Hi Dave, thanks for the review.
It should be safe, "smem_start" is defined as an unsigned long and with 32bit
it will always smaller than 0xffffffff, but to make it cleaner and
safer I will update the
patch to use 0xffffffffUL instead.
On Tue, Dec 4, 2018 at 7:50 PM Dave Young <dyoung@xxxxxxxxxx> wrote:
>
> Hi Kairui,
>
> On 11/23/18 at 05:26pm, Kairui Song 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>
> > ---
> > 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..dc785a2 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 & 0xffffffff;
> > real_mode->lfb_linelength = fix.line_length;
> > real_mode->vesapm_seg = 0;
> >
> > + if (fix.smem_start > 0xffffffff) {
>
> This might be a problem for 32 bit case? Other than this I do not see
> other issues of this patch.
>
> > + 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
> >
> >
> > _______________________________________________
> > kexec mailing list
> > kexec@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/kexec
>
> Thanks
> Dave
--
Best Regards,
Kairui Song
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