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Fri, 17 Jul 2026 09:24:16 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 17 Jul 2026 09:24:16 +0000 (GMT) From: Heiko Carstens To: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand Cc: linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 4/4] s390: Add support for DCACHE_WORD_ACCESS (again) Date: Fri, 17 Jul 2026 11:24:15 +0200 Message-ID: <20260717092415.3039699-5-hca@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260717092415.3039699-1-hca@linux.ibm.com> References: <20260717092415.3039699-1-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: JuGxmwsCVxTqi3RNl1UB94jyQ1Q4sIc7 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzE3MDA5MSBTYWx0ZWRfX2bWyISBEuxSH u4rEVSpXXiLek4jFtMuod6errOCThn4w7A7bp3BpnXsOYY7aSAXu/oPjhdcnQMviX84QcUjBVcc j0u6ByEGtH2kbIoTRh4EMwfEWWEDRHQ= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzE3MDA5MSBTYWx0ZWRfX3GSz+8mFGHxK 1hg0QNaOAT53iitDKle4aLSfLOGmsR59MQyP+8HHtMnkFKB1BLMTTB42way2Yf+bJCAghpCVgJT 8gseOJLBEj5sxsrH01ZACV1TPQtiR1UPLms0FZmCI0zvM2yJj4a0p4adxKKvdaqO5j+IteZ2RYo MYoUKMMXrH9GFhVntFm0qKCGY5RGMr1472fmqpKqLau7Hmkcf+J0EIQ4jjmPA81c0JANGfh9bh6 nyOtDyxg7JHc5SSYp7WHZIk672CevZKlGDxagzsnygnHL56gFEoY2OgPOBIWotPEtZsDJpYJY9E c4i867TZ6ZiqFIg4irvmxvJJQHO0Z4N4D0WqjN8P3InXx+DwoqZc+7KfEiilGdXHCZlFJZFEBDa KR7uSf13F+EE0Uw39pSfMroBiosISZPChlT4wW5MyURi0A4lwO1ez6TkNKzoN8msIFdFDyt6ycY BQdXOhS2JZ+oZHTN7sg== X-Authority-Analysis: v=2.4 cv=IqMutr/g c=1 sm=1 tr=0 ts=6a59f4c6 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=iX4AGcIGDbhQ4BFKoYkA:9 X-Proofpoint-GUID: JuGxmwsCVxTqi3RNl1UB94jyQ1Q4sIc7 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-17_02,2026-07-15_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 impostorscore=0 malwarescore=0 adultscore=0 phishscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607170091 Implement load_unaligned_zeropad() and enable DCACHE_WORD_ACCESS to speed up string operations in fs/dcache.c and fs/namei.c. With the secure storage access exception cases addressed, add support for DCACHE_WORD_ACCESS again. Signed-off-by: Heiko Carstens --- arch/s390/Kconfig | 1 + arch/s390/include/asm/asm-extable.h | 4 ++++ arch/s390/include/asm/word-at-a-time.h | 22 ++++++++++++++++++++++ arch/s390/mm/extable.c | 18 ++++++++++++++++++ 4 files changed, 45 insertions(+) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 84404e6778d5..fe81c539ef2f 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -163,6 +163,7 @@ config S390 select ARCH_WANTS_THP_SWAP select BUILDTIME_TABLE_SORT select CLONE_BACKWARDS2 + select DCACHE_WORD_ACCESS if !KMSAN select DYNAMIC_FTRACE if FUNCTION_TRACER select FUNCTION_ALIGNMENT_8B if CC_IS_GCC select FUNCTION_ALIGNMENT_16B if !CC_IS_GCC diff --git a/arch/s390/include/asm/asm-extable.h b/arch/s390/include/asm/asm-extable.h index 99748c20e767..d23ea0c94e4e 100644 --- a/arch/s390/include/asm/asm-extable.h +++ b/arch/s390/include/asm/asm-extable.h @@ -12,6 +12,7 @@ #define EX_TYPE_UA_FAULT 3 #define EX_TYPE_UA_LOAD_REG 5 #define EX_TYPE_UA_LOAD_REGPAIR 6 +#define EX_TYPE_ZEROPAD 7 #define EX_TYPE_FPC 8 #define EX_TYPE_UA_MVCOS_TO 9 #define EX_TYPE_UA_MVCOS_FROM 10 @@ -79,6 +80,9 @@ #define EX_TABLE_UA_LOAD_REGPAIR(_fault, _target, _regerr, _regzero) \ __EX_TABLE(__ex_table, _fault, _target, EX_TYPE_UA_LOAD_REGPAIR, _regerr, _regzero, 0) +#define EX_TABLE_ZEROPAD(_fault, _target, _regdata, _regaddr) \ + __EX_TABLE(__ex_table, _fault, _target, EX_TYPE_ZEROPAD, _regdata, _regaddr, 0) + #define EX_TABLE_FPC(_fault, _target) \ __EX_TABLE(__ex_table, _fault, _target, EX_TYPE_FPC, __stringify(%%r0), __stringify(%%r0), 0) diff --git a/arch/s390/include/asm/word-at-a-time.h b/arch/s390/include/asm/word-at-a-time.h index e9287036392d..eaa19dee7699 100644 --- a/arch/s390/include/asm/word-at-a-time.h +++ b/arch/s390/include/asm/word-at-a-time.h @@ -4,6 +4,7 @@ #include #include +#include #include struct word_at_a_time { @@ -40,4 +41,25 @@ static inline unsigned long zero_bytemask(unsigned long data) return ~1UL << data; } +/* + * Load an unaligned word from kernel space. + * + * In the (very unlikely) case of the word being a page-crosser + * and the next page not being mapped, take the exception and + * return zeroes in the non-existing part. + */ +static inline unsigned long load_unaligned_zeropad(const void *addr) +{ + unsigned long data; + + asm_inline volatile( + "0: lg %[data],0(%[addr])\n" + "1: nopr %%r7\n" + EX_TABLE_ZEROPAD(0b, 1b, %[data], %[addr]) + EX_TABLE_ZEROPAD(1b, 1b, %[data], %[addr]) + : [data] "=d" (data) + : [addr] "a" (addr), "m" (*(unsigned long *)addr)); + return data; +} + #endif /* _ASM_WORD_AT_A_TIME_H */ diff --git a/arch/s390/mm/extable.c b/arch/s390/mm/extable.c index 063b4346742d..7498e858c401 100644 --- a/arch/s390/mm/extable.c +++ b/arch/s390/mm/extable.c @@ -50,6 +50,22 @@ static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex, return true; } +static bool ex_handler_zeropad(const struct exception_table_entry *ex, struct pt_regs *regs) +{ + unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data); + unsigned int reg_data = FIELD_GET(EX_DATA_REG_ERR, ex->data); + unsigned long data, addr, offset; + + addr = regs->gprs[reg_addr]; + offset = addr & (sizeof(unsigned long) - 1); + addr &= ~(sizeof(unsigned long) - 1); + data = *(unsigned long *)addr; + data <<= BITS_PER_BYTE * offset; + regs->gprs[reg_data] = data; + regs->psw.addr = extable_fixup(ex); + return true; +} + static bool ex_handler_fpc(const struct exception_table_entry *ex, struct pt_regs *regs) { fpu_sfpc(0); @@ -118,6 +134,8 @@ bool fixup_exception(struct pt_regs *regs) return ex_handler_ua_load_reg(ex, false, regs); case EX_TYPE_UA_LOAD_REGPAIR: return ex_handler_ua_load_reg(ex, true, regs); + case EX_TYPE_ZEROPAD: + return ex_handler_zeropad(ex, regs); case EX_TYPE_FPC: return ex_handler_fpc(ex, regs); case EX_TYPE_UA_MVCOS_TO: -- 2.53.0