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Signed-off-by: Andrew Cooper Acked-by: Stefano Stabellini --- CC: Jan Beulich CC: Roger Pau Monné CC: Stefano Stabellini CC: Julien Grall CC: Volodymyr Babchuk CC: Bertrand Marquis CC: Michal Orzel CC: Oleksii Kurochko CC: Shawn Anastasio --- xen/include/xen/bitops.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index ed6b9ccc724f..6f8e36f1c755 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -210,6 +210,8 @@ static always_inline bool test_bit(int nr, const volatile void *addr) test_bit(nr, addr); \ }) +/* --------------------- Please tidy above here --------------------- */ + static always_inline attr_const unsigned int ffs(unsigned int x) { if ( __builtin_constant_p(x) ) From patchwork Wed Sep 4 22:55:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Cooper X-Patchwork-Id: 13791482 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 CC996CD4F4B for ; 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Wed, 04 Sep 2024 15:55:37 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , Jan Beulich , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Bertrand Marquis , Michal Orzel , Oleksii Kurochko , Shawn Anastasio Subject: [PATCH v3 2/5] xen/bitops: Drop the remnants of hweight{8,16}() Date: Wed, 4 Sep 2024 23:55:27 +0100 Message-Id: <20240904225530.3888315-3-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240904225530.3888315-1-andrew.cooper3@citrix.com> References: <20240904225530.3888315-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 They are no more. No functional change. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich Acked-by: Stefano Stabellini Acked-by: Shawn Anastasio --- CC: Jan Beulich CC: Roger Pau Monné CC: Stefano Stabellini CC: Julien Grall CC: Volodymyr Babchuk CC: Bertrand Marquis CC: Michal Orzel CC: Oleksii Kurochko CC: Shawn Anastasio --- xen/arch/arm/include/asm/bitops.h | 2 -- xen/arch/ppc/include/asm/bitops.h | 2 -- xen/arch/x86/include/asm/bitops.h | 2 -- xen/include/xen/bitops.h | 17 ----------------- 4 files changed, 23 deletions(-) diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h index 3c023103f734..91cd167b6bbb 100644 --- a/xen/arch/arm/include/asm/bitops.h +++ b/xen/arch/arm/include/asm/bitops.h @@ -86,8 +86,6 @@ bool clear_mask16_timeout(uint16_t mask, volatile void *p, */ #define hweight64(x) generic_hweight64(x) #define hweight32(x) generic_hweight32(x) -#define hweight16(x) generic_hweight16(x) -#define hweight8(x) generic_hweight8(x) #endif /* _ARM_BITOPS_H */ /* diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h index 6e4e112b8b92..64512e949530 100644 --- a/xen/arch/ppc/include/asm/bitops.h +++ b/xen/arch/ppc/include/asm/bitops.h @@ -134,7 +134,5 @@ static inline int test_and_set_bit(unsigned int nr, volatile void *addr) */ #define hweight64(x) __builtin_popcountll(x) #define hweight32(x) __builtin_popcount(x) -#define hweight16(x) __builtin_popcount((uint16_t)(x)) -#define hweight8(x) __builtin_popcount((uint8_t)(x)) #endif /* _ASM_PPC_BITOPS_H */ diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h index 8c0403405aa2..4c5b21907a64 100644 --- a/xen/arch/x86/include/asm/bitops.h +++ b/xen/arch/x86/include/asm/bitops.h @@ -483,7 +483,5 @@ static always_inline unsigned int arch_flsl(unsigned long x) */ #define hweight64(x) generic_hweight64(x) #define hweight32(x) generic_hweight32(x) -#define hweight16(x) generic_hweight16(x) -#define hweight8(x) generic_hweight8(x) #endif /* _X86_BITOPS_H */ diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index 6f8e36f1c755..58c600155f7e 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -413,23 +413,6 @@ static inline unsigned int generic_hweight32(unsigned int w) return (w + (w >> 16)) & 0xff; 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Wed, 04 Sep 2024 15:55:38 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , Jan Beulich , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini , Julien Grall , Volodymyr Babchuk , Bertrand Marquis , Michal Orzel , Oleksii Kurochko , Shawn Anastasio Subject: [PATCH v3 3/5] xen/bitops: Implement hweight32() in terms of hweightl() Date: Wed, 4 Sep 2024 23:55:28 +0100 Message-Id: <20240904225530.3888315-4-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240904225530.3888315-1-andrew.cooper3@citrix.com> References: <20240904225530.3888315-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 ... and drop generic_hweight32(). As noted previously, the only two users of hweight32() are in __init paths. The int-optimised form of generic_hweight() is only two instructions shorter than the long-optimised form, and even then only on architectures which lack fast multiplication, so there's no point providing an int-optimised form. No functional change. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich Acked-by: Stefano Stabellini Acked-by: Shawn Anastasio --- CC: Jan Beulich CC: Roger Pau Monné CC: Stefano Stabellini CC: Julien Grall CC: Volodymyr Babchuk CC: Bertrand Marquis CC: Michal Orzel CC: Oleksii Kurochko CC: Shawn Anastasio v2: * Reorder with respect to the hweight64() patch * Rerwrite the commit message * s/__pure/attr_const/ --- xen/arch/arm/include/asm/bitops.h | 1 - xen/arch/ppc/include/asm/bitops.h | 1 - xen/arch/x86/include/asm/bitops.h | 1 - xen/include/xen/bitops.h | 5 +++++ 4 files changed, 5 insertions(+), 3 deletions(-) diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h index 91cd167b6bbb..b28c25b3d52d 100644 --- a/xen/arch/arm/include/asm/bitops.h +++ b/xen/arch/arm/include/asm/bitops.h @@ -85,7 +85,6 @@ bool clear_mask16_timeout(uint16_t mask, volatile void *p, * The Hamming Weight of a number is the total number of bits set in it. */ #define hweight64(x) generic_hweight64(x) -#define hweight32(x) generic_hweight32(x) #endif /* _ARM_BITOPS_H */ /* diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h index 64512e949530..f488a7c03425 100644 --- a/xen/arch/ppc/include/asm/bitops.h +++ b/xen/arch/ppc/include/asm/bitops.h @@ -133,6 +133,5 @@ static inline int test_and_set_bit(unsigned int nr, volatile void *addr) * The Hamming Weight of a number is the total number of bits set in it. */ #define hweight64(x) __builtin_popcountll(x) -#define hweight32(x) __builtin_popcount(x) #endif /* _ASM_PPC_BITOPS_H */ diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h index 4c5b21907a64..507b043b8a86 100644 --- a/xen/arch/x86/include/asm/bitops.h +++ b/xen/arch/x86/include/asm/bitops.h @@ -482,6 +482,5 @@ static always_inline unsigned int arch_flsl(unsigned long x) * The Hamming Weight of a number is the total number of bits set in it. */ #define hweight64(x) generic_hweight64(x) -#define hweight32(x) generic_hweight32(x) #endif /* _X86_BITOPS_H */ diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index 58c600155f7e..a462c3065158 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -326,6 +326,11 @@ static always_inline attr_const unsigned int hweightl(unsigned long x) #endif } +static always_inline attr_const unsigned