* [PATCH] s390/uaccess: introduce bit field for OAC specifier
@ 2022-01-11 10:00 Janis Schoetterl-Glausch
2022-01-14 13:58 ` Heiko Carstens
0 siblings, 1 reply; 2+ messages in thread
From: Janis Schoetterl-Glausch @ 2022-01-11 10:00 UTC (permalink / raw)
To: Heiko Carstens, Vasily Gorbik, Christian Borntraeger,
Sven Schnelle, Nico Boehr
Cc: Alexander Gordeev, linux-s390, linux-kernel, Janis Schoetterl-Glausch
From: Nico Boehr <nrb@linux.ibm.com>
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>
---
arch/s390/include/asm/uaccess.h | 120 ++++++++++++++++++++------------
arch/s390/lib/uaccess.c | 24 +++++--
2 files changed, 95 insertions(+), 49 deletions(-)
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index ce550d06abc3..02b467461163 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -49,51 +49,85 @@ int __get_user_bad(void) __attribute__((noreturn));
#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
+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, insn) \
-({ \
- int __rc; \
- \
- asm volatile( \
- insn " 0,%[spec]\n" \
- "0: mvcos %[_to],%[_from],%[_size]\n" \
- "1: xr %[rc],%[rc]\n" \
- "2:\n" \
- ".pushsection .fixup, \"ax\"\n" \
- "3: lhi %[rc],%[retval]\n" \
- " jg 2b\n" \
- ".popsection\n" \
- 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) \
- : "cc", "0"); \
- __rc; \
+#define __put_get_user_asm(to, from, size, oac_spec) \
+({ \
+ int __rc; \
+ \
+ asm volatile( \
+ "lr 0,%[spec]\n" \
+ "0: mvcos %[_to],%[_from],%[_size]\n" \
+ "1: xr %[rc],%[rc]\n" \
+ "2:\n" \
+ ".pushsection .fixup, \"ax\"\n" \
+ "3: lhi %[rc],%[retval]\n" \
+ " jg 2b\n" \
+ ".popsection\n" \
+ EX_TABLE(0b,3b) EX_TABLE(1b,3b) \
+ : [rc] "=&d" (__rc), [_to] "+Q" (*(to)) \
+ : [_size] "d" (size), [_from] "Q" (*(from)), \
+ [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,
- (unsigned char *)x,
- size, "llilh");
+ rc = __put_user_asm((unsigned char __user *)ptr,
+ (unsigned char *)x,
+ size);
break;
case 2:
- rc = __put_get_user_asm((unsigned short __user *)ptr,
- (unsigned short *)x,
- size, "llilh");
+ rc = __put_user_asm((unsigned short __user *)ptr,
+ (unsigned short *)x,
+ size);
break;
case 4:
- rc = __put_get_user_asm((unsigned int __user *)ptr,
- (unsigned int *)x,
- size, "llilh");
+ rc = __put_user_asm((unsigned int __user *)ptr,
+ (unsigned int *)x,
+ size);
break;
case 8:
- rc = __put_get_user_asm((unsigned long __user *)ptr,
- (unsigned long *)x,
- size, "llilh");
+ rc = __put_user_asm((unsigned long __user *)ptr,
+ (unsigned long *)x,
+ 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,
- (unsigned char __user *)ptr,
- size, "lghi");
+ rc = __get_user_asm((unsigned char *)x,
+ (unsigned char __user *)ptr,
+ size);
break;
case 2:
- rc = __put_get_user_asm((unsigned short *)x,
- (unsigned short __user *)ptr,
- size, "lghi");
+ rc = __get_user_asm((unsigned short *)x,
+ (unsigned short __user *)ptr,
+ size);
break;
case 4:
- rc = __put_get_user_asm((unsigned int *)x,
- (unsigned int __user *)ptr,
- size, "lghi");
+ rc = __get_user_asm((unsigned int *)x,
+ (unsigned int __user *)ptr,
+ size);
break;
case 8:
- rc = __put_get_user_asm((unsigned long *)x,
- (unsigned long __user *)ptr,
- size, "lghi");
+ rc = __get_user_asm((unsigned long *)x,
+ (unsigned long __user *)ptr,
+ size);
break;
default:
__get_user_bad();
diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index a596e69d3c47..d3a700385875 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;
}
--
2.32.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] s390/uaccess: introduce bit field for OAC specifier
2022-01-11 10:00 [PATCH] s390/uaccess: introduce bit field for OAC specifier Janis Schoetterl-Glausch
@ 2022-01-14 13:58 ` Heiko Carstens
0 siblings, 0 replies; 2+ messages in thread
From: Heiko Carstens @ 2022-01-14 13:58 UTC (permalink / raw)
To: Janis Schoetterl-Glausch
Cc: Vasily Gorbik, Christian Borntraeger, Sven Schnelle, Nico Boehr,
Alexander Gordeev, linux-s390, linux-kernel
On Tue, Jan 11, 2022 at 11:00:03AM +0100, Janis Schoetterl-Glausch wrote:
> From: Nico Boehr <nrb@linux.ibm.com>
>
> 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>
> ---
> arch/s390/include/asm/uaccess.h | 120 ++++++++++++++++++++------------
> arch/s390/lib/uaccess.c | 24 +++++--
> 2 files changed, 95 insertions(+), 49 deletions(-)
Applied with a couple of indentation + whitespace fixes.
Thanks!
^ permalink raw reply [flat|nested] 2+ messages in thread
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