Messages in this thread Patch in this message | | | Subject | [PATCH 08/23] x86, kaiser: map cpu entry area | From | Dave Hansen <> | Date | Wed, 22 Nov 2017 16:34:53 -0800 |
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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> Cc: Moritz Lipp <moritz.lipp@iaik.tugraz.at> Cc: Daniel Gruss <daniel.gruss@iaik.tugraz.at> Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at> Cc: Richard Fellner <richard.fellner@student.tugraz.at> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Kees Cook <keescook@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: x86@kernel.org ---
b/arch/x86/include/asm/kaiser.h | 6 ++++++ b/arch/x86/kernel/cpu/common.c | 4 ++++ b/arch/x86/mm/kaiser.c | 31 +++++++++++++++++++++++++++++++ b/include/linux/kaiser.h | 3 +++ 4 files changed, 44 insertions(+)
diff -puN arch/x86/include/asm/kaiser.h~kaiser-user-map-cpu-entry-structure arch/x86/include/asm/kaiser.h --- a/arch/x86/include/asm/kaiser.h~kaiser-user-map-cpu-entry-structure 2017-11-22 15:45:48.447619740 -0800 +++ b/arch/x86/include/asm/kaiser.h 2017-11-22 15:45:48.456619740 -0800 @@ -34,6 +34,12 @@ extern int kaiser_add_mapping(unsigned l 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 * @size: the size of the range diff -puN arch/x86/kernel/cpu/common.c~kaiser-user-map-cpu-entry-structure arch/x86/kernel/cpu/common.c --- a/arch/x86/kernel/cpu/common.c~kaiser-user-map-cpu-entry-structure 2017-11-22 15:45:48.449619740 -0800 +++ b/arch/x86/kernel/cpu/common.c 2017-11-22 15:45:48.457619740 -0800 @@ -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> @@ -587,6 +588,9 @@ static inline void setup_cpu_entry_area( __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 -puN arch/x86/mm/kaiser.c~kaiser-user-map-cpu-entry-structure arch/x86/mm/kaiser.c --- a/arch/x86/mm/kaiser.c~kaiser-user-map-cpu-entry-structure 2017-11-22 15:45:48.451619740 -0800 +++ b/arch/x86/mm/kaiser.c 2017-11-22 15:45:48.457619740 -0800 @@ -353,6 +353,26 @@ static void __init kaiser_init_all_pgds( 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 -puN include/linux/kaiser.h~kaiser-user-map-cpu-entry-structure include/linux/kaiser.h --- a/include/linux/kaiser.h~kaiser-user-map-cpu-entry-structure 2017-11-22 15:45:48.453619740 -0800 +++ b/include/linux/kaiser.h 2017-11-22 15:45:48.458619740 -0800 @@ -25,5 +25,8 @@ static inline int kaiser_add_mapping(uns return 0; } +static inline void kaiser_add_mapping_cpu_entry(int cpu) +{ +} #endif /* !CONFIG_KAISER */ #endif /* _INCLUDE_KAISER_H */ _
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