On Thu, Dec 10, 2015 at 01:58:04PM -0800, Tony Luck wrote:
> Copy the existing page fault fixup mechanisms to create a new table
> to be used when fixing machine checks. Note:
> 1) At this time we only provide a macro to annotate assembly code
> 2) We assume all fixups will in code builtin to the kernel.
> 3) Only for x86_64
> 4) New code under CONFIG_MCE_KERNEL_RECOVERY
>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
> arch/x86/Kconfig | 4 ++++
> arch/x86/include/asm/asm.h | 10 ++++++++--
> arch/x86/include/asm/uaccess.h | 8 ++++++++
> arch/x86/mm/extable.c | 19 +++++++++++++++++++
> include/asm-generic/vmlinux.lds.h | 6 ++++++
> include/linux/module.h | 1 +
> kernel/extable.c | 20 ++++++++++++++++++++
> 7 files changed, 66 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 96d058a87100..db5c6e1d6e37 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1001,6 +1001,10 @@ 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
> + depends on X86_MCE && X86_64
> + def_bool y
Shouldn't that depend on NVDIMM or whatnot? Looks too generic now.
> +
> config X86_THERMAL_VECTOR
> def_bool y
> depends on X86_MCE_INTEL
> diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
> index 189679aba703..a5d483ac11fa 100644
> --- a/arch/x86/include/asm/asm.h
> +++ b/arch/x86/include/asm/asm.h
> @@ -44,13 +44,19 @@
>
> /* Exception table entry */
> #ifdef __ASSEMBLY__
> -# define _ASM_EXTABLE(from,to) \
> - .pushsection "__ex_table","a" ; \
> +# define __ASM_EXTABLE(from, to, table) \
> + .pushsection table, "a" ; \
> .balign 8 ; \
> .long (from) - . ; \
> .long (to) - . ; \
> .popsection
>
> +# define _ASM_EXTABLE(from, to) \
> + __ASM_EXTABLE(from, to, "__ex_table")
> +
> +# define _ASM_MCEXTABLE(from, to) \
> + __ASM_EXTABLE(from, to, "__mcex_table")
> +
> # define _ASM_EXTABLE_EX(from,to) \
> .pushsection "__ex_table","a" ; \
> .balign 8 ; \
> diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> index a8df874f3e88..7b02ca1991b4 100644
> --- a/arch/x86/include/asm/uaccess.h
> +++ b/arch/x86/include/asm/uaccess.h
> @@ -111,6 +111,14 @@ struct exception_table_entry {
> #define ARCH_HAS_SEARCH_EXTABLE
>
> extern int fixup_exception(struct pt_regs *regs);
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> +extern int fixup_mcexception(struct pt_regs *regs, u64 addr);
> +#else
> +static inline int fixup_mcexception(struct pt_regs *regs, u64 addr)
> +{
> + return 0;
> +}
> +#endif
> extern int early_fixup_exception(unsigned long *ip);
No need for "extern"
>
> /*
> diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
> index 903ec1e9c326..a461c4212758 100644
> --- a/arch/x86/mm/extable.c
> +++ b/arch/x86/mm/extable.c
> @@ -49,6 +49,25 @@ int fixup_exception(struct pt_regs *regs)
> return 0;
> }
>
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> +int fixup_mcexception(struct pt_regs *regs, u64 addr)
> +{
If you move the #ifdef here, you can save yourself the ifdeffery in the
header above.
> + const struct exception_table_entry *fixup;
> + unsigned long new_ip;
> +
> + fixup = search_mcexception_tables(regs->ip);
> + if (fixup) {
> + new_ip = ex_fixup_addr(fixup);
> +
> + regs->ip = new_ip;
> + regs->ax = BIT(63) | addr;
> + return 1;
> + }
> +
> + return 0;
> +}
> +#endif
> +
> /* Restricted version used during very early boot */
> int __init early_fixup_exception(unsigned long *ip)
> {
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 1781e54ea6d3..21bb20d1172a 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -473,6 +473,12 @@
> VMLINUX_SYMBOL(__start___ex_table) = .; \
> *(__ex_table) \
> VMLINUX_SYMBOL(__stop___ex_table) = .; \
> + } \
> + . = ALIGN(align); \
> + __mcex_table : AT(ADDR(__mcex_table) - LOAD_OFFSET) { \
> + VMLINUX_SYMBOL(__start___mcex_table) = .; \
> + *(__mcex_table) \
> + VMLINUX_SYMBOL(__stop___mcex_table) = .; \
Of all the places, this one is missing #ifdef CONFIG_MCE_KERNEL_RECOVERY.
> }
>
> /*
> diff --git a/include/linux/module.h b/include/linux/module.h
> index 3a19c79918e0..ffecbfcc462c 100644
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -270,6 +270,7 @@ extern const typeof(name) __mod_##type##__##name##_device_table \
>
> /* Given an address, look for it in the exception tables */
> const struct exception_table_entry *search_exception_tables(unsigned long add);
> +const struct exception_table_entry *search_mcexception_tables(unsigned long a);
>
> struct notifier_block;
>
> diff --git a/kernel/extable.c b/kernel/extable.c
> index e820ccee9846..7b224fbcb708 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -34,6 +34,10 @@ DEFINE_MUTEX(text_mutex);
>
> extern struct exception_table_entry __start___ex_table[];
> extern struct exception_table_entry __stop___ex_table[];
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> +extern struct exception_table_entry __start___mcex_table[];
> +extern struct exception_table_entry __stop___mcex_table[];
> +#endif
>
> /* Cleared by build time tools if the table is already sorted. */
> u32 __initdata __visible main_extable_sort_needed = 1;
> @@ -45,6 +49,10 @@ void __init sort_main_extable(void)
> pr_notice("Sorting __ex_table...\n");
> sort_extable(__start___ex_table, __stop___ex_table);
> }
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> + if (__stop___mcex_table > __start___mcex_table)
> + sort_extable(__start___mcex_table, __stop___mcex_table);
> +#endif
> }
>
> /* Given an address, look for it in the exception tables. */
> @@ -58,6 +66,18 @@ const struct exception_table_entry *search_exception_tables(unsigned long addr)
> return e;
> }
>
> +#ifdef CONFIG_MCE_KERNEL_RECOVERY
> +/* Given an address, look for it in the machine check exception tables. */
> +const struct exception_table_entry *search_mcexception_tables(
> + unsigned long addr)
> +{
> + const struct exception_table_entry *e;
> +
> + e = search_extable(__start___mcex_table, __stop___mcex_table-1, addr);
> + return e;
> +}
> +#endif
You can make this one a bit more readable by doing:
/* Given an address, look for it in the machine check exception tables. */
const struct exception_table_entry *
search_mcexception_tables(unsigned long addr)
{
#ifdef CONFIG_MCE_KERNEL_RECOVERY
return search_extable(__start___mcex_table,
__stop___mcex_table - 1, addr);
#endif
}
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
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