int hweight32(uint32_t x) +{ + return hweightl(x); +} + /* --------------------- Please tidy below here --------------------- */ #ifndef find_next_bit From patchwork Wed Sep 4 22:55:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Andrew Cooper X-Patchwork-Id: 13791479 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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 14013CD4F4A for ; Wed, 4 Sep 2024 22:55:50 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.790822.1200629 (Exim 4.92) (envelope-from ) id 1slyue-0002TG-Au; Wed, 04 Sep 2024 22:55:44 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 790822.1200629; 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Wed, 04 Sep 2024 15:55:38 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: cf0d46d4-6b10-11ef-99a1-01e77a169b0f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1725490540; x=1726095340; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=hd3H+h3D3FJFoKSFWHnu0JXTNonfMBRV1dP4GfZ7wVk=; b=f1GZ1qryOrE+AIVt8dIDF4Cwv3AXhIjWhsBr2FZ561KeXFI2cyQ5OYkz7p9o8UNzMo cSIPYwox1axo0XiPOgXsPIh/NI4o1cNiea8uSBj0JYqlRKUeTS82AITox5PyB06baato BWJ2NuFDzaKUVOxkJ7WegpgkwEIKaPbUBUQ7M= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1725490540; x=1726095340; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; 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This is identical on all architectures except ARM32. Add one extra SELF_TEST to check that hweight64() works when the input is split in half. No functional change. Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich Acked-by: Stefano Stabellini --- CC: Jan Beulich CC: Roger Pau Monné CC: Stefano Stabellini CC: Julien Grall CC: Volodymyr Babchuk CC: Bertrand Marquis CC: Michal Orzel CC: Oleksii Kurochko CC: Shawn Anastasio v3: * Use >=, even if it does differ from ffs() v2: * Reorder with respect to the hweight32() patch * s/__pure/attr_const/ --- xen/arch/arm/include/asm/bitops.h | 8 ------ xen/arch/ppc/include/asm/bitops.h | 8 ------ xen/arch/x86/include/asm/bitops.h | 8 ------ xen/common/bitops.c | 3 +++ xen/include/xen/bitops.h | 45 ++++++------------------------- 5 files changed, 11 insertions(+), 61 deletions(-) diff --git a/xen/arch/arm/include/asm/bitops.h b/xen/arch/arm/include/asm/bitops.h index b28c25b3d52d..f163d9bb4578 100644 --- a/xen/arch/arm/include/asm/bitops.h +++ b/xen/arch/arm/include/asm/bitops.h @@ -78,14 +78,6 @@ bool clear_mask16_timeout(uint16_t mask, volatile void *p, #define arch_fls(x) ((x) ? 32 - __builtin_clz(x) : 0) #define arch_flsl(x) ((x) ? BITS_PER_LONG - __builtin_clzl(x) : 0) -/** - * hweightN - returns the hamming weight of a N-bit word - * @x: the word to weigh - * - * The Hamming Weight of a number is the total number of bits set in it. - */ -#define hweight64(x) generic_hweight64(x) - #endif /* _ARM_BITOPS_H */ /* * Local variables: diff --git a/xen/arch/ppc/include/asm/bitops.h b/xen/arch/ppc/include/asm/bitops.h index f488a7c03425..c942e9432e20 100644 --- a/xen/arch/ppc/include/asm/bitops.h +++ b/xen/arch/ppc/include/asm/bitops.h @@ -126,12 +126,4 @@ static inline int test_and_set_bit(unsigned int nr, volatile void *addr) #define arch_hweightl(x) __builtin_popcountl(x) -/** - * hweightN - returns the hamming weight of a N-bit word - * @x: the word to weigh - * - * The Hamming Weight of a number is the total number of bits set in it. - */ -#define hweight64(x) __builtin_popcountll(x) - #endif /* _ASM_PPC_BITOPS_H */ diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h