This series is initially targeted at the folks doing filesystems
on top of NVDIMMs. They really want to be able to return -EIO
when there is a h/w error (just like spinning rust, and SSD does).
I plan to use the same infrastructure in parts 1&2 to write a
machine check aware "copy_from_user()" that will SIGBUS the
calling application when a syscall touches poison in user space
(just like we do when the application touches the poison itself).
Changes V2-V3:
Andy: Don't hack "regs->ax = BIT(63) | addr;" in the machine check
handler. Now have better fixup code that computes the number
of remaining bytes (just like page-fault fixup).
Andy: #define for BIT(63). Done, plus couple of extra macros using it.
Boris: Don't clutter up generic code (like mm/extable.c) with this.
I moved everything under arch/x86 (the asm-generic change is
a more generic #define).
Boris: Dependencies for CONFIG_MCE_KERNEL_RECOVERY are too generic.
I made it a real menu item with default "n". Dan Williams
will use "select MCE_KERNEL_RECOVERY" from his persistent
filesystem code.
Boris: Simplify conditionals in mce.c by moving tolerant/kill_it
checks earlier, with a skip to end if they aren't set.
Boris: Miscellaneous grammar/punctuation. Fixed.
Boris: Don't leak spurious __start_mcextable symbols into kernels
that didn't configure MCE_KERNEL_RECOVERY. Done.
Tony: New code doesn't belong in user_copy_64.S/uaccess*.h. Moved
to new .S/.h files
Elliott:Cacheing behavior non-optimal. Could use movntdqa, vmovntdqa
or vmovntdqa on source addresses. I didn't fix this yet. Think
of the current mcsafe_memcpy() as the first of several functions.
This one is useful for small copies (meta-data) where the overhead
of saving SSE/AVX state isn't justified.
Changes V1->V2:
0-day: Reported build errors and warnings on 32-bit systems. Fixed
0-day: Reported bloat to tinyconfig. Fixed
Boris: Suggestions to use extra macros to reduce code duplication in
_ASM_*EXTABLE. Done
Boris: Re-write "tolerant==3" check to reduce indentation level. See below.
Andy: Check IP is valid before searching kernel exception tables. Done.
Andy: Explain use of BIT(63) on return value from mcsafe_memcpy(). Done
(added decode macros).
Andy: Untangle mess of code in tail of do_machine_check() to make it
clear what is going on (e.g. that we only enter the
ist_begin_non_atomic()
if we were called from user code, not from kernel!). Done.
Tony Luck (3):
x86, ras: Add new infrastructure for machine check fixup tables
x86, ras: Extend machine check recovery code to annotated ring0 areas
x86, ras: Add mcsafe_memcpy() function to recover from machine checks
arch/x86/Kconfig | 10 +++
arch/x86/include/asm/asm.h | 10 ++-
arch/x86/include/asm/mce.h | 14 +++
arch/x86/include/asm/mcsafe_copy.h | 11 +++
arch/x86/kernel/cpu/mcheck/mce-severity.c | 21 ++++-
arch/x86/kernel/cpu/mcheck/mce.c | 86 +++++++++++-------
arch/x86/kernel/vmlinux.lds.S | 6 +-
arch/x86/kernel/x8664_ksyms_64.c | 5 ++
arch/x86/lib/Makefile | 1 +
arch/x86/lib/mcsafe_copy.S | 142 ++++++++++++++++++++++++++++++
arch/x86/mm/extable.c | 19 ++++
include/asm-generic/vmlinux.lds.h | 12 +--
12 files changed, 293 insertions(+), 44 deletions(-)
create mode 100644 arch/x86/include/asm/mcsafe_copy.h
create mode 100644 arch/x86/lib/mcsafe_copy.S
--
2.1.4
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