Commit 012a224e authored by Nico Boehr's avatar Nico Boehr Committed by Heiko Carstens
Browse files

s390/uaccess: introduce bit field for OAC specifier 



Previously, we've used  magic values to specify the OAC
(operand-access control) for mvcos.

Instead we introduce a bit field for it.

When using a bit field, we cannot use an immediate value with K
constraint anymore, since GCC older than 10 doesn't recognize
the bit field union as a compile time constant.
To make things work with older compilers,
load the OAC value through a register.

Bloat-o-meter reports a slight increase in kernel size with this change:
Total: Before=15692135, After=15693015, chg +0.01%

Signed-off-by: default avatarNico Boehr <nrb@linux.ibm.com>
Co-developed-by: default avatarJanis Schoetterl-Glausch <scgl@linux.ibm.com>
Signed-off-by: default avatarJanis Schoetterl-Glausch <scgl@linux.ibm.com>
Link: https://lore.kernel.org/r/20220111100003.743116-1-scgl@linux.ibm.com


Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 745f5d20

arch/s390/include/asm/uaccess.h

+77 −43
Original line number Diff line number Diff line
@@ -49,12 +49,34 @@ int __get_user_bad(void) __attribute__((noreturn)); 


#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES



#define __put_get_user_asm(to, from, size, insn)		\

union oac {

	unsigned int val;

	struct {

		struct {

			unsigned short key : 4;

			unsigned short	   : 4;

			unsigned short as  : 2;

			unsigned short	   : 4;

			unsigned short k   : 1;

			unsigned short a   : 1;

		} oac1;

		struct {

			unsigned short key : 4;

			unsigned short	   : 4;

			unsigned short as  : 2;

			unsigned short	   : 4;

			unsigned short k   : 1;

			unsigned short a   : 1;

		} oac2;

	};

};



#define __put_get_user_asm(to, from, size, oac_spec)			\

({									\

	int __rc;							\

									\

	asm volatile(							\

		insn "		0,%[spec]\n"			\

		"	lr	0,%[spec]\n"				\

		"0:	mvcos	%[_to],%[_from],%[_size]\n"		\

		"1:	xr	%[rc],%[rc]\n"				\

		"2:\n"							\
@@ -65,35 +87,47 @@ int __get_user_bad(void) __attribute__((noreturn)); 
		EX_TABLE(0b,3b) EX_TABLE(1b,3b)				\

		: [rc] "=&d" (__rc), [_to] "+Q" (*(to))			\

		: [_size] "d" (size), [_from] "Q" (*(from)),		\

		  [retval] "K" (-EFAULT), [spec] "K" (0x81UL)	\

		  [retval] "K" (-EFAULT), [spec] "d" (oac_spec.val)	\

		: "cc", "0");						\

	__rc;								\

})



#define __put_user_asm(to, from, size)				\

	__put_get_user_asm(to, from, size, ((union oac) {	\

		.oac1.as = PSW_BITS_AS_SECONDARY,		\

		.oac1.a = 1					\

	}))



#define __get_user_asm(to, from, size)				\

	__put_get_user_asm(to, from, size, ((union oac) {	\

		.oac2.as = PSW_BITS_AS_SECONDARY,		\

		.oac2.a = 1					\

	}))							\



static __always_inline int __put_user_fn(void *x, void __user *ptr, unsigned long size)

{

	int rc;



	switch (size) {

	case 1:

		rc = __put_get_user_asm((unsigned char __user *)ptr,

		rc = __put_user_asm((unsigned char __user *)ptr,

				    (unsigned char *)x,

					size, "llilh");

				    size);

		break;

	case 2:

		rc = __put_get_user_asm((unsigned short __user *)ptr,

		rc = __put_user_asm((unsigned short __user *)ptr,

				    (unsigned short *)x,

					size, "llilh");

				    size);

		break;

	case 4:

		rc = __put_get_user_asm((unsigned int __user *)ptr,

		rc = __put_user_asm((unsigned int __user *)ptr,

				    (unsigned int *)x,

					size, "llilh");

				    size);

		break;

	case 8:

		rc = __put_get_user_asm((unsigned long __user *)ptr,

		rc = __put_user_asm((unsigned long __user *)ptr,

				    (unsigned long *)x,

					size, "llilh");

				    size);

		break;

	default:

