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 can be used no matter which copy of the page tables we are using. Thanks to Hugh Dickins for cleanups to this code. Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: Moritz Lipp <moritz.lipp@xxxxxxxxxxxxxx> Cc: Daniel Gruss <daniel.gruss@xxxxxxxxxxxxxx> Cc: Michael Schwarz <michael.schwarz@xxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: x86@xxxxxxxxxx --- b/arch/x86/include/asm/desc.h | 2 +- b/arch/x86/include/asm/hw_irq.h | 2 +- b/arch/x86/include/asm/processor.h | 2 +- b/arch/x86/kernel/cpu/common.c | 4 ++-- b/arch/x86/kernel/irqinit.c | 2 +- b/arch/x86/kernel/process.c | 2 +- b/include/asm-generic/vmlinux.lds.h | 7 +++++++ b/include/linux/percpu-defs.h | 32 +++++++++++++++++++++++++++++++- 8 files changed, 45 insertions(+), 8 deletions(-) diff -puN arch/x86/include/asm/desc.h~kaiser-prep-user-mapped-percpu arch/x86/include/asm/desc.h --- a/arch/x86/include/asm/desc.h~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.046146272 -0700 +++ b/arch/x86/include/asm/desc.h 2017-10-31 15:03:51.066147217 -0700 @@ -45,7 +45,7 @@ struct gdt_page { struct desc_struct gdt[GDT_ENTRIES]; } __attribute__((aligned(PAGE_SIZE))); -DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page); +DECLARE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(struct gdt_page, gdt_page); /* Provide the original GDT */ static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu) diff -puN arch/x86/include/asm/hw_irq.h~kaiser-prep-user-mapped-percpu arch/x86/include/asm/hw_irq.h --- a/arch/x86/include/asm/hw_irq.h~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.048146366 -0700 +++ b/arch/x86/include/asm/hw_irq.h 2017-10-31 15:03:51.066147217 -0700 @@ -160,7 +160,7 @@ extern char irq_entries_start[]; #define VECTOR_RETRIGGERED ((void *)~0UL) typedef struct irq_desc* vector_irq_t[NR_VECTORS]; -DECLARE_PER_CPU(vector_irq_t, vector_irq); +DECLARE_PER_CPU_USER_MAPPED(vector_irq_t, vector_irq); #endif /* !ASSEMBLY_ */ diff -puN arch/x86/include/asm/processor.h~kaiser-prep-user-mapped-percpu arch/x86/include/asm/processor.h --- a/arch/x86/include/asm/processor.h~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.051146508 -0700 +++ b/arch/x86/include/asm/processor.h 2017-10-31 15:03:51.067147264 -0700 @@ -348,7 +348,7 @@ struct tss_struct { } ____cacheline_aligned; -DECLARE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss); +DECLARE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct tss_struct, cpu_tss); /* * sizeof(unsigned long) coming from an extra "long" at the end diff -puN arch/x86/kernel/cpu/common.c~kaiser-prep-user-mapped-percpu arch/x86/kernel/cpu/common.c --- a/arch/x86/kernel/cpu/common.c~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.053146603 -0700 +++ b/arch/x86/kernel/cpu/common.c 2017-10-31 15:03:51.067147264 -0700 @@ -98,7 +98,7 @@ static const struct cpu_dev default_cpu static const struct cpu_dev *this_cpu = &default_cpu; -DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = { +DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(struct gdt_page, gdt_page) = { .gdt = { #ifdef CONFIG_X86_64 /* * We need valid kernel segments for data and code in long mode too @@ -1345,7 +1345,7 @@ static const unsigned int exception_stac [DEBUG_STACK - 1] = DEBUG_STKSZ }; -static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks +DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(char, exception_stacks [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]); /* May not be marked __init: used by software suspend */ diff -puN arch/x86/kernel/irqinit.c~kaiser-prep-user-mapped-percpu arch/x86/kernel/irqinit.c --- a/arch/x86/kernel/irqinit.c~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.055146697 -0700 +++ b/arch/x86/kernel/irqinit.c 2017-10-31 15:03:51.068147312 -0700 @@ -51,7 +51,7 @@ static struct irqaction irq2 = { .flags = IRQF_NO_THREAD, }; -DEFINE_PER_CPU(vector_irq_t, vector_irq) = { +DEFINE_PER_CPU_USER_MAPPED(vector_irq_t, vector_irq) = { [0 ... NR_VECTORS - 1] = VECTOR_UNUSED, }; diff -puN arch/x86/kernel/process.c~kaiser-prep-user-mapped-percpu arch/x86/kernel/process.c --- a/arch/x86/kernel/process.c~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.057146792 -0700 +++ b/arch/x86/kernel/process.c 2017-10-31 15:03:51.068147312 -0700 @@ -46,7 +46,7 @@ * section. Since TSS's are completely CPU-local, we want them * on exact cacheline boundaries, to eliminate cacheline ping-pong. */ -__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = { +__visible DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct tss_struct, cpu_tss) = { .x86_tss = { .sp0 = TOP_OF_INIT_STACK, #ifdef CONFIG_X86_32 diff -puN include/asm-generic/vmlinux.lds.h~kaiser-prep-user-mapped-percpu include/asm-generic/vmlinux.lds.h --- a/include/asm-generic/vmlinux.lds.h~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.059146886 -0700 +++ b/include/asm-generic/vmlinux.lds.h 2017-10-31 15:03:51.068147312 -0700 @@ -807,7 +807,14 @@ */ #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 -puN include/linux/percpu-defs.h~kaiser-prep-user-mapped-percpu include/linux/percpu-defs.h --- a/include/linux/percpu-defs.h~kaiser-prep-user-mapped-percpu 2017-10-31 15:03:51.062147028 -0700 +++ b/include/linux/percpu-defs.h 2017-10-31 15:03:51.069147359 -0700 @@ -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 @@ -162,11 +182,21 @@ #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. + */ +#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. */ -#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ +#define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ DECLARE_PER_CPU_SECTION(type, name, "..read_mostly") #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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