Re: [PATCH v2] x86: Handle 64bit framebuffer memory address properly

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On Mon, Jan 28, 2019 at 6:53 PM Simon Horman <horms@xxxxxxxxxxxx> wrote:
>
> On Tue, Jan 22, 2019 at 10:25:42AM +0800, Kairui Song wrote:
> > On Wed, Dec 5, 2018 at 5:22 PM Kairui Song <kasong@xxxxxxxxxx> wrote:
> > >
> > > In a EFI system, the frame buffer address is 64bit, so currently
> > > if the address is beyound 4G, kexec will set wrong address due to
> > > truncate.
> > >
> > > Linux kernel commit ae2ee627dc87 ('efifb: Add support for 64-bit
> > > frame buffer addresses') added support for 64bit frame buffer
> > > address, an 'ext_lfb_base' field is added as the upper 32-bits of
> > > the frame buffer, and introduced a new capability flag
> > > 'VIDEO_TYPE_CAPABILITY_64BIT_BASE' to indicate if the extend field is
> > > used.
> > >
> > > This patch adopts this change, set proper extent address and capability
> > > flag when the address is beyound 4G.
> > >
> > > Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
> > > ---
> > > Update from V1:
> > > - Use 0xffffffffUL instead of 0xffffffff for comparing and bit operation
> > >   with smem_start to make it cleaner and safer, as smem_start is an
> > >   unsigned long.
> > >
> > >  include/x86/x86-linux.h           | 7 +++++--
> > >  kexec/arch/i386/x86-linux-setup.c | 7 ++++++-
> > >  2 files changed, 11 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
> > > index 7834751..352ea02 100644
> > > --- a/include/x86/x86-linux.h
> > > +++ b/include/x86/x86-linux.h
> > > @@ -107,7 +107,10 @@ struct x86_linux_param_header {
> > >         uint16_t vesapm_seg;                    /* 0x2e */
> > >         uint16_t vesapm_off;                    /* 0x30 */
> > >         uint16_t pages;                         /* 0x32 */
> > > -       uint8_t  reserved4[12];                 /* 0x34 -- 0x3f reserved for future expansion */
> > > +       uint16_t vesa_attributes;               /* 0x34 */
> > > +       uint32_t capabilities;                  /* 0x36 */
> > > +       uint32_t ext_lfb_base;                  /* 0x3a */
> > > +       uint8_t  reserved4[2];                  /* 0x3e -- 0x3f reserved for future expansion */
> > >
> > >         struct apm_bios_info apm_bios_info;     /* 0x40 */
> > >         struct drive_info_struct drive_info;    /* 0x80 */
> > > @@ -199,7 +202,7 @@ struct x86_linux_param_header {
> > >         struct  edd_info eddbuf[EDDMAXNR];      /* 0xd00 */
> > >                                                 /* 0xeec */
> > >  #define COMMAND_LINE_SIZE 2048
> > > -};
> > > +} __attribute__((packed));
> > >
> > >  struct x86_linux_faked_param_header {
> > >         struct x86_linux_param_header hdr;      /* 0x00 */
> > > diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
> > > index 6cda12c..1bd408b 100644
> > > --- a/kexec/arch/i386/x86-linux-setup.c
> > > +++ b/kexec/arch/i386/x86-linux-setup.c
> > > @@ -158,10 +158,15 @@ static int setup_linux_vesafb(struct x86_linux_param_header *real_mode)
> > >         real_mode->lfb_width      = var.xres;
> > >         real_mode->lfb_height     = var.yres;
> > >         real_mode->lfb_depth      = var.bits_per_pixel;
> > > -       real_mode->lfb_base       = fix.smem_start;
> > > +       real_mode->lfb_base       = fix.smem_start & 0xffffffffUL;
> > >         real_mode->lfb_linelength = fix.line_length;
> > >         real_mode->vesapm_seg     = 0;
> > >
> > > +       if (fix.smem_start > 0xffffffffUL) {
> > > +               real_mode->ext_lfb_base = fix.smem_start >> 32;
> > > +               real_mode->capabilities |= VIDEO_CAPABILITY_64BIT_BASE;
> > > +       }
> > > +
> > >         /* FIXME: better get size from the file returned by proc_iomem() */
> > >         real_mode->lfb_size       = (fix.smem_len + 65535) / 65536;
> > >         real_mode->pages          = (fix.smem_len + 4095) / 4096;
> > > --
> > > 2.19.1
> > >
> >
> > Hi Simon,
> >
> > Could you please have a look of this patch? Thanks
>
> Sorry, for the delay.
> This got stuck in my TODO list for way to long.
>
> This patch looks good to me and I have applied it for
> inclusion in the next release of kexec-tools.

No worry, thanks for the merge.

--
Best Regards,
Kairui Song

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