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10043e02db
The Intel PEBS/BTS debug store is a design trainwreck as it expects virtual addresses which must be visible in any execution context. So it is required to make these mappings visible to user space when kernel page table isolation is active. Provide enough room for the buffer mappings in the cpu_entry_area so the buffers are available in the user space visible page tables. At the point where the kernel side entry area is populated there is no buffer available yet, but the kernel PMD must be populated. To achieve this set the entries for these buffers to non present. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
82 lines
2.3 KiB
C
82 lines
2.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef _ASM_X86_CPU_ENTRY_AREA_H
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#define _ASM_X86_CPU_ENTRY_AREA_H
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#include <linux/percpu-defs.h>
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#include <asm/processor.h>
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#include <asm/intel_ds.h>
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/*
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* cpu_entry_area is a percpu region that contains things needed by the CPU
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* and early entry/exit code. Real types aren't used for all fields here
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* to avoid circular header dependencies.
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*
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* Every field is a virtual alias of some other allocated backing store.
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* There is no direct allocation of a struct cpu_entry_area.
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*/
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struct cpu_entry_area {
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char gdt[PAGE_SIZE];
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/*
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* The GDT is just below entry_stack and thus serves (on x86_64) as
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* a a read-only guard page.
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*/
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struct entry_stack_page entry_stack_page;
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/*
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* On x86_64, the TSS is mapped RO. On x86_32, it's mapped RW because
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* we need task switches to work, and task switches write to the TSS.
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*/
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struct tss_struct tss;
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char entry_trampoline[PAGE_SIZE];
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#ifdef CONFIG_X86_64
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/*
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* Exception stacks used for IST entries.
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*
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* In the future, this should have a separate slot for each stack
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* with guard pages between them.
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*/
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char exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ];
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#endif
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#ifdef CONFIG_CPU_SUP_INTEL
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/*
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* Per CPU debug store for Intel performance monitoring. Wastes a
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* full page at the moment.
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*/
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struct debug_store cpu_debug_store;
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/*
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* The actual PEBS/BTS buffers must be mapped to user space
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* Reserve enough fixmap PTEs.
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*/
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struct debug_store_buffers cpu_debug_buffers;
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#endif
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};
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#define CPU_ENTRY_AREA_SIZE (sizeof(struct cpu_entry_area))
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#define CPU_ENTRY_AREA_TOT_SIZE (CPU_ENTRY_AREA_SIZE * NR_CPUS)
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DECLARE_PER_CPU(struct cpu_entry_area *, cpu_entry_area);
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extern void setup_cpu_entry_areas(void);
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extern void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags);
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#define CPU_ENTRY_AREA_RO_IDT CPU_ENTRY_AREA_BASE
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#define CPU_ENTRY_AREA_PER_CPU (CPU_ENTRY_AREA_RO_IDT + PAGE_SIZE)
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#define CPU_ENTRY_AREA_RO_IDT_VADDR ((void *)CPU_ENTRY_AREA_RO_IDT)
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#define CPU_ENTRY_AREA_MAP_SIZE \
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(CPU_ENTRY_AREA_PER_CPU + CPU_ENTRY_AREA_TOT_SIZE - CPU_ENTRY_AREA_BASE)
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extern struct cpu_entry_area *get_cpu_entry_area(int cpu);
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static inline struct entry_stack *cpu_entry_stack(int cpu)
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{
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return &get_cpu_entry_area(cpu)->entry_stack_page.stack;
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}
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#endif
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