[U-Boot] [PATCH 1/1] x86: efi_loader: Fix invalid address return from efi_alloc()

[Park, Aiden]

Hi Bin,

> -----Original Message-----
> From: Bin Meng [mailto:bmeng.cn at gmail.com]
> Sent: Wednesday, August 28, 2019 8:37 PM
> To: Park, Aiden <aiden.park at intel.com>; Heinrich Schuchardt
> <xypron.glpk at gmx.de>
> Cc: Simon Glass <sjg at chromium.org>; u-boot at lists.denx.de
> Subject: Re: [PATCH 1/1] x86: efi_loader: Fix invalid address return from
> efi_alloc()
> 
> +Heinrich,
> 
> On Wed, Aug 28, 2019 at 2:35 AM Park, Aiden <aiden.park at intel.com> wrote:
> >
> > This issue can be seen on 32bit operation when one of E820_RAM type
> > entries is greater than 4GB memory space.
> >
> > The efi_alloc() finds a free memory in the conventional memory which
> > is greater than 4GB. But, it does type cast to 32bit address space and
> > eventually returns invalid address.
> >
> > Signed-off-by: Aiden Park <aiden.park at intel.com>
> > ---
> >  arch/x86/lib/e820.c | 22 +++++++++++++++++++++-
> >  1 file changed, 21 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/lib/e820.c b/arch/x86/lib/e820.c index
> > d6ae2c4e9d..3e93931231 100644
> > --- a/arch/x86/lib/e820.c
> > +++ b/arch/x86/lib/e820.c
> > @@ -41,11 +41,15 @@ void efi_add_known_memory(void)  {
> >         struct e820_entry e820[E820MAX];
> >         unsigned int i, num;
> > -       u64 start, pages;
> > +       u64 start, pages, ram_top;
> >         int type;
> >
> >         num = install_e820_map(ARRAY_SIZE(e820), e820);
> >
> > +       ram_top = (u64)gd->ram_top & ~EFI_PAGE_MASK;
> > +       if (!ram_top)
> 
> So for the logic here to work, gd->ram_top is already zero in 32-bit, right? I was
> wondering how U-Boot could boot on such target?
> 
The efi_add_known_memory() in lib/efi_loader/efi_memory.c covers this case.

> > +               ram_top = 0x100000000ULL;
> > +
> >         for (i = 0; i < num; ++i) {
> >                 start = e820[i].addr;
> >                 pages = ALIGN(e820[i].size, EFI_PAGE_SIZE) >>
> > EFI_PAGE_SHIFT; @@ -70,6 +74,22 @@ void efi_add_known_memory(void)
> >                 }
> >
> >                 efi_add_memory_map(start, pages, type, false);
> > +
> > +               if (type == EFI_CONVENTIONAL_MEMORY) {
> > +                       u64 end = start + (pages << EFI_PAGE_SHIFT);
> > +
> > +                       /* reserve the memory region greater than ram_top */
> > +                       if (ram_top < start) {
> > +                               efi_add_memory_map(start, pages,
> > +                                                  EFI_BOOT_SERVICES_DATA,
> > +                                                  true);
> 
> Heinrich, could you please review the changes here?
> 
> > +                       } else if (start < ram_top && ram_top < end) {
> > +                               pages = (end - ram_top) >> EFI_PAGE_SHIFT;
> > +                               efi_add_memory_map(ram_top, pages,
> > +                                                  EFI_BOOT_SERVICES_DATA,
> > +                                                  true);
> > +                       }
> > +               }
> >         }
> >  }
> >  #endif /* CONFIG_IS_ENABLED(EFI_LOADER) */
> > --
> 
> Regards,
> Bin

I have replicated this issue with qemu-x86_defconfig as below.

diff --git a/arch/x86/cpu/qemu/e820.c b/arch/x86/cpu/qemu/e820.c
index e682486547..7e5ae38c07 100644
--- a/arch/x86/cpu/qemu/e820.c
+++ b/arch/x86/cpu/qemu/e820.c
@@ -42,5 +42,9 @@ unsigned int install_e820_map(unsigned int max_entries,
        entries[5].size = CONFIG_PCIE_ECAM_SIZE;
        entries[5].type = E820_RESERVED;

-       return 6;
+       entries[6].addr = 0x100000000ULL;
+       entries[6].size = 0x100000000ULL;
+       entries[6].type = E820_RAM;
+
+       return 7;
 }
diff --git a/configs/qemu-x86_defconfig b/configs/qemu-x86_defconfig
index e71b8a0ee1..2998d18bdd 100644
--- a/configs/qemu-x86_defconfig
+++ b/configs/qemu-x86_defconfig
@@ -41,3 +41,4 @@ CONFIG_FRAMEBUFFER_SET_VESA_MODE=y
 CONFIG_FRAMEBUFFER_VESA_MODE_USER=y
 CONFIG_FRAMEBUFFER_VESA_MODE=0x144
 CONFIG_CONSOLE_SCROLL_LINES=5
+CONFIG_CMD_BOOTEFI_HELLO=y

$ qemu-system-i386 -nographic -bios u-boot.rom -m 8192
=> bootefi hello

Best Regards,
Aiden