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Mon, 2 Nov 2026 15:11:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793632290; bh=Veri64uIgSpvDnn8LOw8Zp4yMSBZFCckYlFRYYQC2Vw=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=PyH2KrOvZD+BL9zUl6AU8BXeJKg3ikWP80JWS5gYZgMQV/kTMBB7CrV1pMxIJKL4f ztIp9wftXZwnWLrgNLehHtxksIhWl4dHOxqRJBldIuhEhovhTDw55IVzZ9TROxDjjW XA3pUmsiO+q6HP7XdahCpcrGPElFCvPN3654lH68oxzD+xgivEgvKHiEVuaV9AbVh7 gyekICA6wkoIzDKxIYuvGIz/7JyEv4UkOBjueUDWmWdaMOfSLMFTmp8c9Hk+Fh9e52 reAWSbDO2KsmTnQ5LN9feY66XkFi20tGnzFSkSmvDBITpiXfojEd7sdGjrZi3hZ2oI HUDwrYxyBrmbQ== From: Christian Brauner Date: Mon, 02 Nov 2026 16:07:11 +0100 Subject: [PATCH RFC 04/23] PCI/proc: let procfs copy out config space reads X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-drivers-v1-4-a994bd4d3b1a@kernel.org> References: <20261102-work-procfs-drivers-v1-0-a994bd4d3b1a@kernel.org> In-Reply-To: <20261102-work-procfs-drivers-v1-0-a994bd4d3b1a@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=3228; i=brauner@kernel.org; h=from:subject:message-id; bh=jf9xs+FhfBfS3vas7oIWufWfAbP2hJLFKyaoEXyHsWk=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9WG5wN0zQ9uaOcyyafDNO7BVlT6yIqtn0O/D5wm0tX HyZC1w2dpSyMIhxMciKKbI4tJuEyy3nqdhslKkBM4eVCWQIAxenAExk/wWGv/JrO7p2sJvf/nju 4TeP5aUBLptarsV2/Ve9+3Wq/HwZljUM/2OVDpj3tT+a1faKoWnzHc6CF5vXOViwS7hZp5smJdi asAIA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 Implement ->proc_read_buf() so procfs copies what is read to userspace after it unpinned the entry, and read the config space into procfs' buffer with put_unaligned_le16() and put_unaligned_le32() instead of put_user(). A read into a buffer that can't be written used to report success. It fails with -EFAULT now. A page holds all of the config space, so a single read of it still works, libpci treats a short read as an error. Signed-off-by: Christian Brauner (Amutable) --- drivers/pci/proc.c | 19 ++++++++----------- 1 file changed, 8 insertions(+), 11 deletions(-) diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c index d420353ee2b3..a8d7469f222b 100644 --- a/drivers/pci/proc.c +++ b/drivers/pci/proc.c @@ -29,8 +29,8 @@ static loff_t proc_bus_pci_lseek(struct file *file, loff_t off, int whence) return fixed_size_llseek(file, off, whence, dev->cfg_size); } -static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, - size_t nbytes, loff_t *ppos) +static ssize_t proc_bus_pci_read(struct file *file, char *buf, size_t nbytes, + loff_t *ppos) { struct pci_dev *dev = pde_data(file_inode(file)); unsigned int pos, cnt, size; @@ -60,15 +60,12 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, nbytes = size - pos; cnt = nbytes; - if (!access_ok(buf, cnt)) - return -EINVAL; - pci_config_pm_runtime_get(dev); if ((pos & 1) && cnt) { unsigned char val; pci_user_read_config_byte(dev, pos, &val); - put_user(val, buf); + *buf = val; buf++; pos++; cnt--; @@ -77,7 +74,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, if ((pos & 3) && cnt > 2) { unsigned short val; pci_user_read_config_word(dev, pos, &val); - put_user(cpu_to_le16(val), (__le16 __user *) buf); + put_unaligned_le16(val, buf); buf += 2; pos += 2; cnt -= 2; @@ -86,7 +83,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, while (cnt >= 4) { unsigned int val; pci_user_read_config_dword(dev, pos, &val); - put_user(cpu_to_le32(val), (__le32 __user *) buf); + put_unaligned_le32(val, buf); buf += 4; pos += 4; cnt -= 4; @@ -96,7 +93,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, if (cnt >= 2) { unsigned short val; pci_user_read_config_word(dev, pos, &val); - put_user(cpu_to_le16(val), (__le16 __user *) buf); + put_unaligned_le16(val, buf); buf += 2; pos += 2; cnt -= 2; @@ -105,7 +102,7 @@ static ssize_t proc_bus_pci_read(struct file *file, char __user *buf, if (cnt) { unsigned char val; pci_user_read_config_byte(dev, pos, &val); - put_user(val, buf); + *buf = val; pos++; } @@ -327,7 +324,7 @@ static int proc_bus_pci_release(struct inode *inode, struct file *file) static const struct proc_ops proc_bus_pci_ops = { .proc_flags = PROC_ENTRY_SHORT_WRITES, .proc_lseek = proc_bus_pci_lseek, - .proc_read = proc_bus_pci_read, + .proc_read_buf = proc_bus_pci_read, .proc_write_buf = proc_bus_pci_write, .proc_write_size = PCI_CFG_SPACE_EXP_SIZE, .proc_ioctl = proc_bus_pci_ioctl, -- 2.53.0