -= 16; + word <<= 16; + } + if (!(word & (~0ul << (BITS_PER_LONG-8)))) { + num -= 8; + word <<= 8; + } + if (!(word & (~0ul << (BITS_PER_LONG-4)))) { + num -= 4; + word <<= 4; + } + if (!(word & (~0ul << (BITS_PER_LONG-2)))) { + num -= 2; + word <<= 2; + } + if (!(word & (~0ul << (BITS_PER_LONG-1)))) + num -= 1; + return num; +} + +/** + * __fls - find last set bit in a long word + * @word: the word to search + * + * Undefined if no set bit exists, so code should check against 0 first. + */ +#define __fls(word) \ + (__builtin_constant_p(word) ? \ + (unsigned long)(BITS_PER_LONG - 1 - __builtin_clzl(word)) : \ + variable__fls(word)) + +static __always_inline int variable_ffs(int x) +{ + int r; + + asm_volatile_goto( + ALTERNATIVE("j %l[legacy]", "nop", 0, RISCV_ISA_EXT_ZBB, 1) + : : : : legacy); + + asm volatile ( + ".option push\n" + ".option arch,+zbb\n" + "bnez %1, 1f\n" + "li %0, 0\n" + "j 2f\n" + "1:\n" + CTZW "%0, %1\n" + "addi %0, %0, 1\n" + "2:\n" + ".option pop\n" + : "=r" (r) : "r" (x) :); + + return r; + +legacy: + r = 1; + if (!x) + return 0; + if (!(x & 0xffff)) { + x >>= 16; + r += 16; + } + if (!(x & 0xff)) { + x >>= 8; + r += 8; + } + if (!(x & 0xf)) { + x >>= 4; + r += 4; + } + if (!(x & 3)) { + x >>= 2; + r += 2; + } + if (!(x & 1)) { + x >>= 1; + r += 1; + } + return r; +} + +/** + * ffs - find first set bit in a word + * @x: the word to search + * + * This is defined the same way as the libc and compiler builtin ffs routines. + * + * ffs(value) returns 0 if value is 0 or the position of the first set bit if + * value is nonzero. The first (least significant) bit is at position 1. + */ +#define ffs(x) (__builtin_constant_p(x) ? __builtin_ffs(x) : variable_ffs(x)) + +static __always_inline int variable_fls(unsigned int x) +{ + int r; + + asm_volatile_goto( + ALTERNATIVE("j %l[legacy]", "nop", 0, RISCV_ISA_EXT_ZBB, 1) + : : : : legacy); + + asm volatile ( + ".option push\n" + ".option arch,+zbb\n" + "bnez %1, 1f\n" + "li %0, 0\n" + "j 2f\n" + "1:\n" + CLZW "%0, %1\n" + "neg %0, %0\n" + "addi %0, %0, 32\n" + "2:\n" + ".option pop\n" + : "=r" (r) : "r" (x) :); + + return r; + +legacy: + r = 32; + if (!x) + return 0; + if (!(x & 0xffff0000u)) { + x <<= 16; + r -= 16; + } + if (!(x & 0xff000000u)) { + x <<= 8; + r -= 8; + } + if (!(x & 0xf0000000u)) { + x <<= 4; + r -= 4; + } + if (!(x & 0xc0000000u)) { + x <<= 2; + r -= 2; + } + if (!(x & 0x80000000u)) { + x <<= 1; + r -= 1; + } + return r; +} + +/** + * fls - find last set bit in a word + * @x: the word to search + * + * This is defined in a similar way as ffs, but returns the position of the most + * significant set bit. + * + * fls(value) returns 0 if value is 0 or the position of the last set bit if + * value is nonzero. The last (most significant) bit is at position 32. + */ +#define fls(x) \ + (__builtin_constant_p(x) ? \ + (int)(((x) != 0) ? \ + (sizeof(unsigned int) * 8 - __builtin_clz(x)) : 0) : \ + variable_fls(x)) + +#endif + +#include #include #include -#include #include diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index a1157c2a7170..d68cacd4e3af 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -28,7 +28,7 @@ cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \ -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \ -DEFI_HAVE_STRCMP -fno-builtin -fpic \ $(call cc-option,-mno-single-pic-base) -cflags-$(CONFIG_RISCV) += -fpic +cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE cflags-$(CONFIG_LOONGARCH) += -fpie cflags-$(CONFIG_EFI_PARAMS_FROM_FDT) += -I$(srctree)/scripts/dtc/libfdt -- 2.25.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv