[RFC] powerpc/pseries: delete scanlog

Tyrel Datwyler tyreld at linux.ibm.com
Tue May 4 06:38:23 AEST 2021


On 5/3/21 10:18 AM, Nathan Lynch wrote:
> A commit from 2008 says this driver was relevant only for "older
> systems", and currently supported hardware doesn't have this
> facility. Get rid of it.

The only references I could find to scan log dump support are several Power 4+
systems, in particular the IntelliStation POWER 9114 and pSeries 615, which were
released in 2003 at the same time this code was originally introduced.

Historical Linux commit form February 2003:
https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=f92e361842d5251e50562b09664082dcbd0548bb

IntelliStation and pSeries docs:
http://ps-2.retropc.se/basil.holloway/ALL%20PDF/380635.pdf
http://ps-2.kev009.com/rs6000/manuals/p/p615-6C3-6E3/6C3_and_6E3_Users_Guide_SA38-0629.pdf

Current firmware RTAS implementations have no reference to ibm,scan-log-dump,
and a long standing developer for that code has no recollection of its existence.

This appears to be a straggler from RPA and Power 4 days. Based on my
understanding that we dropped support Power 4 in mainline this looks pretty
orphaned to me and a solid candidate for removal barring and insight from
someone else that knows better.

+1

Feel free to add my RB tag to any non-RFC followup.

