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[86.146.209.214]) by smtp.googlemail.com with ESMTPSA id a8-20020a056000100800b002d8566128e5sm3744575wrx.25.2023.03.21.13.54.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 13:54:39 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton Cc: Baoquan He , Uladzislau Rezki , Matthew Wilcox , David Hildenbrand , Liu Shixin , Jiri Olsa , Jens Axboe , Alexander Viro , Lorenzo Stoakes Subject: [PATCH v4 2/4] fs/proc/kcore: convert read_kcore() to read_kcore_iter() Date: Tue, 21 Mar 2023 20:54:31 +0000 Message-Id: X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 82359140005 X-Stat-Signature: qu9at8jnhux1msd11kqmoxgxnoh373ws X-HE-Tag: 1679432082-182786 X-HE-Meta: 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 fGMrFUeT 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 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: Now we have eliminated spinlocks from the vread() case, convert read_kcore() to read_kcore_iter(). For the time being we still use a bounce buffer for vread(), however in the next patch we will convert this to interact directly with the iterator and eliminate the bounce buffer altogether. Signed-off-by: Lorenzo Stoakes Reviewed-by: David Hildenbrand --- fs/proc/kcore.c | 58 ++++++++++++++++++++++++------------------------- 1 file changed, 29 insertions(+), 29 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 556f310d6aa4..25e0eeb8d498 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -24,7 +24,7 @@ #include #include #include -#include +#include #include #include #include @@ -308,9 +308,12 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, } static ssize_t -read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) +read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { + struct file *file = iocb->ki_filp; char *buf = file->private_data; + loff_t *ppos = &iocb->ki_pos; + size_t phdrs_offset, notes_offset, data_offset; size_t page_offline_frozen = 1; size_t phdrs_len, notes_len; @@ -318,6 +321,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) size_t tsz; int nphdr; unsigned long start; + size_t buflen = iov_iter_count(iter); size_t orig_buflen = buflen; int ret = 0; @@ -333,7 +337,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) notes_offset = phdrs_offset + phdrs_len; /* ELF file header. */ - if (buflen && *fpos < sizeof(struct elfhdr)) { + if (buflen && *ppos < sizeof(struct elfhdr)) { struct elfhdr ehdr = { .e_ident = { [EI_MAG0] = ELFMAG0, @@ -355,19 +359,18 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) .e_phnum = nphdr, }; - tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); - if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { + tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *ppos); + if (copy_to_iter((char *)&ehdr + *ppos, tsz, iter) != tsz) { ret = -EFAULT; goto out; } - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* ELF program headers. */ - if (buflen && *fpos < phdrs_offset + phdrs_len) { + if (buflen && *ppos < phdrs_offset + phdrs_len) { struct elf_phdr *phdrs, *phdr; phdrs = kzalloc(phdrs_len, GFP_KERNEL); @@ -397,22 +400,21 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) phdr++; } - tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); - if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, - tsz)) { + tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *ppos); + if (copy_to_iter((char *)phdrs + *ppos - phdrs_offset, tsz, + iter) != tsz) { kfree(phdrs); ret = -EFAULT; goto out; } kfree(phdrs); - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* ELF note segment. */ - if (buflen && *fpos < notes_offset + notes_len) { + if (buflen && *ppos < notes_offset + notes_len) { struct elf_prstatus prstatus = {}; struct elf_prpsinfo prpsinfo = { .pr_sname = 'R', @@ -447,24 +449,23 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) vmcoreinfo_data, min(vmcoreinfo_size, notes_len - i)); - tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); - if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { + tsz = min_t(size_t, buflen, notes_offset + notes_len - *ppos); + if (copy_to_iter(notes + *ppos - notes_offset, tsz, iter) != tsz) { kfree(notes); ret = -EFAULT; goto out; } kfree(notes); - buffer += tsz; buflen -= tsz; - *fpos += tsz; + *ppos += tsz; } /* * Check to see if our file offset matches with any of * the addresses in the elf_phdr on our list. */ - start = kc_offset_to_vaddr(*fpos - data_offset); + start = kc_offset_to_vaddr(*ppos - data_offset); if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; @@ -497,7 +498,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) } if (!m) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -508,14 +509,14 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMALLOC: vread(buf, (char *)start, tsz); /* we have to zero-fill user buffer even if no read */ - if (copy_to_user(buffer, buf, tsz)) { + if (copy_to_iter(buf, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; case KCORE_USER: /* User page is handled prior to normal kernel page: */ - if (copy_to_user(buffer, (char *)start, tsz)) { + if (copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -531,7 +532,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) */ if (!page || PageOffline(page) || is_page_hwpoison(page) || !pfn_is_ram(pfn)) { - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -541,25 +542,24 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) case KCORE_VMEMMAP: case KCORE_TEXT: /* - * We use _copy_to_user() to bypass usermode hardening + * We use _copy_to_iter() to bypass usermode hardening * which would otherwise prevent this operation. */ - if (_copy_to_user(buffer, (char *)start, tsz)) { + if (_copy_to_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } break; default: pr_warn_once("Unhandled KCORE type: %d\n", m->type); - if (clear_user(buffer, tsz)) { + if (iov_iter_zero(tsz, iter) != tsz) { ret = -EFAULT; goto out; } } skip: buflen -= tsz; - *fpos += tsz; - buffer += tsz; + *ppos += tsz; start += tsz; tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } @@ -603,7 +603,7 @@ static int release_kcore(struct inode *inode, struct file *file) } static const struct proc_ops kcore_proc_ops = { - .proc_read = read_kcore, + .proc_read_iter = read_kcore_iter, .proc_open = open_kcore, .proc_release = release_kcore, .proc_lseek = default_llseek,