On Thu, Dec 31, 2015 at 11:43 AM, Tony Luck <tony.luck@xxxxxxxxx> wrote:
> Make use of the EXTABLE_FAULT exception table entries. This routine
> returns a structure to indicate the result of the copy:
>
> struct mcsafe_ret {
> u64 trapnr;
> u64 remain;
> };
>
> If the copy is successful, then both 'trapnr' and 'remain' are zero.
>
> If we faulted during the copy, then 'trapnr' will say which type
> of trap (X86_TRAP_PF or X86_TRAP_MC) and 'remain' says how many
> bytes were not copied.
>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
> arch/x86/Kconfig | 10 +++
> arch/x86/include/asm/string_64.h | 10 +++
> arch/x86/kernel/x8664_ksyms_64.c | 4 ++
> arch/x86/lib/memcpy_64.S | 136 +++++++++++++++++++++++++++++++++++++++
> 4 files changed, 160 insertions(+)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 96d058a87100..42d26b4d1ec4 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1001,6 +1001,16 @@ config X86_MCE_INJECT
> If you don't know what a machine check is and you don't do kernel
> QA it is safe to say n.
>
> +config MCE_KERNEL_RECOVERY
> + bool "Recovery from machine checks in special kernel memory copy functions"
> + default n
> + depends on X86_MCE && X86_64
> + ---help---
> + This option provides a new memory copy function mcsafe_memcpy()
> + that is annotated to allow the machine check handler to return
> + to an alternate code path to return an error to the caller instead
> + of crashing the system. Say yes if you have a driver that uses this.
> +
> config X86_THERMAL_VECTOR
> def_bool y
> depends on X86_MCE_INTEL
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index ff8b9a17dc4b..16a8f0e56e4a 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -78,6 +78,16 @@ int strcmp(const char *cs, const char *ct);
> #define memset(s, c, n) __memset(s, c, n)
> #endif
>
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> +struct mcsafe_ret {
> + u64 trapnr;
> + u64 remain;
> +};
Can we move this definition outside of the CONFIG_MCE_KERNEL_RECOVERY
ifdef guard? On a test integration branch the kbuild robot caught the
following:
In file included from include/linux/pmem.h:21:0,
from drivers/acpi/nfit.c:22:
arch/x86/include/asm/pmem.h: In function 'arch_memcpy_from_pmem':
>> arch/x86/include/asm/pmem.h:55:21: error: storage size of 'ret' isn't known
struct mcsafe_ret ret;
^
>> arch/x86/include/asm/pmem.h:57:9: error: implicit declaration of function '__mcsafe_copy' [-Werror=implicit-function-declaration]
ret = __mcsafe_copy(dst, (void __force *) src, n);
^
>> arch/x86/include/asm/pmem.h:55:21: warning: unused variable 'ret' [-Wunused-variable]
struct mcsafe_ret ret;
^
cc1: some warnings being treated as errors
vim +55 arch/x86/include/asm/pmem.h
49 }
50
51 static inline int arch_memcpy_from_pmem(void *dst, const void
__pmem *src,
52 size_t n)
53 {
54 if (IS_ENABLED(CONFIG_MCE_KERNEL_RECOVERY)) {
> 55 struct mcsafe_ret ret;
56
> 57 ret = __mcsafe_copy(dst, (void __force *) src, n);
58 if (ret.remain)
59 return -EIO;
60 return 0;
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>