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    Subject[tip:x86/apic] x86/idt: Switch early trap init to IDT tables
    Commit-ID:  433f8924fa8e55a50ce57f3b8a33ed095c405644
    Gitweb: http://git.kernel.org/tip/433f8924fa8e55a50ce57f3b8a33ed095c405644
    Author: Thomas Gleixner <tglx@linutronix.de>
    AuthorDate: Mon, 28 Aug 2017 08:47:50 +0200
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Tue, 29 Aug 2017 12:07:27 +0200

    x86/idt: Switch early trap init to IDT tables

    Add the initialization table for the early trap setup and replace the early
    trap init code.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Link: http://lkml.kernel.org/r/20170828064958.929139008@linutronix.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/kernel/idt.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++
    arch/x86/kernel/setup.c | 4 ++--
    arch/x86/kernel/traps.c | 27 -------------------------
    3 files changed, 55 insertions(+), 29 deletions(-)

    diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
    index ae6fc12..64e2211 100644
    --- a/arch/x86/kernel/idt.c
    +++ b/arch/x86/kernel/idt.c
    @@ -48,6 +48,28 @@ struct idt_data {
    #define TSKG(_vector, _gdt) \
    G(_vector, NULL, DEFAULT_STACK, GATE_TASK, DPL0, _gdt << 3)

    +/*
    + * Early traps running on the DEFAULT_STACK because the other interrupt
    + * stacks work only after cpu_init().
    + */
    +static const __initdata struct idt_data early_idts[] = {
    + INTG(X86_TRAP_DB, debug),
    + SYSG(X86_TRAP_BP, int3),
    +#ifdef CONFIG_X86_32
    + INTG(X86_TRAP_PF, page_fault),
    +#endif
    +};
    +
    +#ifdef CONFIG_X86_64
    +/*
    + * Early traps running on the DEFAULT_STACK because the other interrupt
    + * stacks work only after cpu_init().
    + */
    +static const __initdata struct idt_data early_pf_idts[] = {
    + INTG(X86_TRAP_PF, page_fault),
    +};
    +#endif
    +
    /* Must be page-aligned because the real IDT is used in a fixmap. */
    gate_desc idt_table[IDT_ENTRIES] __page_aligned_bss;

    @@ -93,6 +115,37 @@ idt_setup_from_table(gate_desc *idt, const struct idt_data *t, int size)
    }

    /**
    + * idt_setup_early_traps - Initialize the idt table with early traps
    + *
    + * On X8664 these traps do not use interrupt stacks as they can't work
    + * before cpu_init() is invoked and sets up TSS. The IST variants are
    + * installed after that.
    + */
    +void __init idt_setup_early_traps(void)
    +{
    + idt_setup_from_table(idt_table, early_idts, ARRAY_SIZE(early_idts));
    + load_idt(&idt_descr);
    +}
    +
    +#ifdef CONFIG_X86_64
    +/**
    + * idt_setup_early_pf - Initialize the idt table with early pagefault handler
    + *
    + * On X8664 this does not use interrupt stacks as they can't work before
    + * cpu_init() is invoked and sets up TSS. The IST variant is installed
    + * after that.
    + *
    + * FIXME: Why is 32bit and 64bit installing the PF handler at different
    + * places in the early setup code?
    + */
    +void __init idt_setup_early_pf(void)
    +{
    + idt_setup_from_table(idt_table, early_pf_idts,
    + ARRAY_SIZE(early_pf_idts));
    +}
    +#endif
    +
    +/**
    * idt_setup_early_handler - Initializes the idt table with early handlers
    */
    void __init idt_setup_early_handler(void)
    diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
    index ecab322..30dc84e 100644
    --- a/arch/x86/kernel/setup.c
    +++ b/arch/x86/kernel/setup.c
    @@ -891,7 +891,7 @@ void __init setup_arch(char **cmdline_p)
    */
    olpc_ofw_detect();

    - early_trap_init();
    + idt_setup_early_traps();
    early_cpu_init();
    early_ioremap_init();

    @@ -1162,7 +1162,7 @@ void __init setup_arch(char **cmdline_p)

    init_mem_mapping();

    - early_trap_pf_init();
    + idt_setup_early_pf();

    /*
    * Update mmu_cr4_features (and, indirectly, trampoline_cr4_features)
    diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
    index 41f4cd3..835c7e8 100644
    --- a/arch/x86/kernel/traps.c
    +++ b/arch/x86/kernel/traps.c
    @@ -923,33 +923,6 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
    }
    #endif

    -/* Set of traps needed for early debugging. */
    -void __init early_trap_init(void)
    -{
    - /*
    - * Don't use IST to set DEBUG_STACK as it doesn't work until TSS
    - * is ready in cpu_init() <-- trap_init(). Before trap_init(),
    - * CPU runs at ring 0 so it is impossible to hit an invalid
    - * stack. Using the original stack works well enough at this
    - * early stage. DEBUG_STACK will be equipped after cpu_init() in
    - * trap_init().
    - */
    - set_intr_gate(X86_TRAP_DB, debug);
    - /* int3 can be called from all */
    - set_system_intr_gate(X86_TRAP_BP, &int3);
    -#ifdef CONFIG_X86_32
    - set_intr_gate(X86_TRAP_PF, page_fault);
    -#endif
    - load_idt(&idt_descr);
    -}
    -
    -void __init early_trap_pf_init(void)
    -{
    -#ifdef CONFIG_X86_64
    - set_intr_gate(X86_TRAP_PF, page_fault);
    -#endif
    -}
    -
    void __init trap_init(void)
    {
    int i;
    \
     
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