Reviewed-by: Tyrel Datwyler <tyreld at linux.ibm.com>

> 
> Signed-off-by: Nathan Lynch <nathanl at linux.ibm.com>
> ---
>  arch/powerpc/configs/ppc64_defconfig     |   1 -
>  arch/powerpc/configs/pseries_defconfig   |   1 -
>  arch/powerpc/platforms/pseries/Kconfig   |   4 -
>  arch/powerpc/platforms/pseries/Makefile  |   1 -
>  arch/powerpc/platforms/pseries/scanlog.c | 195 -----------------------
>  5 files changed, 202 deletions(-)
>  delete mode 100644 arch/powerpc/platforms/pseries/scanlog.c
> 
> diff --git a/arch/powerpc/configs/ppc64_defconfig b/arch/powerpc/configs/ppc64_defconfig
> index 701811c91a6f..acf13b4917c4 100644
> --- a/arch/powerpc/configs/ppc64_defconfig
> +++ b/arch/powerpc/configs/ppc64_defconfig
> @@ -26,7 +26,6 @@ CONFIG_PPC64=y
>  CONFIG_NR_CPUS=2048
>  CONFIG_PPC_SPLPAR=y
>  CONFIG_DTL=y
> -CONFIG_SCANLOG=m
>  CONFIG_PPC_SMLPAR=y
>  CONFIG_IBMEBUS=y
>  CONFIG_PPC_SVM=y
> diff --git a/arch/powerpc/configs/pseries_defconfig b/arch/powerpc/configs/pseries_defconfig
> index 50168dde4ea5..d120321e4eea 100644
> --- a/arch/powerpc/configs/pseries_defconfig
> +++ b/arch/powerpc/configs/pseries_defconfig
> @@ -38,7 +38,6 @@ CONFIG_MODULE_SRCVERSION_ALL=y
>  CONFIG_PARTITION_ADVANCED=y
>  CONFIG_PPC_SPLPAR=y
>  CONFIG_DTL=y
> -CONFIG_SCANLOG=m
>  CONFIG_PPC_SMLPAR=y
>  CONFIG_IBMEBUS=y
>  CONFIG_PAPR_SCM=m
> diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
> index 5e037df2a3a1..bf9b612a929b 100644
> --- a/arch/powerpc/platforms/pseries/Kconfig
> +++ b/arch/powerpc/platforms/pseries/Kconfig
> @@ -61,10 +61,6 @@ config PSERIES_ENERGY
>  	  Provides: /sys/devices/system/cpu/pseries_(de)activation_hint_list
>  	  and /sys/devices/system/cpu/cpuN/pseries_(de)activation_hint
> 
> -config SCANLOG
> -	tristate "Scanlog dump interface"
> -	depends on RTAS_PROC && PPC_PSERIES
> -
>  config IO_EVENT_IRQ
>  	bool "IO Event Interrupt support"
>  	depends on PPC_PSERIES
> diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
> index c8a2b0b05ac0..754d1102de08 100644
> --- a/arch/powerpc/platforms/pseries/Makefile
> +++ b/arch/powerpc/platforms/pseries/Makefile
> @@ -8,7 +8,6 @@ obj-y			:= lpar.o hvCall.o nvram.o reconfig.o \
>  			   firmware.o power.o dlpar.o mobility.o rng.o \
>  			   pci.o pci_dlpar.o eeh_pseries.o msi.o
>  obj-$(CONFIG_SMP)	+= smp.o
> -obj-$(CONFIG_SCANLOG)	+= scanlog.o
>  obj-$(CONFIG_KEXEC_CORE)	+= kexec.o
>  obj-$(CONFIG_PSERIES_ENERGY)	+= pseries_energy.o
> 
> diff --git a/arch/powerpc/platforms/pseries/scanlog.c b/arch/powerpc/platforms/pseries/scanlog.c
> deleted file mode 100644
> index 2879c4f0ceb7..000000000000
> --- a/arch/powerpc/platforms/pseries/scanlog.c
> +++ /dev/null
> @@ -1,195 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0-or-later
> -/*
> - *  c 2001 PPC 64 Team, IBM Corp
> - *
> - * scan-log-data driver for PPC64  Todd Inglett <tinglett at vnet.ibm.com>
> - *
> - * When ppc64 hardware fails the service processor dumps internal state
> - * of the system.  After a reboot the operating system can access a dump
> - * of this data using this driver.  A dump exists if the device-tree
> - * /chosen/ibm,scan-log-data property exists.
> - *
> - * This driver exports /proc/powerpc/scan-log-dump which can be read.
> - * The driver supports only sequential reads.
> - *
> - * The driver looks at a write to the driver for the single word "reset".
> - * If given, the driver will reset the scanlog so the platform can free it.
> - */
> -
> -#include <linux/module.h>
> -#include <linux/types.h>
> -#include <linux/errno.h>
> -#include <linux/proc_fs.h>
> -#include <linux/init.h>
> -#include <linux/delay.h>
> -#include <linux/slab.h>
> -#include <linux/uaccess.h>
> -#include <asm/rtas.h>
> -#include <asm/prom.h>
> -
> -#define MODULE_VERS "1.0"
> -#define MODULE_NAME "scanlog"
> -
> -/* Status returns from ibm,scan-log-dump */
> -#define SCANLOG_COMPLETE 0
> -#define SCANLOG_HWERROR -1
> -#define SCANLOG_CONTINUE 1
> -
> -
> -static unsigned int ibm_scan_log_dump;			/* RTAS token */
> -static unsigned int *scanlog_buffer;			/* The data buffer */
> -
> -static ssize_t scanlog_read(struct file *file, char __user *buf,
> -			    size_t count, loff_t *ppos)
