From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from userp2120.oracle.com ([156.151.31.85]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWUdb-0007YQ-AW for kexec@lists.infradead.org; Thu, 07 May 2020 00:43:45 +0000 From: Anthony Yznaga Subject: [RFC 06/43] mm: PKRAM: implement byte stream operations Date: Wed, 6 May 2020 17:41:32 -0700 Message-Id: <1588812129-8596-7-git-send-email-anthony.yznaga@oracle.com> In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> References: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-doc@vger.kernel.org, gustavo@embeddedor.com, peterz@infradead.org, kexec@lists.infradead.org, paul.c.lai@intel.com, dave.hansen@linux.intel.com, mhocko@kernel.org, lei.l.li@intel.com, nivedita@alum.mit.edu, ziqian.lzq@antfin.com, hpa@zytor.com, ardb@kernel.org, ashok.raj@intel.com, bhe@redhat.com, corbet@lwn.net, masahiroy@kernel.org, rafael.j.wysocki@intel.com, hughd@google.com, willy@infradead.org, rppt@linux.ibm.com, mingo@redhat.com, vdavydov.dev@gmail.com, ying.huang@intel.com, Thomas.Lendacky@amd.com, kevin.tian@intel.com, jroedel@suse.de, keescook@chromium.org, dan.j.williams@intel.com, bp@alien8.de, zhiyuan.lv@intel.com, luto@kernel.org, tglx@linutronix.de, andriy.shevchenko@linux.intel.com, dima@golovin.in, yang.shi@linux.alibaba.com, ndesaulniers@google.com, zhenzhong.duan@oracle.com, guro@fb.com, minchan@kernel.org, ebiederm@xmission.com, jason.zeng@intel.com, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, daniel.kiper@oracle.com This patch adds the ability to save arbitrary byte streams up to a total length of one page to a PKRAM object using pkram_write() to be restored later using pkram_read(). Originally-by: Vladimir Davydov Signed-off-by: Anthony Yznaga --- include/linux/pkram.h | 4 +++ mm/pkram.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 86 insertions(+), 2 deletions(-) diff --git a/include/linux/pkram.h b/include/linux/pkram.h index 584cadb662b4..a58dd2ea835a 100644 --- a/include/linux/pkram.h +++ b/include/linux/pkram.h @@ -17,6 +17,10 @@ struct pkram_stream { unsigned int entry_idx; /* next entry in link */ unsigned long next_index; + + /* byte data */ + struct page *data_page; + unsigned int data_offset; }; #define PKRAM_NAME_MAX 256 /* including nul */ diff --git a/mm/pkram.c b/mm/pkram.c index 9164060e36f5..06b471eea0b0 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include #include +#include #include #include #include @@ -42,6 +43,8 @@ struct pkram_link { ((PAGE_SIZE-sizeof(struct pkram_link))/sizeof(pkram_entry_t)) struct pkram_obj { + __u64 data_pfn; /* points to the byte data */ + __u64 data_len; /* byte data size */ __u64 link_pfn; /* points to the first link of the object */ __u64 obj_pfn; /* points to the next object in the list */ }; @@ -407,6 +410,9 @@ void pkram_finish_load_obj(struct pkram_stream *ps) } } + if (ps->data_page) + pkram_free_page(page_address(ps->data_page)); + pkram_truncate_obj(obj); pkram_free_page(obj); } @@ -422,6 +428,9 @@ void pkram_finish_load(struct pkram_stream *ps) BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD); + if (ps->data_page) + put_page(ps->data_page); + pkram_truncate_node(node); pkram_free_page(node); } @@ -581,10 +590,41 @@ struct page *pkram_load_page(struct pkram_stream *ps, unsigned long *index, shor * * On success, returns the number of bytes written, which is always equal to * @count. On failure, -errno is returned. + * + * Error values: + * %ENOMEM: insufficient amount of memory available */ ssize_t pkram_write(struct pkram_stream *ps, const void *buf, size_t count) { - return -ENOSYS; + struct pkram_node *node = ps->node; + struct pkram_obj *obj = ps->obj; + void *addr; + + BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE); + + if (!ps->data_page) { + struct page *page; + + page = pkram_alloc_page((ps->gfp_mask & GFP_RECLAIM_MASK) | + __GFP_HIGHMEM | __GFP_ZERO); + if (!page) + return -ENOMEM; + + ps->data_page = page; + ps->data_offset = 0; + obj->data_pfn = page_to_pfn(page); + } + + BUG_ON(count > PAGE_SIZE - ps->data_offset); + + addr = kmap_atomic(ps->data_page); + memcpy(addr + ps->data_offset, buf, count); + kunmap_atomic(addr); + + obj->data_len += count; + ps->data_offset += count; + + return count; } /** @@ -597,5 +637,45 @@ ssize_t pkram_write(struct pkram_stream *ps, const void *buf, size_t count) */ size_t pkram_read(struct pkram_stream *ps, void *buf, size_t count) { - return 0; + struct pkram_node *node = ps->node; + struct pkram_obj *obj = ps->obj; + size_t copy_count; + char *addr; + + BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD); + + if (!count || !obj->data_len) + return 0; + + if (!ps->data_page) { + struct page *page; + + page = pfn_to_page(obj->data_pfn); + if (!page) + return 0; + + ps->data_page = page; + ps->data_offset = 0; + obj->data_pfn = 0; + } + + BUG_ON(count > PAGE_SIZE - ps->data_offset); + + copy_count = min_t(size_t, count, PAGE_SIZE - ps->data_offset); + if (copy_count > obj->data_len) + copy_count = obj->data_len; + + addr = kmap_atomic(ps->data_page); + memcpy(buf, addr + ps->data_offset, copy_count); + kunmap_atomic(addr); + + obj->data_len -= copy_count; + ps->data_offset += copy_count; + + if (!obj->data_len) { + pkram_free_page(page_address(ps->data_page)); + ps->data_page = NULL; + } + + return copy_count; } -- 2.13.3 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec