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Message-ID: <166a5360-8862-b0ef-3ac9-6c73f1f26bbb@linux.ibm.com>
Date: Tue, 8 Feb 2022 14:16:46 +0100
From: Christian Borntraeger <borntraeger@...ux.ibm.com>
To: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Jonathan Corbet <corbet@....net>, kvm@...r.kernel.org,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-s390@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
Sven Schnelle <svens@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>
Subject: Re: [PATCH v2 01/11] s390/uaccess: Add copy_from/to_user_key
functions
Am 08.02.22 um 13:31 schrieb Christian Borntraeger:
> Am 07.02.22 um 17:59 schrieb Janis Schoetterl-Glausch:
>> Add copy_from/to_user_key functions, which perform storage key checking.
>> These functions can be used by KVM for emulating instructions that need
>> to be key checked.
>> These functions differ from their non _key counterparts in
>> include/linux/uaccess.h only in the additional key argument and must be
>> kept in sync with those.
>>
>> Since the existing uaccess implementation on s390 makes use of move
>> instructions that support having an additional access key supplied,
>> we can implement raw_copy_from/to_user_key by enhancing the
>> existing implementation.
>>
>> Signed-off-by: Janis Schoetterl-Glausch <scgl@...ux.ibm.com>
>
> Reviewed-by: Christian Borntraeger <borntraeger@...ibm.com>
please use
Reviewed-by: Christian Borntraeger <borntraeger@...ux.ibm.com>
instead...
>
>> ---
>> arch/s390/include/asm/uaccess.h | 22 +++++++++
>> arch/s390/lib/uaccess.c | 81 +++++++++++++++++++++++++--------
>> 2 files changed, 85 insertions(+), 18 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
>> index d74e26b48604..ba1bcb91af95 100644
>> --- a/arch/s390/include/asm/uaccess.h
>> +++ b/arch/s390/include/asm/uaccess.h
>> @@ -44,6 +44,28 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n);
>> #define INLINE_COPY_TO_USER
>> #endif
>> +unsigned long __must_check
>> +_copy_from_user_key(void *to, const void __user *from, unsigned long n, unsigned long key);
>> +
>> +static __always_inline unsigned long __must_check
>> +copy_from_user_key(void *to, const void __user *from, unsigned long n, unsigned long key)
>> +{
>> + if (likely(check_copy_size(to, n, false)))
>> + n = _copy_from_user_key(to, from, n, key);
>> + return n;
>> +}
>> +
>> +unsigned long __must_check
>> +_copy_to_user_key(void __user *to, const void *from, unsigned long n, unsigned long key);
>> +
>> +static __always_inline unsigned long __must_check
>> +copy_to_user_key(void __user *to, const void *from, unsigned long n, unsigned long key)
>> +{
>> + if (likely(check_copy_size(from, n, true)))
>> + n = _copy_to_user_key(to, from, n, key);
>> + return n;
>> +}
>> +
>> int __put_user_bad(void) __attribute__((noreturn));
>> int __get_user_bad(void) __attribute__((noreturn));
>> diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
>> index 8a5d21461889..b709239feb5d 100644
>> --- a/arch/s390/lib/uaccess.c
>> +++ b/arch/s390/lib/uaccess.c
>> @@ -59,11 +59,13 @@ static inline int copy_with_mvcos(void)
>> #endif
>> static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
>> - unsigned long size)
>> + unsigned long size, unsigned long key)
>> {
>> unsigned long tmp1, tmp2;
>> union oac spec = {
>> + .oac2.key = key,
>> .oac2.as = PSW_BITS_AS_SECONDARY,
>> + .oac2.k = 1,
>> .oac2.a = 1,
>> };
>> @@ -94,19 +96,19 @@ static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr
>> }
>> static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
>> - unsigned long size)
>> + unsigned long size, unsigned long key)
>> {
>> unsigned long tmp1, tmp2;
>> tmp1 = -256UL;
>> asm volatile(
>> " sacf 0\n"
>> - "0: mvcp 0(%0,%2),0(%1),%3\n"
>> + "0: mvcp 0(%0,%2),0(%1),%[key]\n"
>> "7: jz 5f\n"
>> "1: algr %0,%3\n"
>> " la %1,256(%1)\n"
>> " la %2,256(%2)\n"
>> - "2: mvcp 0(%0,%2),0(%1),%3\n"
>> + "2: mvcp 0(%0,%2),0(%1),%[key]\n"
>> "8: jnz 1b\n"
>> " j 5f\n"
>> "3: la %4,255(%1)\n" /* %4 = ptr + 255 */
>> @@ -115,7 +117,7 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
