Re: [PATCH v5 2/7] x86/sysfb: fix lfb_size calculation

On Fri, Sep 2, 2016 at 10:22 AM, David Herrmann dh.herrmann@gmail.com wrote:

The screen_info.lfb_size field is shifted by 16 bits *only* in case of VBE. This has historical reasons since VBE advertised it similarly. However, in case of EFI framebuffers, the size is no longer shifted. Fix the x86 simple-framebuffer setup code to use the correct size in the non-VBE case.

While at it, avoid variable abbreviations and rename 'len' to 'length', and use the correct types matching the screen_info definition.

Signed-off-by: David Herrmann dh.herrmann@gmail.com

Reviewed-by: Tom Gundersen teg@jklm.no

---

arch/x86/kernel/sysfb_simplefb.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c index 35b8641..85195d4 100644 --- a/arch/x86/kernel/sysfb_simplefb.c +++ b/arch/x86/kernel/sysfb_simplefb.c @@ -66,8 +66,8 @@ __init int create_simplefb(const struct screen_info *si, { struct platform_device *pd; struct resource res;

•   unsigned long len;
  

•   u64 base;
  

•   u64 base, size;
  

•   u32 length;
  
    /*
     * If the 64BIT_BASE capability is set, ext_lfb_base will contain the
  

@@ -82,11 +82,20 @@ __init int create_simplefb(const struct screen_info *si, return -EINVAL; }

•   /* don't use lfb_size as it may contain the whole VMEM instead of only
  

•    * the part that is occupied by the framebuffer */
  

•   len = mode->height * mode->stride;
  

•   len = PAGE_ALIGN(len);
  

•   if (len > (u64)si->lfb_size << 16) {
  

•   /*
  

•    * Don't use lfb_size as IORESOURCE size, since it may contain the
  

•    * entire VMEM, and thus require huge mappings. Use just the part we
  

•    * need, that is, the part where the framebuffer is located. But verify
  

•    * that it does not exceed the advertised VMEM.
  

•    * Note that in case of VBE, the lfb_size is shifted by 16 bits for
  

•    * historical reasons.
  

•    */
  

•   size = si->lfb_size;
  

•   if (si->orig_video_isVGA == VIDEO_TYPE_VLFB)
  

•           size <<= 16;
  

•   length = mode->height * mode->stride;
  

•   length = PAGE_ALIGN(length);
  

•   if (length > size) {
            printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
            return -EINVAL;
    }
  

@@ -96,7 +105,7 @@ __init int create_simplefb(const struct screen_info *si, res.flags = IORESOURCE_MEM | IORESOURCE_BUSY; res.name = simplefb_resname; res.start = base;

•   res.end = res.start + len - 1;
  

•   res.end = res.start + length - 1;
    if (res.end <= res.start)
            return -EINVAL;
  
  

-- 2.9.3

---

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