From patchwork series 433960

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=433960

Author: Fox Snowpatch

arch/powerpc/include/uapi/asm/papr-platform-dump.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_PAPR_PLATFORM_DUMP_H_
+#define _UAPI_PAPR_PLATFORM_DUMP_H_
+
+#include <asm/ioctl.h>
+#include <asm/papr-miscdev.h>
+
+/*
+ * ioctl for /dev/papr-platform-dump. Returns a VPD handle fd corresponding to
+ * the location code.
+ */
+#define PAPR_PLATFORM_DUMP_IOC_CREATE_HANDLE _IOW(PAPR_MISCDEV_IOC_ID, 3, __u64)
+
+#endif /* _UAPI_PAPR_PLATFORM_DUMP_H_ */

arch/powerpc/platforms/pseries/Makefile

@@ -3,7 +3,7 @@ ccflags-$(CONFIG_PPC_PSERIES_DEBUG)	+= -DDEBUG
 
 obj-y			:= lpar.o hvCall.o nvram.o reconfig.o \
 			   of_helpers.o rtas-work-area.o papr-sysparm.o \
-			   papr-vpd.o \
+			   papr-vpd.o papr-platform-dump.o \
 			   setup.o iommu.o event_sources.o ras.o \
 			   firmware.o power.o dlpar.o mobility.o rng.o \
 			   pci.o pci_dlpar.o eeh_pseries.o msi.o \

