diff options
| -rw-r--r-- | arch/x86/include/asm/uaccess_64.h | 3 | ||||
| -rw-r--r-- | arch/x86/lib/memcpy_64.S | 14 | ||||
| -rw-r--r-- | arch/x86/lib/usercopy_64.c | 21 |
3 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h index 62546b3a398eb..c63efc07891f1 100644 --- a/arch/x86/include/asm/uaccess_64.h +++ b/arch/x86/include/asm/uaccess_64.h @@ -194,4 +194,7 @@ __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) unsigned long copy_user_handle_tail(char *to, char *from, unsigned len); +unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len); + #endif /* _ASM_X86_UACCESS_64_H */ diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index f01a88391c98d..c3b527a9f95d9 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -265,9 +265,23 @@ EXPORT_SYMBOL_GPL(__memcpy_mcsafe) mov %ecx, %eax ret + /* + * For write fault handling, given the destination is unaligned, + * we handle faults on multi-byte writes with a byte-by-byte + * copy up to the write-protected page. + */ +.E_write_words: + shll $3, %ecx + addl %edx, %ecx + movl %ecx, %edx + jmp mcsafe_handle_tail + .previous _ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes) _ASM_EXTABLE_FAULT(.L_read_words, .E_read_words) _ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes) + _ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes) + _ASM_EXTABLE(.L_write_words, .E_write_words) + _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) #endif diff --git a/arch/x86/lib/usercopy_64.c b/arch/x86/lib/usercopy_64.c index 75d3776123cc0..7ebc9901dd059 100644 --- a/arch/x86/lib/usercopy_64.c +++ b/arch/x86/lib/usercopy_64.c @@ -75,6 +75,27 @@ copy_user_handle_tail(char *to, char *from, unsigned len) return len; } +/* + * Similar to copy_user_handle_tail, probe for the write fault point, + * but reuse __memcpy_mcsafe in case a new read error is encountered. + * clac() is handled in _copy_to_iter_mcsafe(). + */ +__visible unsigned long +mcsafe_handle_tail(char *to, char *from, unsigned len) +{ + for (; len; --len, to++, from++) { + /* + * Call the assembly routine back directly since + * memcpy_mcsafe() may silently fallback to memcpy. + */ + unsigned long rem = __memcpy_mcsafe(to, from, 1); + + if (rem) + break; + } + return len; +} + #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE /** * clean_cache_range - write back a cache range with CLWB |