> -{
> -	unsigned int *data = scanlog_buffer;
> -	int status;
> -	unsigned long len, off;
> -	unsigned int wait_time;
> -
> -	if (count > RTAS_DATA_BUF_SIZE)
> -		count = RTAS_DATA_BUF_SIZE;
> -
> -	if (count < 1024) {
> -		/* This is the min supported by this RTAS call.  Rather
> -		 * than do all the buffering we insist the user code handle
> -		 * larger reads.  As long as cp works... :)
> -		 */
> -		printk(KERN_ERR "scanlog: cannot perform a small read (%ld)\n", count);
> -		return -EINVAL;
> -	}
> -
> -	if (!access_ok(buf, count))
> -		return -EFAULT;
> -
> -	for (;;) {
> -		wait_time = 500;	/* default wait if no data */
> -		spin_lock(&rtas_data_buf_lock);
> -		memcpy(rtas_data_buf, data, RTAS_DATA_BUF_SIZE);
> -		status = rtas_call(ibm_scan_log_dump, 2, 1, NULL,
> -				   (u32) __pa(rtas_data_buf), (u32) count);
> -		memcpy(data, rtas_data_buf, RTAS_DATA_BUF_SIZE);
> -		spin_unlock(&rtas_data_buf_lock);
> -
> -		pr_debug("scanlog: status=%d, data[0]=%x, data[1]=%x, " \
> -			 "data[2]=%x\n", status, data[0], data[1], data[2]);
> -		switch (status) {
> -		    case SCANLOG_COMPLETE:
> -			pr_debug("scanlog: hit eof\n");
> -			return 0;
> -		    case SCANLOG_HWERROR:
> -			pr_debug("scanlog: hardware error reading data\n");
> -			return -EIO;
> -		    case SCANLOG_CONTINUE:
> -			/* We may or may not have data yet */
> -			len = data[1];
> -			off = data[2];
> -			if (len > 0) {
> -				if (copy_to_user(buf, ((char *)data)+off, len))
> -					return -EFAULT;
> -				return len;
> -			}
> -			/* Break to sleep default time */
> -			break;
> -		    default:
> -			/* Assume extended busy */
> -			wait_time = rtas_busy_delay_time(status);
> -			if (!wait_time) {
> -				printk(KERN_ERR "scanlog: unknown error " \
> -				       "from rtas: %d\n", status);
> -				return -EIO;
> -			}
> -		}
> -		/* Apparently no data yet.  Wait and try again. */
> -		msleep_interruptible(wait_time);
> -	}
> -	/*NOTREACHED*/
> -}
> -
> -static ssize_t scanlog_write(struct file * file, const char __user * buf,
> -			     size_t count, loff_t *ppos)
> -{
> -	char stkbuf[20];
> -	int status;
> -
> -	if (count > 19) count = 19;
> -	if (copy_from_user (stkbuf, buf, count)) {
> -		return -EFAULT;
> -	}
> -	stkbuf[count] = 0;
> -
> -	if (buf) {
> -		if (strncmp(stkbuf, "reset", 5) == 0) {
> -			pr_debug("scanlog: reset scanlog\n");
> -			status = rtas_call(ibm_scan_log_dump, 2, 1, NULL, 0, 0);
> -			pr_debug("scanlog: rtas returns %d\n", status);
> -		}
> -	}
> -	return count;
> -}
> -
> -static int scanlog_open(struct inode * inode, struct file * file)
> -{
> -	unsigned int *data = scanlog_buffer;
> -
> -	if (data[0] != 0) {
> -		/* This imperfect test stops a second copy of the
> -		 * data (or a reset while data is being copied)
> -		 */
> -		return -EBUSY;
> -	}
> -
> -	data[0] = 0;	/* re-init so we restart the scan */
> -
> -	return 0;
> -}
> -
> -static int scanlog_release(struct inode * inode, struct file * file)
> -{
> -	unsigned int *data = scanlog_buffer;
> -
> -	data[0] = 0;
> -	return 0;
> -}
> -
> -static const struct proc_ops scanlog_proc_ops = {
> -	.proc_read	= scanlog_read,
> -	.proc_write	= scanlog_write,
> -	.proc_open	= scanlog_open,
> -	.proc_release	= scanlog_release,
> -	.proc_lseek	= noop_llseek,
> -};
> -
> -static int __init scanlog_init(void)
> -{
> -	struct proc_dir_entry *ent;
> -	int err = -ENOMEM;
> -
> -	ibm_scan_log_dump = rtas_token("ibm,scan-log-dump");
> -	if (ibm_scan_log_dump == RTAS_UNKNOWN_SERVICE)
> -		return -ENODEV;
> -
> -	/* Ideally we could allocate a buffer < 4G */
> -	scanlog_buffer = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
> -	if (!scanlog_buffer)
> -		goto err;
> -
> -	ent = proc_create("powerpc/rtas/scan-log-dump", 0400, NULL,
> -			  &scanlog_proc_ops);
> -	if (!ent)
> -		goto err;
> -	return 0;
> -err:
> -	kfree(scanlog_buffer);
> -	return err;
> -}
> -
> -static void __exit scanlog_cleanup(void)
> -{
> -	remove_proc_entry("powerpc/rtas/scan-log-dump", NULL);
> -	kfree(scanlog_buffer);
> -}
> -
> -module_init(scanlog_init);
> -module_exit(scanlog_cleanup);
> -MODULE_LICENSE("GPL");
> 



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