arch/powerpc/platforms/pseries/papr-platform-dump.c

@@ -0,0 +1,356 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "papr-platform-dump: " fmt
+
+#include <linux/anon_inodes.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <asm/machdep.h>
+#include <asm/rtas-work-area.h>
+#include <asm/rtas.h>
+#include <uapi/asm/papr-platform-dump.h>
+
+/*
+ * Function-specific return values for ibm,platform-dump, derived from
+ * PAPR+ v2.13 7.3.3.4.1 "ibm,platform-dump RTAS Call".
+ */
+#define	RTAS_IBM_PLATFORM_DUMP_COMPLETE	0	/* Complete dump retrieved. */
+#define	RTAS_IBM_PLATFORM_DUMP_CONTINUE	1	/* Continue dump */
+#define	RTAS_NOT_AUTHORIZED		-9002	/* Not Authorized */
+
+#define	RTAS_IBM_PLATFORM_DUMP_START	2 /* Linux status to start dump */
+
+/**
+ * struct ibm_platform_dump_params - Parameters (in and out) for
+ *                                              ibm,platform-dump
+ * @work_area:	In: work area buffer for results.
+ * @buf_length:	In: work area buffer length in bytes
+ * @dump_tag:	In: Dump_Tag representing an id of the dump being processed
+ * @sequence:	In: Sequence number. Out: Next sequence number.
+ * @written:	Out: Bytes written by ibm,platform-dump to @work_area.
+ * @status:	Out: RTAS call status.
+ * @list:	Maintain the list of dumps are in progress. Can retrieve
+ *		multiple dumps with different dump IDs at the same time,
+ *		but not with the same dump ID. This list is used to
+ *		determine whether the dump for the same ID is in progress.
+ */
+struct ibm_platform_dump_params {
+	struct rtas_work_area	*work_area;
+	u32			buf_length;
+	u32			dump_tag_hi;
+	u32			dump_tag_lo;
+	u32			sequence_hi;
+	u32			sequence_lo;
+	u32			bytes_ret_hi;
+	u32			bytes_ret_lo;
+	s32			status;
+	struct list_head	list;
+};
+
+/*
+ * Multiple dumps with different dump IDs can be retrieved at the same
+ * time, but not with dame dump ID. platform_dump_list_mutex and
+ * platform_dump_list are used to prevent this behavior.
+ */
+static DEFINE_MUTEX(platform_dump_list_mutex);
+static LIST_HEAD(platform_dump_list);
+
+/**
+ * rtas_ibm_platform_dump() - Call ibm,platform-dump to fill a work area
+ * buffer.
+ * @params: See &struct ibm_platform_dump_params.
+ * @buf_addr: Address of dump buffer (work_area)
+ * @buf_length: Length of the buffer in bytes (min. 1024)
+ *
+ * Calls ibm,platform-dump until it errors or successfully deposits data
+ * into the supplied work area. Handles RTAS retry statuses. Maps RTAS
+ * error statuses to reasonable errno values.
+ *
+ * Can request multiple dumps with different dump IDs at the same time,
+ * but not with the same dump ID which is prevented with the check in
+ * the ioctl code (papr_platform_dump_create_handle()).
+ *
+ * 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 for dump complete and 1 for continue dump
+ */
+static int rtas_ibm_platform_dump(struct ibm_platform_dump_params *params,
+				phys_addr_t buf_addr, u32 buf_length)
+{
+	u32 rets[4];
+	s32 fwrc;
+	int ret = 0;
+
+	do {
+		fwrc = rtas_call(rtas_function_token(RTAS_FN_IBM_PLATFORM_DUMP),
+				6, 5,
+				rets,
+				params->dump_tag_hi,
+				params->dump_tag_lo,
+				params->sequence_hi,
+				params->sequence_lo,
+				buf_addr,
+				buf_length);
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case RTAS_HARDWARE_ERROR:
+		ret = -EIO;
+		break;
+	case RTAS_NOT_AUTHORIZED:
+		ret = -EPERM;
+		break;
+	case RTAS_IBM_PLATFORM_DUMP_CONTINUE:
+	case RTAS_IBM_PLATFORM_DUMP_COMPLETE:
+		params->sequence_hi = rets[0];
+		params->sequence_lo = rets[1];
+		params->bytes_ret_hi = rets[2];
+		params->bytes_ret_lo = rets[3];
+		break;
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("unexpected ibm,platform-dump status %d\n",
+				fwrc);
+		break;
+	}
+
+	params->status = fwrc;
+	return ret;
+}
+
+/*
+ * Platform dump is used with multiple RTAS calls to retrieve the
+ * complete dump for the provided dump ID. Once the complete dump is
+ * retrieved, the hypervisor returns dump complete status (0) for the
+ * last RTAS call and expects the caller issues one more HCALL with
+ * NULL buffer to invalidate the dump so that the hypervisor can remove
+ * the dump.
+ *
+ * After the specific dump is invalidated in the hypervisor, expect the
+ * dump complete status for the new sequence - the user space initiates
+ * new request for the same dump ID.
+ */
+static ssize_t papr_platform_dump_handle_read(struct file *file,
+		char __user *buf, size_t size, loff_t *off)
+{
+	struct ibm_platform_dump_params *params = file->private_data;
+	u64 total_bytes;
+	s32 fwrc;
+
+	/*
+	 * Dump already completed with the previous read calls.
+	 * In case if the user space issues further reads, returns
+	 * -EINVAL.
+	 */
+	if (!params->buf_length) {
+		pr_warn_once("Platform dump completed for dump ID %llu\n",
+			(u64) (((u64)params->dump_tag_hi << 32) |
+				params->dump_tag_lo));
+		return -EINVAL;
+	}
+
+	if (size < SZ_1K) {
+		pr_err_once("Buffer length should be minimum 1024 bytes\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * The hypervisor returns status 0 if no more data available to
+	 * download. Then expects the last RTAS call with NULL buffer
+	 * to invalidate the dump which means dump will be freed in the