>> " slgr %4,%1\n"
>> " clgr %0,%4\n" /* copy crosses next page boundary? */
>> " jnh 6f\n"
>> - "4: mvcp 0(%4,%2),0(%1),%3\n"
>> + "4: mvcp 0(%4,%2),0(%1),%[key]\n"
>> "9: slgr %0,%4\n"
>> " j 6f\n"
>> "5: slgr %0,%0\n"
>> @@ -123,24 +125,49 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
>> EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
>> EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
>> : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
>> - : : "cc", "memory");
>> + : [key] "d" (key << 4)
>> + : "cc", "memory");
>> return size;
>> }
>> -unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
>> +static unsigned long raw_copy_from_user_key(void *to, const void __user *from,
>> + unsigned long n, unsigned long key)
>> {
>> if (copy_with_mvcos())
>> - return copy_from_user_mvcos(to, from, n);
>> - return copy_from_user_mvcp(to, from, n);
>> + return copy_from_user_mvcos(to, from, n, key);
>> + return copy_from_user_mvcp(to, from, n, key);
>> +}
>> +
>> +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);
>> }
>> EXPORT_SYMBOL(raw_copy_from_user);
>> +unsigned long _copy_from_user_key(void *to, const void __user *from,
>> + unsigned long n, unsigned long key)
>> +{
>> + unsigned long res = n;
>> +
>> + might_fault();
>> + if (!should_fail_usercopy()) {
>> + instrument_copy_from_user(to, from, n);
>> + res = raw_copy_from_user_key(to, from, n, key);
>> + }
>> + if (unlikely(res))
>> + memset(to + (n - res), 0, res);
>> + return res;
>> +}
>> +EXPORT_SYMBOL(_copy_from_user_key);
>> +
>> static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
>> - unsigned long size)
>> + unsigned long size, unsigned long key)
>> {
>> unsigned long tmp1, tmp2;
>> union oac spec = {
>> + .oac1.key = key,
>> .oac1.as = PSW_BITS_AS_SECONDARY,
>> + .oac1.k = 1,
>> .oac1.a = 1,
>> };
>> @@ -171,19 +198,19 @@ static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x,
>> }
>> static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
>> - unsigned long size)
>> + unsigned long size, unsigned long key)
>> {
>> unsigned long tmp1, tmp2;
>> tmp1 = -256UL;
>> asm volatile(
>> " sacf 0\n"
>> - "0: mvcs 0(%0,%1),0(%2),%3\n"
>> + "0: mvcs 0(%0,%1),0(%2),%[key]\n"
>> "7: jz 5f\n"
>> "1: algr %0,%3\n"
>> " la %1,256(%1)\n"
>> " la %2,256(%2)\n"
>> - "2: mvcs 0(%0,%1),0(%2),%3\n"
>> + "2: mvcs 0(%0,%1),0(%2),%[key]\n"
>> "8: jnz 1b\n"
>> " j 5f\n"
>> "3: la %4,255(%1)\n" /* %4 = ptr + 255 */
>> @@ -192,7 +219,7 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
>> " slgr %4,%1\n"
>> " clgr %0,%4\n" /* copy crosses next page boundary? */
>> " jnh 6f\n"
>> - "4: mvcs 0(%4,%1),0(%2),%3\n"
>> + "4: mvcs 0(%4,%1),0(%2),%[key]\n"
>> "9: slgr %0,%4\n"
>> " j 6f\n"
>> "5: slgr %0,%0\n"
>> @@ -200,18 +227,36 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
>> EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
>> EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
>> : "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
>> - : : "cc", "memory");
>> + : [key] "d" (key << 4)
>> + : "cc", "memory");
>> return size;
>> }
>> -unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
>> +static unsigned long raw_copy_to_user_key(void __user *to, const void *from,
>> + unsigned long n, unsigned long key)
>> {
>> if (copy_with_mvcos())
>> - return copy_to_user_mvcos(to, from, n);
>> - return copy_to_user_mvcs(to, from, n);
>> + return copy_to_user_mvcos(to, from, n, key);
>> + return copy_to_user_mvcs(to, from, n, key);
>> +}
>> +
>> +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);
>> }
>> EXPORT_SYMBOL(raw_copy_to_user);
>> +unsigned long _copy_to_user_key(void __user *to, const void *from,
>> + unsigned long n, unsigned long key)
>> +{
>> + might_fault();
>> + if (should_fail_usercopy())
>> + return n;
>> + instrument_copy_to_user(to, from, n);
>> + return raw_copy_to_user_key(to, from, n, key);
>> +}
>> +EXPORT_SYMBOL(_copy_to_user_key);
>> +
>> static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size)
>> {
>> unsigned long tmp1, tmp2;
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