在 2025/2/13 1:18, Catalin Marinas 写道:
On Mon, Dec 09, 2024 at 10:42:57AM +0800, Tong Tiangen wrote:
The copy_mc_to_kernel() helper is memory copy implementation that handles
source exceptions. It can be used in memory copy scenarios that tolerate
hardware memory errors(e.g: pmem_read/dax_copy_to_iter).
Currently, only x86 and ppc support this helper, Add this for ARM64 as
well, if ARCH_HAS_COPY_MC is defined, by implementing copy_mc_to_kernel()
and memcpy_mc() functions.
Because there is no caller-saved GPR is available for saving "bytes not
copied" in memcpy(), the memcpy_mc() is referenced to the implementation
of copy_from_user(). In addition, the fixup of MOPS insn is not considered
at present.
Same question as on the previous patch, can we not avoid the memcpy()
duplication if the only difference is entries in the exception table?
IIUC in patch 2 fixup_exception() even ignores the new type. The error
must come on the do_sea() path.
As I said in commit message, it is not normalized with the memcpy()
because of the lack of GPR. If there is no GPR shortage problem, we can
extract the common code of memcpy_mc() and memcpy()，The unextracted
code is using different exception table entries.
Thanks,
Tong.
