From nobody Tue Feb 10 21:41:17 2026 Received: from cstnet.cn (smtp81.cstnet.cn [159.226.251.81]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F35C529ACC3 for ; Mon, 20 Oct 2025 09:10:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.81 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760951419; cv=none; b=dW5iF3vabOWa1fW+/scY3rh5mnomobc2Z+eGQoSzWiz6gxtiT63bt1HNKoCI0fGba5g+5rvEdzaSF3OBQ9RXsR/vh7UpXvXeh+yP/CGDIvCb0XbnGlxjy/6Acamk9nHeK0iIxUqxAo1W5t+DeXJ2FJpuDCtOEYFbOX7RO0SRwlk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760951419; c=relaxed/simple; bh=1Fpu5TRjaKm/gCFWSwIXaUyUaS0kUs+SPCDS31PS0kk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=b/FpPdksjhsaGeoQG2ECco0v9FHHCtp09gBj58mPVFOcNTHV8e+75UFeGq+zqLVcsVXtAPUrKj35p/PSE0SeDuop62lorDfR97pPuSd/SqfjuqWafC1mHalSRF03i2KrwdtMd+wDZF3rEVOoE1hcb7L1U0g0L0Tz6AuEHBY0zrs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from [127.0.0.2] (unknown [114.241.85.109]) by APP-03 (Coremail) with SMTP id rQCowAD3RoFo_PVo4mflEQ--.23190S3; Mon, 20 Oct 2025 17:10:00 +0800 (CST) From: Vivian Wang Date: Mon, 20 Oct 2025 17:09:56 +0800 Subject: [PATCH v4 1/5] riscv: pgtable: Use riscv_has_extension_unlikely Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251020-riscv-altn-helper-wip-v4-1-ef941c87669a@iscas.ac.cn> References: <20251020-riscv-altn-helper-wip-v4-0-ef941c87669a@iscas.ac.cn> In-Reply-To: <20251020-riscv-altn-helper-wip-v4-0-ef941c87669a@iscas.ac.cn> To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Yury Norov , Rasmus Villemoes , Paul Walmsley Cc: Charlie Jenkins , Xiao Wang , =?utf-8?q?Christoph_M=C3=BCllner?= , Vivian Wang , Vivian Wang , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org X-Mailer: b4 0.14.3 X-CM-TRANSID: rQCowAD3RoFo_PVo4mflEQ--.23190S3 X-Coremail-Antispam: 1UD129KBjvJXoWxJFWUAw18GrW7Aw4xtr1DJrb_yoW5Zr4Upr Z3Ca9IgrWrCw1Ivrs7trs8ur4Yv393W3W3Kr1Sg3WFyr4ak3y2vrsxJa1Syry8JFWxX348 KF4fKr4UG3Wayr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUm014x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_Jr4l82xGYIkIc2 x26xkF7I0E14v26r4j6ryUM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2z4x0 Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Cr0_Gr1UM2 8EF7xvwVC2z280aVAFwI0_Cr1j6rxdM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq3wAS 0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2 IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0 Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kIc2 xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWU JVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67 kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCwCI42IY 6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0x vEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVj vjDU0xZFpf9x0JUfKs8UUUUU= X-CM-SenderInfo: pzdqw2pxlnt03j6l2u1dvotugofq/ Use riscv_has_extension_unlikely() to check for RISCV_ISA_EXT_SVVPTC, replacing the use of asm goto with ALTERNATIVE. The "unlikely" variant is used to match the behavior of the original implementation using ALTERNATIVE("nop", "j %l[svvptc]", ...). Note that this makes the check for RISCV_ISA_EXT_SVVPTC a runtime one if RISCV_ALTERNATIVE=3Dn, but it should still be worthwhile to do so given that TLB flushes are relatively slow. Signed-off-by: Vivian Wang --- arch/riscv/include/asm/pgtable.h | 15 +++++++-------- arch/riscv/mm/pgtable.c | 22 ++++++++++------------ 2 files changed, 17 insertions(+), 20 deletions(-) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgta= ble.h index 29e994a9afb6..d1a4bdc36f2c 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -496,8 +496,13 @@ static inline void update_mmu_cache_range(struct vm_fa= ult *vmf, struct vm_area_struct *vma, unsigned long address, pte_t *ptep, unsigned int nr) { - asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1) - : : : : svvptc); + /* + * Svvptc guarantees that the new valid pte will be visible within + * a bounded timeframe, so when the uarch does not cache invalid + * entries, we don't have to do anything. + */ + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SVVPTC)) + return; =20 /* * The kernel assumes that TLBs don't cache invalid entries, but @@ -509,12 +514,6 @@ static inline void update_mmu_cache_range(struct vm_fa= ult *vmf, while (nr--) local_flush_tlb_page(address + nr * PAGE_SIZE); =20 -svvptc:; - /* - * Svvptc guarantees that the new valid pte will be visible within - * a bounded timeframe, so when the uarch does not cache invalid - * entries, we don't have to do anything. - */ } #define update_mmu_cache(vma, addr, ptep) \ update_mmu_cache_range(NULL, vma, addr, ptep, 1) diff --git a/arch/riscv/mm/pgtable.c b/arch/riscv/mm/pgtable.c index 8b6c0a112a8d..807c0a0de182 100644 --- a/arch/riscv/mm/pgtable.c +++ b/arch/riscv/mm/pgtable.c @@ -9,8 +9,16 @@ int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address, pte_t *ptep, pte_t entry, int dirty) { - asm goto(ALTERNATIVE("nop", "j %l[svvptc]", 0, RISCV_ISA_EXT_SVVPTC, 1) - : : : : svvptc); + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SVVPTC)) { + if (!pte_same(ptep_get(ptep), entry)) { + __set_pte_at(vma->vm_mm, ptep, entry); + /* Here only not svadu is impacted */ + flush_tlb_page(vma, address); + return true; + } + + return false; + } =20 if (!pte_same(ptep_get(ptep), entry)) __set_pte_at(vma->vm_mm, ptep, entry); @@ -19,16 +27,6 @@ int ptep_set_access_flags(struct vm_area_struct *vma, * the case that the PTE changed and the spurious fault case. */ return true; - -svvptc: - if (!pte_same(ptep_get(ptep), entry)) { - __set_pte_at(vma->vm_mm, ptep, entry); - /* Here only not svadu is impacted */ - flush_tlb_page(vma, address); - return true; - } - - return false; } =20 int ptep_test_and_clear_young(struct vm_area_struct *vma, --=20 2.51.0