In preparation for using memcpy_mcsafe() to handle user copies it needs to be to handle write-protection faults while writing user pages. Add MMU-fault handlers alongside the machine-check exception handlers.
Note that the machine check fault exception handling makes assumptions about source buffer alignment and poison alignment. In the write fault case, given the destination buffer is arbitrarily aligned, it needs a separate / additional fault handling approach. The mcsafe_handle_tail() helper is reused. The @limit argument is set to @len since there is no safety concern about retriggering an MMU fault, and this simplifies the assembly. Cc: <x...@kernel.org> Cc: Ingo Molnar <mi...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: Tony Luck <tony.l...@intel.com> Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Linus Torvalds <torva...@linux-foundation.org> Co-developed-by: Tony Luck <tony.l...@intel.com> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> --- arch/x86/lib/memcpy_64.S | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index 97b772fcf62f..fc9c1f594c71 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -345,6 +345,16 @@ EXPORT_SYMBOL_GPL(memcpy_mcsafe_unrolled) mov %ecx, %eax ret +.E_write_cache_X: + shll $6, %ecx + jmp .E_handle_tail +.E_write_trailing_words: + shll $3, %ecx +.E_handle_tail: + addl %edx, %ecx + movl %ecx, %edx + jmp mcsafe_handle_tail + .previous _ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes) @@ -358,4 +368,15 @@ EXPORT_SYMBOL_GPL(memcpy_mcsafe_unrolled) _ASM_EXTABLE_FAULT(.L_cache_r7, .E_cache_7) _ASM_EXTABLE_FAULT(.L_read_trailing_words, .E_trailing_words) _ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes) + _ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes) + _ASM_EXTABLE(.L_cache_w0, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w1, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w2, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w3, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w4, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w5, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w6, .E_write_cache_X) + _ASM_EXTABLE(.L_cache_w7, .E_write_cache_X) + _ASM_EXTABLE(.L_write_trailing_words, .E_write_trailing_words) + _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) #endif _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm