Messages in this thread Patch in this message | | | From | Ingo Molnar <> | Subject | [PATCH 28/43] x86/mm/kaiser: Map cpu entry area | Date | Fri, 24 Nov 2017 18:23:56 +0100 |
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From: Dave Hansen <dave.hansen@linux.intel.com>
There is now a special 'struct cpu_entry' area that contains all of the data needed to enter the kernel. It's mapped in the fixmap area and contains:
* The GDT (hardware segment descriptor) * The TSS (thread information structure that points the hardware to the various stacks, and contains the entry stack). * The entry trampoline code itself * The exception stacks (aka IRQ stacks)
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/20171123003453.D4CB33A9@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/include/asm/kaiser.h | 6 ++++++ arch/x86/kernel/cpu/common.c | 4 ++++ arch/x86/mm/kaiser.c | 31 +++++++++++++++++++++++++++++++ include/linux/kaiser.h | 3 +++ 4 files changed, 44 insertions(+)
diff --git a/arch/x86/include/asm/kaiser.h b/arch/x86/include/asm/kaiser.h index 3c2cc71b4058..040cb096d29d 100644 --- a/arch/x86/include/asm/kaiser.h +++ b/arch/x86/include/asm/kaiser.h @@ -33,6 +33,12 @@ extern int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long flags); +/** + * kaiser_add_mapping_cpu_entry - map the cpu entry area + * @cpu: the CPU for which the entry area is being mapped + */ +extern void kaiser_add_mapping_cpu_entry(int cpu); + /** * kaiser_remove_mapping - remove a kernel mapping from the userpage tables * @addr: the start address of the range diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 3b6920c9fef7..d6bcf397b00d 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -4,6 +4,7 @@ #include <linux/kernel.h> #include <linux/export.h> #include <linux/percpu.h> +#include <linux/kaiser.h> #include <linux/string.h> #include <linux/ctype.h> #include <linux/delay.h> @@ -584,6 +585,9 @@ static inline void setup_cpu_entry_area(int cpu) __set_fixmap(get_cpu_entry_area_index(cpu, entry_trampoline), __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX); #endif + /* CPU 0's mapping is done in kaiser_init() */ + if (cpu) + kaiser_add_mapping_cpu_entry(cpu); } /* Load the original GDT from the per-cpu structure */ diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c index 7f7561e9971d..4665dd724efb 100644 --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -353,6 +353,26 @@ static void __init kaiser_init_all_pgds(void) WARN_ON(__ret); \ } while (0) +void kaiser_add_mapping_cpu_entry(int cpu) +{ + kaiser_add_user_map_early(get_cpu_gdt_ro(cpu), PAGE_SIZE, + __PAGE_KERNEL_RO); + + /* includes the entry stack */ + kaiser_add_user_map_early(&get_cpu_entry_area(cpu)->tss, + sizeof(get_cpu_entry_area(cpu)->tss), + __PAGE_KERNEL | _PAGE_GLOBAL); + + /* Entry code, so needs to be EXEC */ + kaiser_add_user_map_early(&get_cpu_entry_area(cpu)->entry_trampoline, + sizeof(get_cpu_entry_area(cpu)->entry_trampoline), + __PAGE_KERNEL_EXEC | _PAGE_GLOBAL); + + kaiser_add_user_map_early(&get_cpu_entry_area(cpu)->exception_stacks, + sizeof(get_cpu_entry_area(cpu)->exception_stacks), + __PAGE_KERNEL | _PAGE_GLOBAL); +} + extern char __per_cpu_user_mapped_start[], __per_cpu_user_mapped_end[]; /* * If anything in here fails, we will likely die on one of the @@ -390,6 +410,17 @@ void __init kaiser_init(void) kaiser_add_user_map_early((void *)idt_descr.address, sizeof(gate_desc) * NR_VECTORS, __PAGE_KERNEL_RO | _PAGE_GLOBAL); + + /* + * We delay CPU 0's mappings because these structures are + * created before the page allocator is up. Deferring it + * until here lets us use the plain page allocator + * unconditionally in the page table code above. + * + * This is OK because kaiser_init() is called long before + * we ever run userspace and need the KAISER mappings. + */ + kaiser_add_mapping_cpu_entry(0); } int kaiser_add_mapping(unsigned long addr, unsigned long size, diff --git a/include/linux/kaiser.h b/include/linux/kaiser.h index 0fd800efa95c..77db4230a0dd 100644 --- a/include/linux/kaiser.h +++ b/include/linux/kaiser.h @@ -25,5 +25,8 @@ static inline int kaiser_add_mapping(unsigned long addr, unsigned long size, return 0; } +static inline void kaiser_add_mapping_cpu_entry(int cpu) +{ +} #endif /* !CONFIG_KAISER */ #endif /* _INCLUDE_KAISER_H */ -- 2.14.1
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