+	 * hypervisor.
+	 */
+	if (params->status == RTAS_IBM_PLATFORM_DUMP_COMPLETE) {
+		params->buf_length = 0;
+		fwrc = rtas_ibm_platform_dump(params, 0, 0);
+		/*
+		 * Returns 0 (success) to the user space so that user
+		 * space read stops.
+		 */
+		return fwrc;
+	} else if (size > params->buf_length) {
+		/*
+		 * Allocate 4K work area. So if the user requests > 4K,
+		 * resize the buffer length.
+		 */
+		size = params->buf_length;
+	}
+
+	fwrc = rtas_ibm_platform_dump(params,
+			rtas_work_area_phys(params->work_area),
+			size);
+	if (fwrc < 0)
+		return fwrc;
+
+	total_bytes = (u64) (((u64)params->bytes_ret_hi << 32) |
+			params->bytes_ret_lo);
+
+	/*
+	 * Kernel or firmware bug, do not continue.
+	 */
+	if (WARN(total_bytes > size, "possible write beyond end of work area"))
+		return -EFAULT;
+
+	if (copy_to_user(buf, rtas_work_area_raw_buf(params->work_area),
+			total_bytes))
+		return -EFAULT;
+
+	return total_bytes;
+}
+
+static int papr_platform_dump_handle_release(struct inode *inode,
+					struct file *file)
+{
+	struct ibm_platform_dump_params *params = file->private_data;
+	s32 fwrc = 0;
+
+	if (params->work_area)
+		rtas_work_area_free(params->work_area);
+
+	mutex_lock(&platform_dump_list_mutex);
+	list_del(&params->list);
+	mutex_unlock(&platform_dump_list_mutex);
+
+	kfree(params);
+
+	return fwrc;
+}
+
+static const struct file_operations papr_platform_dump_handle_ops = {
+	.read = papr_platform_dump_handle_read,
+	.release = papr_platform_dump_handle_release,
+};
+
+/**
+ * papr_platform_dump_create_handle() - Create a fd-based handle for
+ * reading platform dump
+ *
+ * Handler for PAPR_PLATFORM_DUMP_IOC_CREATE_HANDLE ioctl command
+ * Allocates RTAS parameter struct and work area and attached to the
+ * file descriptor for reading by user space with the multiple RTAS
+ * calls until the dump is completed. This memory allocation is freed
+ * when the file is released.
+ *
+ * Multiple dump requests with different IDs are allowed at the same
+ * time, but not with the same dump ID. So if the user space is
+ * already opened file descriptor for the specific dump ID, return
+ * -EALREADY for the next request.
+ *
+ * @dump_tag: Dump ID for the dump requested to retrieve from the
+ *		hypervisor
+ *
+ * Return: The installed fd number if successful, -ve errno otherwise.
+ */
+static long papr_platform_dump_create_handle(u64 dump_tag)
+{
+	struct ibm_platform_dump_params *params;
+	u64 param_dump_tag;
+	struct file *file;
+	long err;
+	int fd;
+
+	/*
+	 * Return failure if the user space is already opened FD for
+	 * the specific dump ID. This check will prevent multiple dump
+	 * requests for the same dump ID at the same time. Generally
+	 * should not expect this, but in case.
+	 */
+	list_for_each_entry(params, &platform_dump_list, list) {
+		param_dump_tag = (u64) (((u64)params->dump_tag_hi << 32) |
+					params->bytes_ret_lo);
+		if (dump_tag == param_dump_tag) {
+			pr_err("Platform dump for ID(%llu) is already in progress\n",
+					dump_tag);
+			return -EALREADY;
+		}
+	}
+
+	params =  kzalloc(sizeof(struct ibm_platform_dump_params),
+			GFP_KERNEL_ACCOUNT);
+	if (!params)
+		return -ENOMEM;
+
+	params->work_area = rtas_work_area_alloc(SZ_4K);
+	params->buf_length = SZ_4K;
+	params->dump_tag_hi = (u32)(dump_tag >> 32);
+	params->dump_tag_lo = (u32)(dump_tag & 0x00000000ffffffffULL);
+	params->status = RTAS_IBM_PLATFORM_DUMP_START;
+
+	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		err = fd;
+		goto put_fd;
+	}
+
+	file = anon_inode_getfile("[papr-platform-dump]",
+				&papr_platform_dump_handle_ops,
+				(void *)params, O_RDONLY);
+	if (IS_ERR(file)) {
+		err = PTR_ERR(file);
+		goto put_fd;
+	}
+
+	file->f_mode |= FMODE_LSEEK | FMODE_PREAD;
+	fd_install(fd, file);
+
+	list_add(&params->list, &platform_dump_list);
+
+	pr_info("%s (%d) initiated platform dump for dump tag %llu\n",
+		current->comm, current->pid, dump_tag);
+	return fd;
+put_fd:
+	rtas_work_area_free(params->work_area);
+	kfree(params);
+	put_unused_fd(fd);
+	return err;
+}
+
+/*
+ * Top-level ioctl handler for /dev/papr-platform-dump.
+ */
+static long papr_platform_dump_dev_ioctl(struct file *filp, unsigned int ioctl,
+					unsigned long arg)
+{
+	u64 __user *argp = (void __user *)arg;
+	u64 dump_tag;
+	long ret;
+
+	if (get_user(dump_tag, argp))
+		return -EFAULT;
+
+	switch (ioctl) {
+	case PAPR_PLATFORM_DUMP_IOC_CREATE_HANDLE:
+		mutex_lock(&platform_dump_list_mutex);
+		ret = papr_platform_dump_create_handle(dump_tag);
+		mutex_unlock(&platform_dump_list_mutex);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+	return ret;
+}
+
+static const struct file_operations papr_platform_dump_ops = {
+	.unlocked_ioctl = papr_platform_dump_dev_ioctl,
+};
+
+static struct miscdevice papr_platform_dump_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "papr-platform-dump",
+	.fops = &papr_platform_dump_ops,
+};
+
+static __init int papr_platform_dump_init(void)
+{
+	if (!rtas_function_implemented(RTAS_FN_IBM_PLATFORM_DUMP))
+		return -ENODEV;
+
+	return misc_register(&papr_platform_dump_dev);
+}
+machine_device_initcall(pseries, papr_platform_dump_init);