Re: [PATCH 1/2] efi/gop: Fix return value of setup_gop32/64

[Arvind Sankar <nivedita@alum.mit.edu>]

On Wed, Dec 04, 2019 at 03:03:04PM +0000, Ard Biesheuvel wrote:
> On Tue, 3 Dec 2019 at 21:47, Arvind Sankar <nivedita@alum.mit.edu> wrote:
> >
> > There are two ways the status return of setup_gop32/64 could be
> > incorrect.
> >
> > 1. If we don't find a usable GOP because none of them have a framebuffer
> > (i.e. they were all PIXEL_BLT_ONLY), but all the efi calls succeeded, we
> > will return EFI_SUCCESS even though we didn't find a usable GOP. Return
> > EFI_NOT_FOUND instead, allowing the caller to probe for UGA instead.
> >
> > 2. If we do find a usable GOP, but one of the subsequent ones fails in
> > an EFI call while checking if any support console output, we may return
> > an EFI error code even though we found a usable GOP. Fix this by always
> > returning EFI_SUCCESS if we got a usable GOP.
> >
> 
> Please split this into 2 patches

Not quite following -- what should be the two pieces? Are you saying to
split the success return and the failure return into two patches -- that
seems excessively fine-grained.

> 
> > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
> > ---
> >  drivers/firmware/efi/libstub/gop.c | 16 ++++++++--------
> >  1 file changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/libstub/gop.c b/drivers/firmware/efi/libstub/gop.c
> > index 0101ca4c13b1..235a98797105 100644
> > --- a/drivers/firmware/efi/libstub/gop.c
> > +++ b/drivers/firmware/efi/libstub/gop.c
> > @@ -119,7 +119,6 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >         u64 fb_base;
> >         struct efi_pixel_bitmask pixel_info;
> >         int pixel_format;
> > -       efi_status_t status = EFI_NOT_FOUND;
> 
> Is it really necessary to move this declaration?

No, I just moved it inside the loop block since it's not used outside
any more.

> 
> >         u32 *handles = (u32 *)(unsigned long)gop_handle;
> >         int i;
> >
> > @@ -134,6 +133,7 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >                 void *dummy = NULL;
> >                 efi_handle_t h = (efi_handle_t)(unsigned long)handles[i];
> >                 u64 current_fb_base;
> > +               efi_status_t status;
> >
> >                 status = efi_call_early(handle_protocol, h,
> >                                         proto, (void **)&gop32);
> > @@ -175,7 +175,7 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >
> >         /* Did we find any GOPs? */
> >         if (!first_gop)
> > -               goto out;
> > +               return EFI_NOT_FOUND;
> >
> >         /* EFI framebuffer */
> >         si->orig_video_isVGA = VIDEO_TYPE_EFI;
> > @@ -197,8 +197,8 @@ setup_gop32(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >         si->lfb_size = si->lfb_linelength * si->lfb_height;
> >
> >         si->capabilities |= VIDEO_CAPABILITY_SKIP_QUIRKS;
> > -out:
> > -       return status;
> > +
> > +       return EFI_SUCCESS;
> >  }
> >
> >  static efi_status_t
> > @@ -237,7 +237,6 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >         u64 fb_base;
> >         struct efi_pixel_bitmask pixel_info;
> >         int pixel_format;
> > -       efi_status_t status = EFI_NOT_FOUND;
> >         u64 *handles = (u64 *)(unsigned long)gop_handle;
> >         int i;
> >
> > @@ -252,6 +251,7 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >                 void *dummy = NULL;
> >                 efi_handle_t h = (efi_handle_t)(unsigned long)handles[i];
> >                 u64 current_fb_base;
> > +               efi_status_t status;
> >
> >                 status = efi_call_early(handle_protocol, h,
> >                                         proto, (void **)&gop64);
> > @@ -293,7 +293,7 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >
> >         /* Did we find any GOPs? */
> >         if (!first_gop)
> > -               goto out;
> > +               return EFI_NOT_FOUND;
> >
> >         /* EFI framebuffer */
> >         si->orig_video_isVGA = VIDEO_TYPE_EFI;
> > @@ -315,8 +315,8 @@ setup_gop64(efi_system_table_t *sys_table_arg, struct screen_info *si,
> >         si->lfb_size = si->lfb_linelength * si->lfb_height;
> >
> >         si->capabilities |= VIDEO_CAPABILITY_SKIP_QUIRKS;
> > -out:
> > -       return status;
> > +
> > +       return EFI_SUCCESS;
> >  }
> >
> >  /*
> > --
> > 2.23.0
> >