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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:36 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-18 18:50:36 +0000 |
commit | 50ba0232fd5312410f1b65247e774244f89a628e (patch) | |
tree | fd8f2fc78e9e548af0ff9590276602ee6125be00 /arch/powerpc/platforms/pseries/papr-vpd.c | |
parent | Releasing progress-linux version 6.7.12-1~progress7.99u1. (diff) | |
download | linux-50ba0232fd5312410f1b65247e774244f89a628e.tar.xz linux-50ba0232fd5312410f1b65247e774244f89a628e.zip |
Merging upstream version 6.8.9.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/powerpc/platforms/pseries/papr-vpd.c')
-rw-r--r-- | arch/powerpc/platforms/pseries/papr-vpd.c | 541 |
1 files changed, 541 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/pseries/papr-vpd.c b/arch/powerpc/platforms/pseries/papr-vpd.c new file mode 100644 index 0000000000..c29e85db5f --- /dev/null +++ b/arch/powerpc/platforms/pseries/papr-vpd.c @@ -0,0 +1,541 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#define pr_fmt(fmt) "papr-vpd: " fmt + +#include <linux/anon_inodes.h> +#include <linux/build_bug.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/lockdep.h> +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/signal.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/string_helpers.h> +#include <linux/uaccess.h> +#include <asm/machdep.h> +#include <asm/papr-vpd.h> +#include <asm/rtas-work-area.h> +#include <asm/rtas.h> +#include <uapi/asm/papr-vpd.h> + +/* + * Function-specific return values for ibm,get-vpd, derived from PAPR+ + * v2.13 7.3.20 "ibm,get-vpd RTAS Call". + */ +#define RTAS_IBM_GET_VPD_COMPLETE 0 /* All VPD has been retrieved. */ +#define RTAS_IBM_GET_VPD_MORE_DATA 1 /* More VPD is available. */ +#define RTAS_IBM_GET_VPD_START_OVER -4 /* VPD changed, restart call sequence. */ + +/** + * struct rtas_ibm_get_vpd_params - Parameters (in and out) for ibm,get-vpd. + * @loc_code: In: Caller-provided location code buffer. Must be RTAS-addressable. + * @work_area: In: Caller-provided work area buffer for results. + * @sequence: In: Sequence number. Out: Next sequence number. + * @written: Out: Bytes written by ibm,get-vpd to @work_area. + * @status: Out: RTAS call status. + */ +struct rtas_ibm_get_vpd_params { + const struct papr_location_code *loc_code; + struct rtas_work_area *work_area; + u32 sequence; + u32 written; + s32 status; +}; + +/** + * rtas_ibm_get_vpd() - Call ibm,get-vpd to fill a work area buffer. + * @params: See &struct rtas_ibm_get_vpd_params. + * + * Calls ibm,get-vpd until it errors or successfully deposits data + * into the supplied work area. Handles RTAS retry statuses. Maps RTAS + * error statuses to reasonable errno values. + * + * The caller is expected to invoke rtas_ibm_get_vpd() multiple times + * to retrieve all the VPD for the provided location code. Only one + * sequence should be in progress at any time; starting a new sequence + * will disrupt any sequence already in progress. Serialization of VPD + * retrieval sequences is the responsibility of the caller. + * + * The caller should inspect @params.status to determine whether more + * calls are needed to complete the sequence. + * + * Context: May sleep. + * Return: -ve on error, 0 otherwise. + */ +static int rtas_ibm_get_vpd(struct rtas_ibm_get_vpd_params *params) +{ + const struct papr_location_code *loc_code = params->loc_code; + struct rtas_work_area *work_area = params->work_area; + u32 rets[2]; + s32 fwrc; + int ret; + + lockdep_assert_held(&rtas_ibm_get_vpd_lock); + + do { + fwrc = rtas_call(rtas_function_token(RTAS_FN_IBM_GET_VPD), 4, 3, + rets, + __pa(loc_code), + rtas_work_area_phys(work_area), + rtas_work_area_size(work_area), + params->sequence); + } while (rtas_busy_delay(fwrc)); + + switch (fwrc) { + case RTAS_HARDWARE_ERROR: + ret = -EIO; + break; + case RTAS_INVALID_PARAMETER: + ret = -EINVAL; + break; + case RTAS_IBM_GET_VPD_START_OVER: + ret = -EAGAIN; + break; + case RTAS_IBM_GET_VPD_MORE_DATA: + params->sequence = rets[0]; + fallthrough; + case RTAS_IBM_GET_VPD_COMPLETE: + params->written = rets[1]; + /* + * Kernel or firmware bug, do not continue. + */ + if (WARN(params->written > rtas_work_area_size(work_area), + "possible write beyond end of work area")) + ret = -EFAULT; + else + ret = 0; + break; + default: + ret = -EIO; + pr_err_ratelimited("unexpected ibm,get-vpd status %d\n", fwrc); + break; + } + + params->status = fwrc; + return ret; +} + +/* + * Internal VPD "blob" APIs for accumulating ibm,get-vpd results into + * an immutable buffer to be attached to a file descriptor. + */ +struct vpd_blob { + const char *data; + size_t len; +}; + +static bool vpd_blob_has_data(const struct vpd_blob *blob) +{ + return blob->data && blob->len; +} + +static void vpd_blob_free(const struct vpd_blob *blob) +{ + if (blob) { + kvfree(blob->data); + kfree(blob); + } +} + +/** + * vpd_blob_extend() - Append data to a &struct vpd_blob. + * @blob: The blob to extend. + * @data: The new data to append to @blob. + * @len: The length of @data. + * + * Context: May sleep. + * Return: -ENOMEM on allocation failure, 0 otherwise. + */ +static int vpd_blob_extend(struct vpd_blob *blob, const char *data, size_t len) +{ + const size_t new_len = blob->len + len; + const size_t old_len = blob->len; + const char *old_ptr = blob->data; + char *new_ptr; + + new_ptr = old_ptr ? + kvrealloc(old_ptr, old_len, new_len, GFP_KERNEL_ACCOUNT) : + kvmalloc(len, GFP_KERNEL_ACCOUNT); + + if (!new_ptr) + return -ENOMEM; + + memcpy(&new_ptr[old_len], data, len); + blob->data = new_ptr; + blob->len = new_len; + return 0; +} + +/** + * vpd_blob_generate() - Construct a new &struct vpd_blob. + * @generator: Function that supplies the blob data. + * @arg: Context pointer supplied by caller, passed to @generator. + * + * The @generator callback is invoked until it returns NULL. @arg is + * passed to @generator in its first argument on each call. When + * @generator returns data, it should store the data length in its + * second argument. + * + * Context: May sleep. + * Return: A completely populated &struct vpd_blob, or NULL on error. + */ +static const struct vpd_blob * +vpd_blob_generate(const char * (*generator)(void *, size_t *), void *arg) +{ + struct vpd_blob *blob; + const char *buf; + size_t len; + int err = 0; + + blob = kzalloc(sizeof(*blob), GFP_KERNEL_ACCOUNT); + if (!blob) + return NULL; + + while (err == 0 && (buf = generator(arg, &len))) + err = vpd_blob_extend(blob, buf, len); + + if (err != 0 || !vpd_blob_has_data(blob)) + goto free_blob; + + return blob; +free_blob: + vpd_blob_free(blob); + return NULL; +} + +/* + * Internal VPD sequence APIs. A VPD sequence is a series of calls to + * ibm,get-vpd for a given location code. The sequence ends when an + * error is encountered or all VPD for the location code has been + * returned. + */ + +/** + * struct vpd_sequence - State for managing a VPD sequence. + * @error: Shall be zero as long as the sequence has not encountered an error, + * -ve errno otherwise. Use vpd_sequence_set_err() to update this. + * @params: Parameter block to pass to rtas_ibm_get_vpd(). + */ +struct vpd_sequence { + int error; + struct rtas_ibm_get_vpd_params params; +}; + +/** + * vpd_sequence_begin() - Begin a VPD retrieval sequence. + * @seq: Uninitialized sequence state. + * @loc_code: Location code that defines the scope of the VPD to return. + * + * Initializes @seq with the resources necessary to carry out a VPD + * sequence. Callers must pass @seq to vpd_sequence_end() regardless + * of whether the sequence succeeds. + * + * Context: May sleep. + */ +static void vpd_sequence_begin(struct vpd_sequence *seq, + const struct papr_location_code *loc_code) +{ + /* + * Use a static data structure for the location code passed to + * RTAS to ensure it's in the RMA and avoid a separate work + * area allocation. Guarded by the