arch/s390/kernel/cpcmd.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  S390 version
 *    Copyright IBM Corp. 1999, 2007
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *               Christian Borntraeger (cborntra@de.ibm.com),
 */

#define KMSG_COMPONENT "cpcmd"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/io.h>
#include <asm/diag.h>
#include <asm/ebcdic.h>
#include <asm/cpcmd.h>

static DEFINE_SPINLOCK(cpcmd_lock);
static char cpcmd_buf[241];

static int diag8_noresponse(int cmdlen)
{
	asm volatile(
		"	diag	%[rx],%[ry],0x8\n"
		: [ry] "+&d" (cmdlen)
		: [rx] "d" (__pa(cpcmd_buf))
		: "cc");
	return cmdlen;
}

static int diag8_response(int cmdlen, char *response, int *rlen)
{
	union register_pair rx, ry;
	int cc;

	rx.even = __pa(cpcmd_buf);
	rx.odd	= __pa(response);
	ry.even = cmdlen | 0x40000000L;
	ry.odd	= *rlen;
	asm volatile(
		"	diag	%[rx],%[ry],0x8\n"
		"	ipm	%[cc]\n"
		"	srl	%[cc],28\n"
		: [cc] "=&d" (cc), [ry] "+&d" (ry.pair)
		: [rx] "d" (rx.pair)
		: "cc");
	if (cc)
		*rlen += ry.odd;
	else
		*rlen = ry.odd;
	return ry.even;
}

/*
 * __cpcmd has some restrictions over cpcmd
 *  - __cpcmd is unlocked and therefore not SMP-safe
 */
int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
	int cmdlen;
	int rc;
	int response_len;

	cmdlen = strlen(cmd);
	BUG_ON(cmdlen > 240);
	memcpy(cpcmd_buf, cmd, cmdlen);
	ASCEBC(cpcmd_buf, cmdlen);

	diag_stat_inc(DIAG_STAT_X008);
	if (response) {
		memset(response, 0, rlen);
		response_len = rlen;
		rc = diag8_response(cmdlen, response, &rlen);
		EBCASC(response, response_len);
        } else {
		rc = diag8_noresponse(cmdlen);
        }
	if (response_code)
		*response_code = rc;
	return rlen;
}
EXPORT_SYMBOL(__cpcmd);

int cpcmd(const char *cmd, char *response, int rlen, int *response_code)
{
	unsigned long flags;
	char *lowbuf;
	int len;

	if (is_vmalloc_or_module_addr(response)) {
		lowbuf = kmalloc(rlen, GFP_KERNEL);
		if (!lowbuf) {
			pr_warn("The cpcmd kernel function failed to allocate a response buffer\n");
			return -ENOMEM;
		}
		spin_lock_irqsave(&cpcmd_lock, flags);
		len = __cpcmd(cmd, lowbuf, rlen, response_code);
		spin_unlock_irqrestore(&cpcmd_lock, flags);
		memcpy(response, lowbuf, rlen);
		kfree(lowbuf);
	} else {
		spin_lock_irqsave(&cpcmd_lock, flags);
		len = __cpcmd(cmd, response, rlen, response_code);
		spin_unlock_irqrestore(&cpcmd_lock, flags);
	}
	return len;
}
EXPORT_SYMBOL(cpcmd);