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Sun, 08 Nov 2026 14:36:02 -0800 (PST) Received: from buildhost.darklands.se ([2001:9b1:ff:d701:51eb:176f:63d9:53f8]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6b721ebc7b0sm859272a12.14.2026.11.08.14.36.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Nov 2026 14:36:01 -0800 (PST) From: Magnus Lindholm To: davem@davemloft.net, andreas@gaisler.com Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linmag7@gmail.com Subject: [PATCH 5/9] sparc32: preset modified and referenced bits in kmap PTEs Date: Sun, 8 Nov 2026 23:34:15 +0100 Message-ID: <20261108223516.1125534-6-linmag7@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261108223516.1125534-1-linmag7@gmail.com> References: <20261108223516.1125534-1-linmag7@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Preset SRMMU_DIRTY and SRMMU_REF in kernel kmap PTEs, matching PAGE_KERNEL. These mappings do not use hardware M/R transitions for user dirty/accessed accounting. The protection applies to persistent PKMAP entries as well as transient local mappings. ROSS SPARC RISC User's Guide, section 4.2.1.1, describes hardware table walks and PTE updates when a write or translating operation encounters an unset M/R bit. Presetting the bits avoids those updates for kernel accesses. A whole-context cache flush does not perform that translating access. This also provides the PTE convention needed by subsequent alias reconciliation, but does not by itself provide that protocol. Signed-off-by: Magnus Lindholm --- arch/sparc/include/asm/highmem.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/sparc/include/asm/highmem.h b/arch/sparc/include/asm/highmem.h index 14b03f348823..d451232625d3 100644 --- a/arch/sparc/include/asm/highmem.h +++ b/arch/sparc/include/asm/highmem.h @@ -30,7 +30,12 @@ void sparc32_kmap_local_cache_flush(unsigned long vaddr); void sparc32_kmap_local_tlb_flush(unsigned long vaddr); void sparc32_kmap_local_post_map(unsigned long vaddr, pte_t pteval); -#define kmap_prot __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE) +/* + * Kernel kmap mappings do not need hardware dirty/accessed tracking. + * Match PAGE_KERNEL and avoid M/R updates during translated accesses. + */ +#define kmap_prot __pgprot(SRMMU_ET_PTE | SRMMU_PRIV | SRMMU_CACHE | \ + SRMMU_DIRTY | SRMMU_REF) extern pte_t *pkmap_page_table; /* -- 2.43.0