Re: [Minios-devel] [UNIKRAFT PATCH v2 01/18] plat/kvm: Place early boot code to the start of the image (x86)

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey,

thanks for the review. I screwed up the patch subject as well, it is 
just a single patch (not part of 18). Sorry for this.
Thanks,

Simon

On 13.06.2018 12:49, Yuri Volchkov wrote:
> Sorry, I screwed up my previous email :)
> This is how it supposed to look like:
>
> Reviewed-by: Yuri Volchkov  <yuri.volchkov@xxxxxxxxx>
>
> Simon Kuenzer <simon.kuenzer@xxxxxxxxx> writes:
>
> > Places early boot code (e.g., 64bit mode switch) and
> > data (e.g., GDT) to the start of the image.
> > This avoids general protection faults that were caused
> > whenever the linker placed such items to addresses
> > that were not accessible while the mode switch to 64bit
> > and address space setup was not finished.
> >
> > Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> > ---
> >   plat/kvm/x86/entry64.S | 21 ++++++++++++---------
> >   plat/kvm/x86/link64.ld |  3 ++-
> >   2 files changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/plat/kvm/x86/entry64.S b/plat/kvm/x86/entry64.S
> > index bda7d40..1a10359 100644
> > --- a/plat/kvm/x86/entry64.S
> > +++ b/plat/kvm/x86/entry64.S
> > @@ -30,24 +30,24 @@
> >   #include <x86/cpu_defs.h>
> >   #include <kvm-x86/multiboot_defs.h>
> >   
> > -#define ENTRY(x) .text; .globl x; .type x,%function; x:
> > +#define ENTRY(x) .globl x; .type x,%function; x:
> >   #define END(x)   .size x, . - x
> >   
> >   #define MYMULTIBOOT_FLAGS \
> >       (MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE)
> >   
> > -.section .data.multiboot
> > +.section .data.boot
> >   
> >   .align 4
> >   _multiboot_header:
> >   .long MULTIBOOT_HEADER_MAGIC
> >   .long MYMULTIBOOT_FLAGS
> > -.long -(MULTIBOOT_HEADER_MAGIC+MYMULTIBOOT_FLAGS)
> > -.long _multiboot_header
> > -.long 0x100000
> > -.long _edata
> > -.long _end
> > -.long _libkvmplat_start32
> > +.long -(MULTIBOOT_HEADER_MAGIC+MYMULTIBOOT_FLAGS) /* checksum */
> > +.long _multiboot_header                           /* header addr */
> > +.long 0x100000                                    /* load addr */
> > +.long _edata                                      /* load end addr */
> > +.long _end                                        /* bss end addr */
> > +.long _libkvmplat_start32                         /* entry addr */
> >   
> >   .section .bss
> >   
> > @@ -63,6 +63,7 @@ bootstack:
> >    * we've switched to long mode.
> >    */
> >   .code32
> > +.section .text.boot
> >   
> >   ENTRY(_libkvmplat_start32)
> >         cld
> > @@ -139,7 +140,7 @@ END(_libkvmplat_start32)
> >    * Uuuyea, exceptions.
> >    */
> >   
> > -.data
> > +.section .data.boot
> >   .align 64
> >   gdt64:
> >         .quad 0x0000000000000000
> > @@ -165,6 +166,7 @@ mxcsr_ptr:
> >   #include "pagetable.S"
> >   
> >   .code64
> > +.section .text.boot
> >   
> >   ENTRY(_libkvmplat_start64)
> >         movq $bootstack, %rsp
> > @@ -192,6 +194,7 @@ ENTRY(_libkvmplat_start64)
> >         hlt
> >   END(_libkvmplat_start64)
> >   
> > +.text
> >   ENTRY(_libkvmplat_newstack)
> >         movq %rdi, %rsp
> >         movq %rdx, %rdi
> > diff --git a/plat/kvm/x86/link64.ld b/plat/kvm/x86/link64.ld
> > index d1bfa73..60b5d21 100644
> > --- a/plat/kvm/x86/link64.ld
> > +++ b/plat/kvm/x86/link64.ld
> > @@ -33,7 +33,8 @@ SECTIONS
> >         .text :
> >         {
> >                 /* prevent linker gc from removing multiboot header */
> > -               KEEP (*(.data.multiboot))
> > +               KEEP (*(.data.boot))
> > +               *(.text.boot)
> >   
> >   		*(.text)
> >                 *(.text.*)
> > --
> > 2.7.4
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