[PATCH v11 0/5]arm64: add ARCH_HAS_COPY_MC support
Tong Tiangen
tongtiangen at huawei.com
Sat Feb 17 23:05:51 PST 2024
Hi Mark:
Kindly ping :)
Thanks.
Tong.
在 2024/2/7 21:21, Tong Tiangen 写道:
> With the increase of memory capacity and density, the probability of memory
> error also increases. The increasing size and density of server RAM in data
> centers and clouds have shown increased uncorrectable memory errors.
>
> Currently, more and more scenarios that can tolerate memory errors，such as
> CoW[1,2], KSM copy[3], coredump copy[4], khugepaged[5,6], uaccess copy[7],
> etc.
>
> This patchset introduces a new processing framework on ARM64, which enables
> ARM64 to support error recovery in the above scenarios, and more scenarios
> can be expanded based on this in the future.
>
> In arm64, memory error handling in do_sea(), which is divided into two cases:
> 1. If the user state consumed the memory errors, the solution is to kill
> the user process and isolate the error page.
> 2. If the kernel state consumed the memory errors, the solution is to
> panic.
>
> For case 2, Undifferentiated panic may not be the optimal choice, as it can
> be handled better. In some scenarios, we can avoid panic, such as uaccess,
> if the uaccess fails due to memory error, only the user process will be
> affected, killing the user process and isolating the user page with
> hardware memory errors is a better choice.
>
> [1] commit d302c2398ba2 ("mm, hwpoison: when copy-on-write hits poison, take page offline")
> [2] commit 1cb9dc4b475c ("mm: hwpoison: support recovery from HugePage copy-on-write faults")
> [3] commit 6b970599e807 ("mm: hwpoison: support recovery from ksm_might_need_to_copy()")
> [4] commit 245f09226893 ("mm: hwpoison: coredump: support recovery from dump_user_range()")
> [5] commit 98c76c9f1ef7 ("mm/khugepaged: recover from poisoned anonymous memory")
> [6] commit 12904d953364 ("mm/khugepaged: recover from poisoned file-backed memory")
> [7] commit 278b917f8cb9 ("x86/mce: Add _ASM_EXTABLE_CPY for copy user access")
>
> ------------------
> Test result:
>
> 1. copy_page(), copy_mc_page() basic function test pass, and the disassembly
> contents remains the same before and after refactor.
>
> 2. copy_to/from_user() access kernel NULL pointer raise translation fault
> and dump error message then die(), test pass.
>
> 3. Test following scenarios: copy_from_user(), get_user(), COW.
>
> Before patched: trigger a hardware memory error then panic.
> After patched: trigger a hardware memory error without panic.
>
> Testing step:
> step1. start an user-process.
> step2. poison(einj) the user-process's page.
> step3: user-process access the poison page in kernel mode, then trigger SEA.
> step4: the kernel will not panic, only the user process is killed, the poison
> page is isolated. (before patched, the kernel will panic in do_sea())
>
> ------------------
>
> Since V10:
> Accroding Mark's suggestion:
> 1. Merge V10's patch2 and patch3 to V11's patch2.
> 2. Patch2(V11): use new fixup_type for ld* in copy_to_user(), fix fatal
> issues (NULL kernel pointeraccess) been fixup incorrectly.
> 3. Patch2(V11): refactoring the logic of do_sea().
> 4. Patch4(V11): Remove duplicate assembly logic and remove do_mte().
>
> Besides:
> 1. Patch2(V11): remove st* insn's fixup, st* generally not trigger memory error.
> 2. Split a part of the logic of patch2(V11) to patch5(V11), for detail,
> see patch5(V11)'s commit msg.
> 3. Remove patch6(v10) “arm64: introduce copy_mc_to_kernel() implementation”.
> During modification, some problems that cannot be solved in a short
> period are found. The patch will be released after the problems are
> solved.
> 4. Add test result in this patch.
> 5. Modify patchset title, do not use machine check and remove "-next".
>
> Since V9:
> 1. Rebase to latest kernel version 6.8-rc2.
> 2. Add patch 6/6 to support copy_mc_to_kernel().
>
> Since V8:
> 1. Rebase to latest kernel version and fix topo in some of the patches.
> 2. According to the suggestion of Catalin, I attempted to modify the
> return value of function copy_mc_[user]_highpage() to bytes not copied.
> During the modification process, I found that it would be more
> reasonable to return -EFAULT when copy error occurs (referring to the
> newly added patch 4).