index 507b043b8a86..642d8e58b288 100644 --- a/xen/arch/x86/include/asm/bitops.h +++ b/xen/arch/x86/include/asm/bitops.h @@ -475,12 +475,4 @@ static always_inline unsigned int arch_flsl(unsigned long x) } #define arch_flsl arch_flsl -/** - * hweightN - returns the hamming weight of a N-bit word - * @x: the word to weigh - * - * The Hamming Weight of a number is the total number of bits set in it. - */ -#define hweight64(x) generic_hweight64(x) - #endif /* _X86_BITOPS_H */ diff --git a/xen/common/bitops.c b/xen/common/bitops.c index 5e5d20d225d7..91ae961440af 100644 --- a/xen/common/bitops.c +++ b/xen/common/bitops.c @@ -144,6 +144,9 @@ static void __init test_hweight(void) CHECK(hweightl, 1 | (1UL << (BITS_PER_LONG - 1)), 2); CHECK(hweightl, -1UL, BITS_PER_LONG); + + /* unsigned int hweight64(uint64_t) */ + CHECK(hweight64, -1ULL, 64); } static void __init __constructor test_bitops(void) diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h index a462c3065158..12eb88fb1255 100644 --- a/xen/include/xen/bitops.h +++ b/xen/include/xen/bitops.h @@ -331,6 +331,14 @@ static always_inline attr_const unsigned int hweight32(uint32_t x) return hweightl(x); } +static always_inline attr_const unsigned int hweight64(uint64_t x) +{ + if ( BITS_PER_LONG >= 64 ) + return hweightl(x); + else + return hweight32(x >> 32) + hweight32(x); +} + /* --------------------- Please tidy below here --------------------- */ #ifndef find_next_bit @@ -399,43 +407,6 @@ static inline int get_count_order(unsigned int count) return order; } -/* - * hweightN: returns the hamming weight (i.e. the number - * of bits set) of a N-bit word - */ - -static inline unsigned int generic_hweight32(unsigned int w) -{ - w -= (w >> 1) & 0x55555555; 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Wed, 04 Sep 2024 15:55:40 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Jan Beulich , =?utf-8?q?Roger_Pau_Monn=C3=A9?= Subject: [PATCH v3 5/5] x86/bitops: Use the POPCNT instruction when available Date: Wed, 4 Sep 2024 23:55:30 +0100 Message-Id: <20240904225530.3888315-6-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240904225530.3888315-1-andrew.cooper3@citrix.com> References: <20240904225530.3888315-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 It has existed in x86 CPUs since 2008, so we're only 16 years late adding support. With all the other scafolding in place, implement arch_hweightl() for x86. The only complication is that the call to arch_generic_hweightl() is behind the compilers back. Address this by writing it in ASM and ensure that it preserves all registers. Copy the code generation from generic_hweightl(). It's not a complicated algorithm, and is easy to regenerate if needs be, but cover it with the same unit tests as test_generic_hweightl() just for piece of mind. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich --- CC: Jan Beulich CC: Roger Pau Monné v3: * Reinstate dropped CONFIG_SELF_TESTS * Leave grep fodder for CODE_FILL until we can find a nicer way of doing this. v2: * Fix MISRA 8.2 (parameter name) and 8.5 (single declaration) regressions. * Rename {arch->x86}-generic-hweightl.