Commit cd4386a9 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

s390/cpcmd,vmcp: avoid GFP_DMA allocations 



According to the CP Programming Services manual Diagnose Code 8
"Virtual Console Function" can be used in all addressing modes. Also
the input and output buffers do not have a limitation which specifies
they need to be below the 2GB line.

This is true at least since z/VM 5.4.

Therefore remove the sam31/64 instructions and allow for simple
GFP_KERNEL allocations. This makes it easier to allocate a 1MB page
if the user requested such a large return buffer.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 267239cc

arch/s390/include/asm/cpcmd.h

+3 −4
Original line number Diff line number Diff line
@@ -10,9 +10,8 @@ 


/*

 * the lowlevel function for cpcmd

 * the caller of __cpcmd has to ensure that the response buffer is below 2 GB

 */

extern int __cpcmd(const char *cmd, char *response, int rlen, int *response_code);

int __cpcmd(const char *cmd, char *response, int rlen, int *response_code);



/*

 * cpcmd is the in-kernel interface for issuing CP commands
@@ -25,8 +24,8 @@ extern int __cpcmd(const char *cmd, char *response, int rlen, int *response_code 
 * response_code: return pointer for VM's error code

 * return value: the size of the response. The caller can check if the buffer

 *		was large enough by comparing the return value and rlen

 * NOTE: If the response buffer is not below 2 GB, cpcmd can sleep

 * NOTE: If the response buffer is not in real storage, cpcmd can sleep

 */

extern int cpcmd(const char *cmd, char *response, int rlen, int *response_code);

int cpcmd(const char *cmd, char *response, int rlen, int *response_code);



#endif /* _ASM_S390_CPCMD_H */

arch/s390/kernel/cpcmd.c

+4 −9
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/spinlock.h>

#include <linux/stddef.h>

#include <linux/string.h>

#include <linux/mm.h>

#include <asm/diag.h>

#include <asm/ebcdic.h>

#include <asm/cpcmd.h>
@@ -28,9 +29,7 @@ static int diag8_noresponse(int cmdlen) 
	register unsigned long reg3 asm ("3") = cmdlen;



	asm volatile(

		"	sam31\n"

		"	diag	%1,%0,0x8\n"

		"	sam64\n"

		: "+d" (reg3) : "d" (reg2) : "cc");

	return reg3;

}
@@ -43,9 +42,7 @@ static int diag8_response(int cmdlen, char *response, int *rlen) 
	register unsigned long reg5 asm ("5") = *rlen;



	asm volatile(

		"	sam31\n"

		"	diag	%2,%0,0x8\n"

		"	sam64\n"

		"	brc	8,1f\n"

		"	agr	%1,%4\n"

		"1:\n"
@@ -57,7 +54,6 @@ static int diag8_response(int cmdlen, char *response, int *rlen) 


/*

 * __cpcmd has some restrictions over cpcmd

 *  - the response buffer must reside below 2GB (if any)

 *  - __cpcmd is unlocked and therefore not SMP-safe

 */

int  __cpcmd(const char *cmd, char *response, int rlen, int *response_code)
@@ -88,13 +84,12 @@ EXPORT_SYMBOL(__cpcmd); 


int cpcmd(const char *cmd, char *response, int rlen, int *response_code)

{

	unsigned long flags;

	char *lowbuf;

	int len;

	unsigned long flags;



	if ((virt_to_phys(response) != (unsigned long) response) ||

			(((unsigned long)response + rlen) >> 31)) {

		lowbuf = kmalloc(rlen, GFP_KERNEL | GFP_DMA);

	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;

drivers/s390/char/vmcp.c

+1 −1
Original line number Diff line number Diff line
@@ -98,7 +98,7 @@ vmcp_write(struct file *file, const char __user *buff, size_t count, 
	}

	if (!session->response)

		session->response = (char *)__get_free_pages(GFP_KERNEL

						| __GFP_RETRY_MAYFAIL | GFP_DMA,

						| __GFP_RETRY_MAYFAIL,

						get_order(session->bufsize));

	if (!session->response) {

		mutex_unlock(&session->mutex);

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