>
> For ARM64, the implementation of copy_mc_[user]_highpage() needs to
> consider MTE. Considering the scenario where data copying is successful
> but the MTE tag copying fails, it is also not reasonable to return
> bytes not copied.
> 3. Considering the recent addition of machine check safe support for
> multiple scenarios, modify commit message for patch 5 (patch 4 for V8).
>
> Since V7:
> Currently, there are patches supporting recover from poison
> consumption for the cow scenario[1]. Therefore, Supporting cow
> scenario under the arm64 architecture only needs to modify the relevant
> code under the arch/.
> [1]https://lore.kernel.org/lkml/20221031201029.102123-1-tony.luck@intel.com/
>
> Since V6:
> Resend patches that are not merged into the mainline in V6.
>
> Since V5:
> 1. Add patch2/3 to add uaccess assembly helpers.
> 2. Optimize the implementation logic of arm64_do_kernel_sea() in patch8.
> 3. Remove kernel access fixup in patch9.
> All suggestion are from Mark.
>
> Since V4:
> 1. According Michael's suggestion, add patch5.
> 2. According Mark's suggestiog, do some restructuring to arm64
> extable, then a new adaptation of machine check safe support is made based
> on this.
> 3. According Mark's suggestion, support machine check safe in do_mte() in
> cow scene.
> 4. In V4, two patches have been merged into -next, so V5 not send these
> two patches.
>
> Since V3:
> 1. According to Robin's suggestion, direct modify user_ldst and
> user_ldp in asm-uaccess.h and modify mte.S.
> 2. Add new macro USER_MC in asm-uaccess.h, used in copy_from_user.S
> and copy_to_user.S.
> 3. According to Robin's suggestion, using micro in copy_page_mc.S to
> simplify code.
> 4. According to KeFeng's suggestion, modify powerpc code in patch1.
> 5. According to KeFeng's suggestion, modify mm/extable.c and some code
> optimization.
>
> Since V2:
> 1. According to Mark's suggestion, all uaccess can be recovered due to
> memory error.
> 2. Scenario pagecache reading is also supported as part of uaccess
> (copy_to_user()) and duplication code problem is also solved.
> Thanks for Robin's suggestion.
> 3. According Mark's suggestion, update commit message of patch 2/5.
> 4. According Borisllav's suggestion, update commit message of patch 1/5.
>
> Since V1:
> 1.Consistent with PPC/x86, Using CONFIG_ARCH_HAS_COPY_MC instead of
> ARM64_UCE_KERNEL_RECOVERY.
> 2.Add two new scenes, cow and pagecache reading.
> 3.Fix two small bug(the first two patch).
>
> V1 in here:
> https://lore.kernel.org/lkml/20220323033705.3966643-1-tongtiangen@huawei.com/
>
> Tong Tiangen (5):
> uaccess: add generic fallback version of copy_mc_to_user()
> arm64: add support for ARCH_HAS_COPY_MC
> mm/hwpoison: return -EFAULT when copy fail in
> copy_mc_[user]_highpage()
> arm64: support copy_mc_[user]_highpage()
> arm64: send SIGBUS to user process for SEA exception
>
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/asm-extable.h | 31 ++++++++++++---
> arch/arm64/include/asm/asm-uaccess.h | 4 ++
> arch/arm64/include/asm/extable.h | 1 +
> arch/arm64/include/asm/mte.h | 9 +++++
> arch/arm64/include/asm/page.h | 10 +++++
> arch/arm64/lib/Makefile | 2 +
> arch/arm64/lib/copy_mc_page.S | 37 ++++++++++++++++++
> arch/arm64/lib/copy_page.S | 50 +++----------------------
> arch/arm64/lib/copy_page_template.S | 56 ++++++++++++++++++++++++++++
> arch/arm64/lib/copy_to_user.S | 10 ++---
> arch/arm64/lib/mte.S | 29 ++++++++++++++
> arch/arm64/mm/copypage.c | 45 ++++++++++++++++++++++
> arch/arm64/mm/extable.c | 19 ++++++++++
> arch/arm64/mm/fault.c | 39 ++++++++++++++-----
> arch/powerpc/include/asm/uaccess.h | 1 +
> arch/x86/include/asm/uaccess.h | 1 +
> include/linux/highmem.h | 16 ++++++--
> include/linux/uaccess.h | 9 +++++
> mm/khugepaged.c | 4 +-
> 20 files changed, 304 insertions(+), 70 deletions(-)
> create mode 100644 arch/arm64/lib/copy_mc_page.S
> create mode 100644 arch/arm64/lib/copy_page_template.S
>
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