{S->c} * Adjust ASM formating --- xen/arch/x86/include/asm/bitops.h | 23 ++++++++++ xen/lib/Makefile | 1 + xen/lib/x86-generic-hweightl.c | 71 +++++++++++++++++++++++++++++++ 3 files changed, 95 insertions(+) create mode 100644 xen/lib/x86-generic-hweightl.c diff --git a/xen/arch/x86/include/asm/bitops.h b/xen/arch/x86/include/asm/bitops.h index 642d8e58b288..39e37f1cbe55 100644 --- a/xen/arch/x86/include/asm/bitops.h +++ b/xen/arch/x86/include/asm/bitops.h @@ -6,6 +6,7 @@ */ #include +#include #include /* @@ -475,4 +476,26 @@ static always_inline unsigned int arch_flsl(unsigned long x) } #define arch_flsl arch_flsl +unsigned int arch_generic_hweightl(unsigned long x); + +static always_inline unsigned int arch_hweightl(unsigned long x) +{ + unsigned int r; + + /* + * arch_generic_hweightl() is written in ASM in order to preserve all + * registers, as the compiler can't see the call. + * + * This limits the POPCNT instruction to using the same ABI as a function + * call (input in %rdi, output in %eax) but that's fine. + */ + alternative_io("call arch_generic_hweightl", + "popcnt %[val], %q[res]", X86_FEATURE_POPCNT, + ASM_OUTPUT2([res] "=a" (r) ASM_CALL_CONSTRAINT), + [val] "D" (x)); + + return r; +} +#define arch_hweightl arch_hweightl + #endif /* _X86_BITOPS_H */ diff --git a/xen/lib/Makefile b/xen/lib/Makefile index b6558e108bd9..54440f628aae 100644 --- a/xen/lib/Makefile +++ b/xen/lib/Makefile @@ -36,6 +36,7 @@ lib-y += strtol.o lib-y += strtoll.o lib-y += strtoul.o lib-y += strtoull.o +lib-$(CONFIG_X86) += x86-generic-hweightl.o lib-$(CONFIG_X86) += xxhash32.o lib-$(CONFIG_X86) += xxhash64.o diff --git a/xen/lib/x86-generic-hweightl.c b/xen/lib/x86-generic-hweightl.c new file mode 100644 index 000000000000..123a5b43928d --- /dev/null +++ b/xen/lib/x86-generic-hweightl.c @@ -0,0 +1,71 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include +#include +#include + +/* + * An implementation of generic_hweightl() used on hardware without the POPCNT + * instruction. + * + * This function is called from within an ALTERNATIVE in arch_hweightl(). + * i.e. behind the back of the compiler. Therefore all registers are callee + * preserved. + * + * The ASM is what GCC-12 emits for generic_hweightl() in a release build of + * Xen, with spilling of %rdi/%rdx to preserve the callers registers. + * + * Note: When we can use __attribute__((no_caller_saved_registers)) + * unconditionally (GCC 7, Clang 5), we can implement this in plain C. + */ +asm ( + ".type arch_generic_hweightl, STT_FUNC\n\t" + ".globl arch_generic_hweightl\n\t" + ".hidden arch_generic_hweightl\n\t" + ".balign " STR(CONFIG_FUNCTION_ALIGNMENT) ", 0x90\n" /* CODE_FILL */ + "arch_generic_hweightl:\n\t" + + "push %rdi\n\t" + "push %rdx\n\t" + + "movabs $0x5555555555555555, %rdx\n\t" + "mov %rdi, %rax\n\t" + "shr $1, %rax\n\t" + "and %rdx, %rax\n\t" + "sub %rax, %rdi\n\t" + "movabs $0x3333333333333333, %rax\n\t" + "mov %rdi, %rdx\n\t" + "shr $2, %rdi\n\t" + "and %rax, %rdx\n\t" + "and %rax, %rdi\n\t" + "add %rdi, %rdx\n\t" + "mov %rdx, %rax\n\t" + "shr $4, %rax\n\t" + "add %rdx, %rax\n\t" + "movabs $0x0f0f0f0f0f0f0f0f, %rdx\n\t" + "and %rdx, %rax\n\t" + "movabs $0x0101010101010101, %rdx\n\t" + "imul %rdx, %rax\n\t" + "shr $" STR(BITS_PER_LONG) "- 8, %rax\n\t" + + "pop %rdx\n\t" + "pop %rdi\n\t" + + "ret\n\t" + + ".size arch_generic_hweightl, . - arch_generic_hweightl\n\t" +); + +#ifdef CONFIG_SELF_TESTS +static void __init __constructor test_arch_generic_hweightl(void) +{ + RUNTIME_CHECK(arch_generic_hweightl, 0, 0); + RUNTIME_CHECK(arch_generic_hweightl, 1, 1); + RUNTIME_CHECK(arch_generic_hweightl, 3, 2); + RUNTIME_CHECK(arch_generic_hweightl, 7, 3); + RUNTIME_CHECK(arch_generic_hweightl, 0xff, 8); + + RUNTIME_CHECK(arch_generic_hweightl, 1 | (1UL << (BITS_PER_LONG - 1)), 2); + RUNTIME_CHECK(arch_generic_hweightl, -1UL, BITS_PER_LONG); +} +#endif