You were heading towards:
ld: undefined __mcsafe_copy
since that is also inside the #ifdef.
Weren't you going to "select" this?
I'm seriously wondering whether the ifdef still makes sense. Now I don't have an extra exception table and routines to sort/search/fixup, it doesn't seem as useful as it was a few iterations ago.
Sent from my iPhone
> On Jan 5, 2016, at 20:43, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
>> 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;
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