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    Subject[tip: x86/entry] x86/idt: Add comments about early #PF handling
    The following commit has been merged into the x86/entry branch of tip:

    Commit-ID: 66d2e706c0cecd09b1f3de4844574d30e5469c28
    Gitweb: https://git.kernel.org/tip/66d2e706c0cecd09b1f3de4844574d30e5469c28
    Author: Thomas Gleixner <tglx@linutronix.de>
    AuthorDate: Thu, 28 May 2020 16:53:17 +02:00
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitterDate: Sat, 30 May 2020 11:50:11 +02:00

    x86/idt: Add comments about early #PF handling

    The difference between 32 and 64 bit vs. early #PF handling is not
    documented. Replace the FIXME at idt_setup_early_pf() with proper comments.

    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Link: https://lkml.kernel.org/r/20200528145522.807135882@linutronix.de

    ---
    arch/x86/kernel/idt.c | 10 ++++++++--
    1 file changed, 8 insertions(+), 2 deletions(-)

    diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
    index 4b99f7b..5ef82fc 100644
    --- a/arch/x86/kernel/idt.c
    +++ b/arch/x86/kernel/idt.c
    @@ -61,7 +61,11 @@ static bool idt_setup_done __initdata;
    static const __initconst struct idt_data early_idts[] = {
    INTG(X86_TRAP_DB, asm_exc_debug),
    SYSG(X86_TRAP_BP, asm_exc_int3),
    +
    #ifdef CONFIG_X86_32
    + /*
    + * Not possible on 64-bit. See idt_setup_early_pf() for details.
    + */
    INTG(X86_TRAP_PF, asm_exc_page_fault),
    #endif
    };
    @@ -256,8 +260,10 @@ void __init idt_setup_traps(void)
    * 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?
    + * Note, that X86_64 cannot install the real #PF handler in
    + * idt_setup_early_traps() because the memory intialization needs the #PF
    + * handler from the early_idt_handler_array to initialize the early page
    + * tables.
    */
    void __init idt_setup_early_pf(void)
    {
    \
     
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