		__put_user_bad();
@@ -108,24 +142,24 @@ static __always_inline int __get_user_fn(void *x, const void __user *ptr, unsign 


	switch (size) {

	case 1:

		rc = __put_get_user_asm((unsigned char *)x,

		rc = __get_user_asm((unsigned char *)x,

				    (unsigned char __user *)ptr,

					size, "lghi");

				    size);

		break;

	case 2:

		rc = __put_get_user_asm((unsigned short *)x,

		rc = __get_user_asm((unsigned short *)x,

				    (unsigned short __user *)ptr,

					size, "lghi");

				    size);

		break;

	case 4:

		rc = __put_get_user_asm((unsigned int *)x,

		rc = __get_user_asm((unsigned int *)x,

				    (unsigned int __user *)ptr,

					size, "lghi");

				    size);

		break;

	case 8:

		rc = __put_get_user_asm((unsigned long *)x,

		rc = __get_user_asm((unsigned long *)x,

				    (unsigned long __user *)ptr,

					size, "lghi");

				    size);

		break;

	default:

		__get_user_bad();

arch/s390/lib/uaccess.c

+18 −6
Original line number Diff line number Diff line
@@ -62,10 +62,14 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr 
						 unsigned long size)

{

	unsigned long tmp1, tmp2;

	union oac spec = {

		.oac2.as = PSW_BITS_AS_SECONDARY,

		.oac2.a = 1,

	};



	tmp1 = -4096UL;

	asm volatile(

		"   lghi  0,%[spec]\n"

		"   lr	  0,%[spec]\n"

		"0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"

		"6: jz    4f\n"

		"1: algr  %0,%3\n"
@@ -84,7 +88,7 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr 
		"5:\n"

		EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)

		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)

		: [spec] "K" (0x81UL)

		: [spec] "d" (spec.val)

		: "cc", "memory", "0");

	return size;

}
@@ -135,10 +139,14 @@ static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x, 
					       unsigned long size)

{

	unsigned long tmp1, tmp2;

	union oac spec = {

		.oac1.as = PSW_BITS_AS_SECONDARY,

		.oac1.a = 1,

	};



	tmp1 = -4096UL;

	asm volatile(

		"   llilh 0,%[spec]\n"

		"   lr	  0,%[spec]\n"

		"0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"

		"6: jz    4f\n"

		"1: algr  %0,%3\n"
@@ -157,7 +165,7 @@ static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x, 
		"5:\n"

		EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)

		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)

		: [spec] "K" (0x81UL)

		: [spec] "d" (spec.val)

		: "cc", "memory", "0");

	return size;

}
@@ -207,10 +215,14 @@ EXPORT_SYMBOL(raw_copy_to_user); 
static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)

{

	unsigned long tmp1, tmp2;

	union oac spec = {

		.oac1.as = PSW_BITS_AS_SECONDARY,

		.oac1.a = 1,

	};



	tmp1 = -4096UL;

	asm volatile(

		"   llilh 0,%[spec]\n"

		"   lr	  0,%[spec]\n"

		"0: .insn ss,0xc80000000000,0(%0,%1),0(%4),0\n"

		"   jz	  4f\n"

		"1: algr  %0,%2\n"
@@ -228,7 +240,7 @@ static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size 
		"5:\n"

		EX_TABLE(0b,2b) EX_TABLE(3b,5b)

		: "+a" (size), "+a" (to), "+a" (tmp1), "=a" (tmp2)

		: "a" (empty_zero_page), [spec] "K" (0x81UL)

		: "a" (empty_zero_page), [spec] "d" (spec.val)

		: "cc", "memory", "0");

	return size;

}