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SubjectRe: [PATCH 23/43] x86/mm/kaiser: Introduce user-mapped per-cpu areas
On Fri, Nov 24, 2017 at 06:23:51PM +0100, Ingo Molnar wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> These patches are based on work from a team at Graz University of
> Technology posted here: https://github.com/IAIK/KAISER
>
> The KAISER approach keeps two copies of the page tables: one for running
> in the kernel and one for running userspace. But, there are a few
> structures that are needed for switching in and out of the kernel and
> a good subset of *those* are per-cpu data.
>
> This patch creates a new kind of per-cpu data that is mapped and

Never say "This patch" in the commit message of a patch. It is
tautologically useless.

> can be used no matter which copy of the page tables is active.
> Users of this new section will be forthcoming.
>
> Thanks to Hugh Dickins for cleanups to this code.
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: daniel.gruss@iaik.tugraz.at
> Cc: hughd@google.com
> Cc: keescook@google.com
> Cc: linux-mm@kvack.org
> Cc: luto@kernel.org
> Cc: michael.schwarz@iaik.tugraz.at
> Cc: moritz.lipp@iaik.tugraz.at
> Cc: richard.fellner@student.tugraz.at
> Link: https://lkml.kernel.org/r/20171123003444.196CB6DB@viggo.jf.intel.com
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
> include/asm-generic/vmlinux.lds.h | 7 +++++++
> include/linux/percpu-defs.h | 30 ++++++++++++++++++++++++++++++
> 2 files changed, 37 insertions(+)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index bdcd1caae092..e12168936d3f 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -826,7 +826,14 @@
> */
> #define PERCPU_INPUT(cacheline) \
> VMLINUX_SYMBOL(__per_cpu_start) = .; \
> + VMLINUX_SYMBOL(__per_cpu_user_mapped_start) = .; \
> *(.data..percpu..first) \
> + . = ALIGN(cacheline); \
> + *(.data..percpu..user_mapped) \
> + *(.data..percpu..user_mapped..shared_aligned) \
> + . = ALIGN(PAGE_SIZE); \
> + *(.data..percpu..user_mapped..page_aligned) \
> + VMLINUX_SYMBOL(__per_cpu_user_mapped_end) = .; \
> . = ALIGN(PAGE_SIZE); \
> *(.data..percpu..page_aligned) \
> . = ALIGN(cacheline); \
> diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
> index 2d2096ba1cfe..752513674295 100644
> --- a/include/linux/percpu-defs.h
> +++ b/include/linux/percpu-defs.h
> @@ -35,6 +35,12 @@
>
> #endif
>
> +#ifdef CONFIG_KAISER
> +#define USER_MAPPED_SECTION "..user_mapped"
> +#else
> +#define USER_MAPPED_SECTION ""
> +#endif
> /*
> * Base implementations of per-CPU variable declarations and definitions, where
> * the section in which the variable is to be placed is provided by the
> @@ -115,6 +121,12 @@
> #define DEFINE_PER_CPU(type, name) \
> DEFINE_PER_CPU_SECTION(type, name, "")
>
> +#define DECLARE_PER_CPU_USER_MAPPED(type, name) \
> + DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION)
> +
> +#define DEFINE_PER_CPU_USER_MAPPED(type, name) \
> + DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION)
> +
> /*
> * Declaration/definition used for per-CPU variables that must come first in
> * the set of variables.
> @@ -144,6 +156,14 @@
> DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
> ____cacheline_aligned_in_smp
>
> +#define DECLARE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \
> + DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION PER_CPU_SHARED_ALIGNED_SECTION) \
> + ____cacheline_aligned_in_smp
> +
> +#define DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(type, name) \
> + DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION PER_CPU_SHARED_ALIGNED_SECTION) \
> + ____cacheline_aligned_in_smp
> +
> #define DECLARE_PER_CPU_ALIGNED(type, name) \
> DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
> ____cacheline_aligned
> @@ -162,6 +182,16 @@
> #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
> DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
> __aligned(PAGE_SIZE)
> +/*
> + * Declaration/definition used for per-CPU variables that must be page aligned and need to be mapped in user mode.
> + */

WARNING: line over 100 characters
#122: FILE: include/linux/percpu-defs.h:186:
+ * Declaration/definition used for per-CPU variables that must be page aligned and need to be mapped in user mode.

> +#define DECLARE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \
> + DECLARE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \
> + __aligned(PAGE_SIZE)
> +
> +#define DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(type, name) \
> + DEFINE_PER_CPU_SECTION(type, name, USER_MAPPED_SECTION"..page_aligned") \
> + __aligned(PAGE_SIZE)
>
> /*
> * Declaration/definition used for per-CPU variables that must be read mostly.
> --

With that:

Reviewed-by: Borislav Petkov <bp@suse.de>

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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