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    SubjectRe: [PATCH 08/62] x86/boot/compressed/64: Add IDT Infrastructure
    Hi Andy,

    thanks a lot for your valuable reviews!

    On Tue, Feb 11, 2020 at 02:18:52PM -0800, Andy Lutomirski wrote:
    > On Tue, Feb 11, 2020 at 5:53 AM Joerg Roedel <joro@8bytes.org> wrote:
    > > + entry.offset_low = (u16)(address & 0xffff);
    > > + entry.segment = __KERNEL_CS;
    > > + entry.bits.type = GATE_TRAP;
    >
    > ^^^
    >
    > I realize we're not running a real kernel here, but GATE_TRAP is
    > madness. Please use GATE_INTERRUPT.

    Changed that.

    > > + /* Build pt_regs */
    > > + .if \error_code == 0
    > > + pushq $0
    > > + .endif
    >
    > cld

    Added.

    > > + popq %rdi
    >
    > if error_code?

    The code above pushes a $0 for exceptions without an error code, so it
    needs to be removed unconditionally.

    > > +
    > > + /* Remove error code and return */
    > > + addq $8, %rsp
    > > +
    > > + /*
    > > + * Make sure we return to __KERNEL_CS - the CS selector on
    > > + * the IRET frame might still be from an old BIOS GDT
    > > + */
    > > + movq $__KERNEL_CS, 8(%rsp)
    > > +
    >
    > If this actually happens, you have a major bug. Please sanitize all
    > the segment registers after installing the GDT rather than hacking
    > around it here.

    Okay, will change that. I thought I could safe some instructions in the
    head_64.S code, but you are right that its better to setup a defined
    environment first.


    Thanks,

    Joerg

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