function lock. + */ + static struct papr_location_code static_loc_code; + + /* + * We could allocate the work area before acquiring the + * function lock, but that would allow concurrent requests to + * exhaust the limited work area pool for no benefit. So + * allocate the work area under the lock. + */ + mutex_lock(&rtas_ibm_get_vpd_lock); + static_loc_code = *loc_code; + *seq = (struct vpd_sequence) { + .params = { + .work_area = rtas_work_area_alloc(SZ_4K), + .loc_code = &static_loc_code, + .sequence = 1, + }, + }; +} + +/** + * vpd_sequence_end() - Finalize a VPD retrieval sequence. + * @seq: Sequence state. + * + * Releases resources obtained by vpd_sequence_begin(). + */ +static void vpd_sequence_end(struct vpd_sequence *seq) +{ + rtas_work_area_free(seq->params.work_area); + mutex_unlock(&rtas_ibm_get_vpd_lock); +} + +/** + * vpd_sequence_should_stop() - Determine whether a VPD retrieval sequence + * should continue. + * @seq: VPD sequence state. + * + * Examines the sequence error state and outputs of the last call to + * ibm,get-vpd to determine whether the sequence in progress should + * continue or stop. + * + * Return: True if the sequence has encountered an error or if all VPD for + * this sequence has been retrieved. False otherwise. + */ +static bool vpd_sequence_should_stop(const struct vpd_sequence *seq) +{ + bool done; + + if (seq->error) + return true; + + switch (seq->params.status) { + case 0: + if (seq->params.written == 0) + done = false; /* Initial state. */ + else + done = true; /* All data consumed. */ + break; + case 1: + done = false; /* More data available. */ + break; + default: + done = true; /* Error encountered. */ + break; + } + + return done; +} + +static int vpd_sequence_set_err(struct vpd_sequence *seq, int err) +{ + /* Preserve the first error recorded. */ + if (seq->error == 0) + seq->error = err; + + return seq->error; +} + +/* + * Generator function to be passed to vpd_blob_generate(). + */ +static const char *vpd_sequence_fill_work_area(void *arg, size_t *len) +{ + struct vpd_sequence *seq = arg; + struct rtas_ibm_get_vpd_params *p = &seq->params; + + if (vpd_sequence_should_stop(seq)) + return NULL; + if (vpd_sequence_set_err(seq, rtas_ibm_get_vpd(p))) + return NULL; + *len = p->written; + return rtas_work_area_raw_buf(p->work_area); +} + +/* + * Higher-level VPD retrieval code below. These functions use the + * vpd_blob_* and vpd_sequence_* APIs defined above to create fd-based + * VPD handles for consumption by user space. + */ + +/** + * papr_vpd_run_sequence() - Run a single VPD retrieval sequence. + * @loc_code: Location code that defines the scope of VPD to return. + * + * Context: May sleep. Holds a mutex and an RTAS work area for its + * duration. Typically performs multiple sleepable slab + * allocations. + * + * Return: A populated &struct vpd_blob on success. Encoded error + * pointer otherwise. + */ +static const struct vpd_blob *papr_vpd_run_sequence(const struct papr_location_code *loc_code) +{ + const struct vpd_blob *blob; + struct vpd_sequence seq; + + vpd_sequence_begin(&seq, loc_code); + blob = vpd_blob_generate(vpd_sequence_fill_work_area, &seq); + if (!blob) + vpd_sequence_set_err(&seq, -ENOMEM); + vpd_sequence_end(&seq); + + if (seq.error) { + vpd_blob_free(blob); + return ERR_PTR(seq.error); + } + + return blob; +} + +/** + * papr_vpd_retrieve() - Return the VPD for a location code. + * @loc_code: Location code that defines the scope of VPD to return. + * + * Run VPD sequences against @loc_code until a blob is successfully + * instantiated, or a hard error is encountered, or a fatal signal is + * pending. + * + * Context: May sleep. + * Return: A fully populated VPD blob when successful. Encoded error + * pointer otherwise. + */ +static const struct vpd_blob *papr_vpd_retrieve(const struct papr_location_code *loc_code) +{ + const struct vpd_blob *blob; + + /* + * EAGAIN means the sequence errored with a -4 (VPD