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: Nico Boehr <nrb@linux.ibm.com>
Co-developed-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Signed-off-by: Janis 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: Heiko Carstens <hca@linux.ibm.com>
diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index a596e69..8a5d214 100644
--- a/arch/s390/lib/uaccess.c
+++ b/arch/s390/lib/uaccess.c
@@ -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;
}