Messages in this thread Patch in this message | | | From | Janis Schoetterl-Glausch <> | Subject | [RFC PATCH 2/2] s390/uaccess: Provide raw_copy_from/to_user_opaque | Date | Thu, 3 Feb 2022 19:11:41 +0100 |
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This enables KVM to perform key checked guest accesses by passing the access key via the opaque argument of __copy_from/to_user_opaque. 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_opaque by enhancing the existing implementation.
Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com> --- arch/s390/include/asm/uaccess.h | 27 ++++++++++++++-- arch/s390/lib/uaccess.c | 56 ++++++++++++++++++++------------- 2 files changed, 60 insertions(+), 23 deletions(-)
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h index 02b467461163..1a324bc3ae0b 100644 --- a/arch/s390/include/asm/uaccess.h +++ b/arch/s390/include/asm/uaccess.h @@ -33,11 +33,34 @@ static inline int __range_ok(unsigned long addr, unsigned long size) #define access_ok(addr, size) __access_ok(addr, size) +#define uaccess_opaque uaccess_opaque +struct uaccess_opaque { + u8 key; +}; + unsigned long __must_check -raw_copy_from_user(void *to, const void __user *from, unsigned long n); +raw_copy_from_user_opaque(void *to, const void __user *from, unsigned long n, + struct uaccess_opaque opaque); unsigned long __must_check -raw_copy_to_user(void __user *to, const void *from, unsigned long n); +raw_copy_to_user_opaque(void __user *to, const void *from, unsigned long n, + struct uaccess_opaque opaque); + +static __always_inline unsigned long __must_check +raw_copy_from_user(void *to, const void __user *from, unsigned long n) +{ + struct uaccess_opaque opaque = { .key = 0}; + + return raw_copy_from_user_opaque(to, from, n, opaque); +} + +static __always_inline unsigned long __must_check +raw_copy_to_user(void __user *to, const void *from, unsigned long n) +{ + struct uaccess_opaque opaque = { .key = 0}; + + return raw_copy_to_user_opaque(to, from, n, opaque); +} #ifndef CONFIG_KASAN #define INLINE_COPY_FROM_USER diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c index d3a700385875..6446634c3b75 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, u8 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, u8 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 +125,31 @@ 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) +unsigned long raw_copy_from_user_opaque(void *to, const void __user *from, + unsigned long n, + struct uaccess_opaque opaque) { + u8 key = opaque.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); } -EXPORT_SYMBOL(raw_copy_from_user); +EXPORT_SYMBOL(raw_copy_from_user_opaque); -static inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x, - unsigned long size) +inline unsigned long copy_to_user_mvcos(void __user *ptr, const void *x, + unsigned long size, u8 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 +180,19 @@ 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, u8 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 +201,7 @@ 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" @@ -200,17 +209,22 @@ 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) +unsigned long raw_copy_to_user_opaque(void __user *to, const void *from, + unsigned long n, + struct uaccess_opaque opaque) { + u8 key = opaque.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); } -EXPORT_SYMBOL(raw_copy_to_user); +EXPORT_SYMBOL(raw_copy_to_user_opaque); static inline unsigned long clear_user_mvcos(void __user *to, unsigned long size) { -- 2.32.0
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