changed) + * status from ibm,get-vpd, and we should attempt a new + * sequence. PAPR+ v2.13 R1–7.3.20–5 indicates that this + * should be a transient condition, not something that happens + * continuously. But we'll stop trying on a fatal signal. + */ + do { + blob = papr_vpd_run_sequence(loc_code); + if (!IS_ERR(blob)) /* Success. */ + break; + if (PTR_ERR(blob) != -EAGAIN) /* Hard error. */ + break; + pr_info_ratelimited("VPD changed during retrieval, retrying\n"); + cond_resched(); + } while (!fatal_signal_pending(current)); + + return blob; +} + +static ssize_t papr_vpd_handle_read(struct file *file, char __user *buf, size_t size, loff_t *off) +{ + const struct vpd_blob *blob = file->private_data; + + /* bug: we should not instantiate a handle without any data attached. */ + if (!vpd_blob_has_data(blob)) { + pr_err_once("handle without data\n"); + return -EIO; + } + + return simple_read_from_buffer(buf, size, off, blob->data, blob->len); +} + +static int papr_vpd_handle_release(struct inode *inode, struct file *file) +{ + const struct vpd_blob *blob = file->private_data; + + vpd_blob_free(blob); + + return 0; +} + +static loff_t papr_vpd_handle_seek(struct file *file, loff_t off, int whence) +{ + const struct vpd_blob *blob = file->private_data; + + return fixed_size_llseek(file, off, whence, blob->len); +} + + +static const struct file_operations papr_vpd_handle_ops = { + .read = papr_vpd_handle_read, + .llseek = papr_vpd_handle_seek, + .release = papr_vpd_handle_release, +}; + +/** + * papr_vpd_create_handle() - Create a fd-based handle for reading VPD. + * @ulc: Location code in user memory; defines the scope of the VPD to + * retrieve. + * + * Handler for PAPR_VPD_IOC_CREATE_HANDLE ioctl command. Validates + * @ulc and instantiates an immutable VPD "blob" for it. The blob is + * attached to a file descriptor for reading by user space. The memory + * backing the blob is freed when the file is released. + * + * The entire requested VPD is retrieved by this call and all + * necessary RTAS interactions are performed before returning the fd + * to user space. This keeps the read handler simple and ensures that + * the kernel can prevent interleaving of ibm,get-vpd call sequences. + * + * Return: The installed fd number if successful, -ve errno otherwise. + */ +static long papr_vpd_create_handle(struct papr_location_code __user *ulc) +{ + struct papr_location_code klc; + const struct vpd_blob *blob; + struct file *file; + long err; + int fd; + + if (copy_from_user(&klc, ulc, sizeof(klc))) + return -EFAULT; + + if (!string_is_terminated(klc.str, ARRAY_SIZE(klc.str))) + return -EINVAL; + + blob = papr_vpd_retrieve(&klc); + if (IS_ERR(blob)) + return PTR_ERR(blob); + + fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC); + if (fd < 0) { + err = fd; + goto free_blob; + } + + file = anon_inode_getfile("[papr-vpd]", &papr_vpd_handle_ops, + (void *)blob, O_RDONLY); + if (IS_ERR(file)) { + err = PTR_ERR(file); + goto put_fd; + } + + file->f_mode |= FMODE_LSEEK | FMODE_PREAD; + fd_install(fd, file); + return fd; +put_fd: + put_unused_fd(fd); +free_blob: + vpd_blob_free(blob); + return err; +} + +/* + * Top-level ioctl handler for /dev/papr-vpd. + */ +static long papr_vpd_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) +{ + void __user *argp = (__force void __user *)arg; + long ret; + + switch (ioctl) { + case PAPR_VPD_IOC_CREATE_HANDLE: + ret = papr_vpd_create_handle(argp); + break; + default: + ret = -ENOIOCTLCMD; + break; + } + return ret; +} + +static const struct file_operations papr_vpd_ops = { + .unlocked_ioctl = papr_vpd_dev_ioctl, +}; + +static struct miscdevice papr_vpd_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "papr-vpd", + .fops = &papr_vpd_ops, +}; + +static __init int papr_vpd_init(void) +{ + if (!rtas_function_implemented(RTAS_FN_IBM_GET_VPD)) + return -ENODEV; + + return misc_register(&papr_vpd_dev); +} +machine_device_initcall(pseries, papr_vpd_init); |