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s390/uaccess: Separate key uaccess functions 

Implement separate raw_copy_to_user_key() and raw_copy_from_user_key()
functions, which allows to remove the open-coded operand access control
handling from the normal raw_copy_to_user() / raw_copy_from_user()
functions - they are simplified to use immediate instructions to load
hard-coded operand access control values into register zero, which saves
one instruction.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2025-02-11 20:19:27 +01:00 committed by Vasily Gorbik
parent c488f5187a
commit bc6029239c
2 changed files with 92 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

58
arch/s390/include/asm/uaccess.h
View File

@ -22,28 +22,6 @@
void debug_user_asce(int exit);
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;
};
};
#ifdef CONFIG_KMSAN
#define uaccess_kmsan_or_inline noinline __maybe_unused __no_sanitize_memory
#else
@ -51,28 +29,22 @@ union oac {
#endif
static uaccess_kmsan_or_inline __must_check unsigned long
raw_copy_from_user_key(void *to, const void __user *from, unsigned long size, unsigned long key)
raw_copy_from_user(void *to, const void __user *from, unsigned long size)
{
unsigned long osize;
union oac spec = {
.oac2.key = key,
.oac2.as = PSW_BITS_AS_SECONDARY,
.oac2.k = 1,
.oac2.a = 1,
};
int cc;
while (1) {
osize = size;
asm_inline volatile(
" lr %%r0,%[spec]\n"
" lhi %%r0,%[spec]\n"
"0: mvcos %[to],%[from],%[size]\n"
"1: nopr %%r7\n"
CC_IPM(cc)
EX_TABLE_UA_MVCOS_FROM(0b, 0b)
EX_TABLE_UA_MVCOS_FROM(1b, 0b)
: CC_OUT(cc, cc), [size] "+d" (size), [to] "=Q" (*(char *)to)
: [spec] "d" (spec.val), [from] "Q" (*(const char __user *)from)
: [spec] "I" (0x81), [from] "Q" (*(const char __user *)from)
: CC_CLOBBER_LIST("memory", "0"));
if (likely(CC_TRANSFORM(cc) == 0))
return osize - size;
@ -82,35 +54,23 @@ raw_copy_from_user_key(void *to, const void __user *from, unsigned long size, un
}
}
static __always_inline __must_check unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
return raw_copy_from_user_key(to, from, n, 0);
}
static uaccess_kmsan_or_inline __must_check unsigned long
raw_copy_to_user_key(void __user *to, const void *from, unsigned long size, unsigned long key)
raw_copy_to_user(void __user *to, const void *from, unsigned long size)
{
unsigned long osize;
union oac spec = {
.oac1.key = key,
.oac1.as = PSW_BITS_AS_SECONDARY,
.oac1.k = 1,
.oac1.a = 1,
};
int cc;
while (1) {
osize = size;
asm_inline volatile(
" lr %%r0,%[spec]\n"
" llilh %%r0,%[spec]\n"
"0: mvcos %[to],%[from],%[size]\n"
"1: nopr %%r7\n"
CC_IPM(cc)
EX_TABLE_UA_MVCOS_TO(0b, 0b)
EX_TABLE_UA_MVCOS_TO(1b, 0b)
: CC_OUT(cc, cc), [size] "+d" (size), [to] "=Q" (*(char __user *)to)
: [spec] "d" (spec.val), [from] "Q" (*(const char *)from)
: [spec] "I" (0x81), [from] "Q" (*(const char *)from)
: CC_CLOBBER_LIST("memory", "0"));
if (likely(CC_TRANSFORM(cc) == 0))
return osize - size;
@ -120,12 +80,6 @@ raw_copy_to_user_key(void __user *to, const void *from, unsigned long size, unsi
}
}
static __always_inline __must_check unsigned long
raw_copy_to_user(void __user *to, const void *from, unsigned long n)
{
return raw_copy_to_user_key(to, from, n, 0);
}
unsigned long __must_check
_copy_from_user_key(void *to, const void __user *from, unsigned long n, unsigned long key);

86
arch/s390/lib/uaccess.c
View File

@ -31,6 +31,60 @@ void debug_user_asce(int exit)
}
#endif /*CONFIG_DEBUG_ENTRY */
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;
};
};
static uaccess_kmsan_or_inline __must_check unsigned long
raw_copy_from_user_key(void *to, const void __user *from, unsigned long size, unsigned long key)
{
unsigned long osize;
union oac spec = {
.oac2.key = key,
.oac2.as = PSW_BITS_AS_SECONDARY,
.oac2.k = 1,
.oac2.a = 1,
};
int cc;
while (1) {
osize = size;
asm_inline volatile(
" lr %%r0,%[spec]\n"
"0: mvcos %[to],%[from],%[size]\n"
"1: nopr %%r7\n"
CC_IPM(cc)
EX_TABLE_UA_MVCOS_FROM(0b, 0b)
EX_TABLE_UA_MVCOS_FROM(1b, 0b)
: CC_OUT(cc, cc), [size] "+d" (size), [to] "=Q" (*(char *)to)
: [spec] "d" (spec.val), [from] "Q" (*(const char __user *)from)
: CC_CLOBBER_LIST("memory", "0"));
if (CC_TRANSFORM(cc) == 0)
return osize - size;
size -= 4096;
to += 4096;
from += 4096;
}
}
unsigned long _copy_from_user_key(void *to, const void __user *from,
unsigned long n, unsigned long key)
{
@ -48,6 +102,38 @@ unsigned long _copy_from_user_key(void *to, const void __user *from,
}
EXPORT_SYMBOL(_copy_from_user_key);
static uaccess_kmsan_or_inline __must_check unsigned long
raw_copy_to_user_key(void __user *to, const void *from, unsigned long size, unsigned long key)
{
unsigned long osize;
union oac spec = {
.oac1.key = key,
.oac1.as = PSW_BITS_AS_SECONDARY,
.oac1.k = 1,
.oac1.a = 1,
};
int cc;
while (1) {
osize = size;
asm_inline volatile(
" lr %%r0,%[spec]\n"
"0: mvcos %[to],%[from],%[size]\n"
"1: nopr %%r7\n"
CC_IPM(cc)
EX_TABLE_UA_MVCOS_TO(0b, 0b)
EX_TABLE_UA_MVCOS_TO(1b, 0b)
: CC_OUT(cc, cc), [size] "+d" (size), [to] "=Q" (*(char __user *)to)
: [spec] "d" (spec.val), [from] "Q" (*(const char *)from)
: CC_CLOBBER_LIST("memory", "0"));
if (CC_TRANSFORM(cc) == 0)
return osize - size;
size -= 4096;
to += 4096;
from += 4096;
}
}
unsigned long _copy_to_user_key(void __user *to, const void *from,
unsigned long n, unsigned long key)
{