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Fri, 10 Mar 2023 02:02:23 GMT Received: from [10.253.32.183] (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.41; Thu, 9 Mar 2023 18:02:19 -0800 Message-ID: Date: Fri, 10 Mar 2023 10:02:17 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.6.1 Subject: Re: [PATCH v2] mm,kfence: decouple kfence from page granularity mapping judgement Content-Language: en-US To: Marco Elver CC: , , , , , , , , , , , , , , References: <1678376273-7030-1-git-send-email-quic_zhenhuah@quicinc.com> From: Zhenhua Huang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: _V3dJwdVVIZQ07JTf682-QZDx6L3FnkA X-Proofpoint-GUID: _V3dJwdVVIZQ07JTf682-QZDx6L3FnkA X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-09_14,2023-03-09_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 malwarescore=0 priorityscore=1501 suspectscore=0 spamscore=0 clxscore=1015 impostorscore=0 mlxscore=0 mlxlogscore=985 phishscore=0 lowpriorityscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303100011 X-Rspamd-Queue-Id: 68760C000E X-Stat-Signature: 756ispd7z6rrfp58o4zs6nke1z9r46at X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1678413754-903708 X-HE-Meta: U2FsdGVkX18chOuLDTBadK73LFlPU1TwCkOGGVC8Lvzsl7S0OgQMhrUVcq/FSDnUlP52ZqDIiNSW2SOzGfZUwaBuHTS7vIEuvDooEGkocCBKv0cz88ZyC4tP87Zg6QggPfXF8DcDy2L4yjW339vbDc6z0fHR7En1kOBC6TvF9nsfedD4OPvCJWzOnnp4fvMwlWaL0BicJ6A6lwm113WgftxgZ+3aK4u5fSXUbWyeSQImObIcWvBeH89UUtTiZB4QBG/HhLoV+t3zDsMTULAGmKMrvhFuS6/sas0Tp5qoMj5pP6ojMMaNWBiRGNqIiRmBc0KucVmilKfpphXSGY1HzcPwcgXS0vKfRl2eZIP06KcXirJx4VzNWk5AOo+Le+qp8gzLeAOiWJ29f9bKfVdSp8FU5BGRJA5YnDAeKi66RrgHXCyav+98YgrInmYi+x5YYoxdfLvBTnH1lVmqTNfN2GF2Ou/fdBqJson4/OOD/cZel9WEcy+vW0xr0cgYC+Ihq2qytlPDLZhM19xDoLGV7Exf53hTgySNs05kVJeJF1JxCQJtuC/GybZna/OK8qztEh8hTFhpYU2s+I9hf8kQi+8iS9ZzKAI+M3I5eYcOYVfaCmu7UyTq7Ymetjxc+RHcHZGbONKQYlk+41p1SDuNg8014hCRHeWeN4WXCbAAyusM6UnZjEurID9z2/jO0l3HU/N4ER/PpTaEUmoUhOwFQciOXA359ZKO1U8wfj2dZnONqzLxULP5T5cQHoGyzo4o6CeNt56dxI5/cQ7qS8XnIneN4P83sO8DF8BYGp1FUOq8RK6c7ETsvgRsNdDQTLdRWieTAabnZCJx4Zmoegy3gWMYpNuOTf88jHgjTv8w98ceRKiSPxh5mIVjR1l287T2JM9tepasJVLwyXkH5HzlZqYgXW37x5/M/OAStL+MM88MwNyYd0VqpDX4fEoar5ZDXmwCCsJ5BcIfPSsNinm Uu7BYxmO JZi+DvWRyEkchK79FTXblyM5zHp8JouKacwumHLrRa/10xP99IitizVkqYOBX//gQxcgfrb8xHGpLuqZjCJON+eXZtuSfV0mfgkbUmtgdd/kEVGOOlbbk4G+dn6uM6Nq9apOEe8DQTV2e3+GCm5JiAKs5ldqQZ39FWJS5VimxP0qKTPWWybcp/N0LDTo61B6EqmIpNHE5URo7nMzPx1ipi4ZoHAqp2l1ErGkKpIrWVzmiISLuSoZWYyt+wnApLdAalRqv0SGZYQDDFh+TzK1IYrWD64kOJ0BgyfXw6wqfW/J3QPRkoNaCbPb08azgTFQ4pI+SV9/75Teojct/IK9ckatVz7CDHAF5PKQpncMu9hFoZXs75totsRrly3/uXuInbDEuBtQh8G3yYGSsLeht5O/pfQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Thanks Marco for your detailed review! On 2023/3/9 23:48, Marco Elver wrote: > On Thu, 9 Mar 2023 at 16:38, Zhenhua Huang wrote: >> >> Kfence only needs its pool to be mapped as page granularity, previous >> judgement was a bit over protected. Decouple it from judgement and do >> page granularity mapping for kfence pool only [1]. >> >> To implement this, also relocate the kfence pool allocation before the >> linear mapping setting up, arm64_kfence_alloc_pool is to allocate phys >> addr, __kfence_pool is to be set after linear mapping set up. >> >> LINK: [1] https://lore.kernel.org/linux-arm-kernel/1675750519-1064-1-git-send-email-quic_zhenhuah@quicinc.com/T/ >> Suggested-by: Mark Rutland >> Signed-off-by: Zhenhua Huang >> --- >> arch/arm64/mm/mmu.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ >> arch/arm64/mm/pageattr.c | 5 ++--- >> include/linux/kfence.h | 7 +++++++ >> mm/kfence/core.c | 9 +++++++++ >> 4 files changed, 62 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 6f9d889..46afe3f 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -24,6 +24,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -525,6 +526,33 @@ static int __init enable_crash_mem_map(char *arg) >> } >> early_param("crashkernel", enable_crash_mem_map); >> >> +#ifdef CONFIG_KFENCE >> + >> +static phys_addr_t arm64_kfence_alloc_pool(void) >> +{ >> + phys_addr_t kfence_pool = 0; >> + >> + if (!kfence_sample_interval) >> + return 0; >> + >> + kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); >> + if (!kfence_pool) { >> + pr_err("failed to allocate kfence pool\n"); >> + return 0; >> + } >> + >> + return kfence_pool; >> +} >> + >> +#else >> + >> +static phys_addr_t arm64_kfence_alloc_pool(void) >> +{ >> + return (phys_addr_t)NULL; > > Just return "0" - which the above function does as well on error. Or > the above function should also do (phys_addr_t)NULL for consistency. Done > >> +} >> + >> +#endif >> + >> static void __init map_mem(pgd_t *pgdp) >> { >> static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN); >> @@ -532,6 +560,7 @@ static void __init map_mem(pgd_t *pgdp) >> phys_addr_t kernel_end = __pa_symbol(__init_begin); >> phys_addr_t start, end; >> int flags = NO_EXEC_MAPPINGS; >> + phys_addr_t kfence_pool = 0; >> u64 i; >> >> /* >> @@ -564,6 +593,10 @@ static void __init map_mem(pgd_t *pgdp) >> } >> #endif >> >> + kfence_pool = arm64_kfence_alloc_pool(); >> + if (kfence_pool) >> + memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE); >> + >> /* map all the memory banks */ >> for_each_mem_range(i, &start, &end) { >> if (start >= end) >> @@ -608,6 +641,17 @@ static void __init map_mem(pgd_t *pgdp) >> } >> } >> #endif >> + >> + /* Kfence pool needs page-level mapping */ >> + if (kfence_pool) { >> + __map_memblock(pgdp, kfence_pool, >> + kfence_pool + KFENCE_POOL_SIZE, >> + pgprot_tagged(PAGE_KERNEL), >> + NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); >> + memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE); >> + /* kfence_pool really mapped now */ >> + kfence_set_pool(kfence_pool); >> + } >> } >> >> void mark_rodata_ro(void) >> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c >> index 79dd201..61156d0 100644 >> --- a/arch/arm64/mm/pageattr.c >> +++ b/arch/arm64/mm/pageattr.c >> @@ -22,12 +22,11 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED >> bool can_set_direct_map(void) >> { >> /* >> - * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be >> + * rodata_full and DEBUG_PAGEALLOC require linear map to be >> * mapped at page granularity, so that it is possible to >> * protect/unprotect single pages. >> */ >> - return (rodata_enabled && rodata_full) || debug_pagealloc_enabled() || >> - IS_ENABLED(CONFIG_KFENCE); >> + return (rodata_enabled && rodata_full) || debug_pagealloc_enabled(); >> } >> >> static int change_page_range(pte_t *ptep, unsigned long addr, void *data) >> diff --git a/include/linux/kfence.h b/include/linux/kfence.h >> index 726857a..d982ac2 100644 >> --- a/include/linux/kfence.h >> +++ b/include/linux/kfence.h >> @@ -64,6 +64,11 @@ static __always_inline bool is_kfence_address(const void *addr) >> void __init kfence_alloc_pool(void); >> >> /** >> + * kfence_set_pool() - KFENCE pool mapped and can be used > > I don't understand the comment. Maybe just "allows an arch to set the > KFENCE pool during early init" What I want to emphasize is __kfence_pool can be used now :) Sure, your comment is more clear. > >> + */ >> +void __init kfence_set_pool(phys_addr_t addr); >> + >> +/** >> * kfence_init() - perform KFENCE initialization at boot time >> * >> * Requires that kfence_alloc_pool() was called before. This sets up the >> @@ -222,8 +227,10 @@ bool __kfence_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *sla >> >> #else /* CONFIG_KFENCE */ >> >> +#define KFENCE_POOL_SIZE 0 >> static inline bool is_kfence_address(const void *addr) { return false; } >> static inline void kfence_alloc_pool(void) { } >> +static inline void kfence_set_pool(phys_addr_t addr) { } >> static inline void kfence_init(void) { } >> static inline void kfence_shutdown_cache(struct kmem_cache *s) { } >> static inline void *kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) { return NULL; } >> diff --git a/mm/kfence/core.c b/mm/kfence/core.c >> index 5349c37..a17c20c2 100644 >> --- a/mm/kfence/core.c >> +++ b/mm/kfence/core.c >> @@ -814,12 +814,21 @@ void __init kfence_alloc_pool(void) >> if (!kfence_sample_interval) >> return; >> >> + /* if __kfence_pool already initialized in some arch, abort */ > > Abort sounds like it's a failure condition, but it's actually ok. > > Maybe just write: > > /* Check if the pool has already been initialized by arch; if so, > skip the below. */ Yes, your comment is more clear. Done. > >> + if (__kfence_pool) >> + return; >> + >> __kfence_pool = memblock_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); >> >> if (!__kfence_pool) >> pr_err("failed to allocate pool\n"); >> } >> >> +void __init kfence_set_pool(phys_addr_t addr) >> +{ >> + __kfence_pool = phys_to_virt(addr); >> +} >> + > > The rest looks good. Updated patchset V 3 :)