u-boot.git/include/efi_variable.h, branch v2021.07-rc5

efi_loader: Avoid emitting efi_var_buf to .GOT

2021-01-20T07:17:17+00:00

Atish reports that on RISC-V, accessing the EFI variables causes
a kernel panic. An objdump of the file verifies that, since the
global pointer for efi_var_buf ends up in .GOT section which is
not mapped in virtual address space for Linux.



0000000000000084 :
  84:   715d                    addi    sp,sp,-80

* objdump -dr
0000000000000086 <.LCFI2>:
  86:   e0a2                    sd  s0,64(sp)
  88:   fc26                    sd  s1,56(sp)
  8a:   e486                    sd  ra,72(sp)
  8c:   f84a                    sd  s2,48(sp)
  8e:   f44e                    sd  s3,40(sp)
  90:   f052                    sd  s4,32(sp)
  92:   ec56                    sd  s5,24(sp)
  94:   00000497            auipc   s1,0x0
            94: R_RISCV_GOT_HI20    efi_var_buf
  98:   0004b483            ld  s1,0(s1) # 94 <.LCFI2+0xe>
            98: R_RISCV_PCREL_LO12_I    .L0
            98: R_RISCV_RELAX   *ABS*

* objdump -t
0000000000000084 g     F .text.efi_runtime  00000000000000b8 efi_var_mem_find

With the patch applied:

* objdump -dr
0000000000000086 <.LCFI2>:
  86:   e0a2                    sd  s0,64(sp)
  88:   fc26                    sd  s1,56(sp)
  8a:   e486                    sd  ra,72(sp)
  8c:   f84a                    sd  s2,48(sp)
  8e:   f44e                    sd  s3,40(sp)
  90:   f052                    sd  s4,32(sp)
  92:   ec56                    sd  s5,24(sp)
  94:   00000497            auipc   s1,0x0
            94: R_RISCV_PCREL_HI20  .LANCHOR0
            94: R_RISCV_RELAX   *ABS*
  98:   00048493            mv  s1,s1
            98: R_RISCV_PCREL_LO12_I    .L0
            98: R_RISCV_RELAX   *ABS*

* objdump -t
0000000000000008 l     O .data.efi_runtime  0000000000000008 efi_var_buf

On arm64 this works, because there's no .GOT entries for this
and everything is converted to relative references.

* objdump -dr (identical pre-post patch, only the new function shows up)
00000000000000b4 :
  b4:   aa0003ee    mov x14, x0
  b8:   9000000a    adrp    x10, 0 
            b8: R_AARCH64_ADR_PREL_PG_HI21  .data.efi_runtime
  bc:   91000140    add x0, x10, #0x0
            bc: R_AARCH64_ADD_ABS_LO12_NC   .data.efi_runtime
  c0:   aa0103ed    mov x13, x1
  c4:   79400021    ldrh    w1, [x1]
  c8:   aa0203eb    mov x11, x2
  cc:   f9400400    ldr x0, [x0, #8]
  d0:   b940100c    ldr w12, [x0, #16]
  d4:   8b0c000c    add x12, x0, x12

So let's switch efi_var_buf to static and create a helper function for
anyone that needs to update it.

Fixes: e01aed47d6a0 ("efi_loader: Enable run-time variable support for tee based variables")
Reported-by: Atish Patra 
Tested-by: Atish Patra 
Signed-off-by: Ilias Apalodimas 
Reviewed-by: Heinrich Schuchardt

efi_loader: make variable store size customizable

2020-12-20T16:40:06+00:00

Currently the size of the buffer to keep UEFI variables in memory is fixed
at 16384 bytes. This size has proven to be too small for some use cases.

Make the size of the memory buffer for UEFI variables customizable.

Reported-by: Paulo Alcantara (SUSE) 
Signed-off-by: Heinrich Schuchardt 
Acked-by: Ilias Apalodimas

efi_loader: remove empty comment line

2020-08-24T14:37:53+00:00

Remove a line leading to a warning in make htmldocs.

Signed-off-by: Heinrich Schuchardt

efi_loader: Enable run-time variable support for tee based variables

2020-08-01T09:57:41+00:00

We recently added functions for storing/restoring variables
from a file to a memory backed buffer marked as __efi_runtime_data
commit f1f990a8c958 ("efi_loader: memory buffer for variables")
commit 5f7dcf079de8 ("efi_loader: UEFI variable persistence")

Using the same idea we now can support GetVariable() and GetNextVariable()
on the OP-TEE based variables as well.

So let's re-arrange the code a bit and move the commmon code for
accessing variables out of efi_variable.c. Create common functions for
reading variables from memory that both implementations can use on
run-time. Then just use those functions in the run-time variants of the
OP-TEE based EFI variable implementation and initialize the memory
buffer on ExitBootServices()

Signed-off-by: Ilias Apalodimas 
Reviewed-by: Heinrich Schuchardt

efi_loader: describe EFI_VAR_FILE_MAGIC

2020-07-16T10:37:03+00:00

Add documentation for EFI_VAR_FILE_MAGIC used in the file format for UEFI
variables.

Signed-off-by: Heinrich Schuchardt

efi_loader: pre-seed UEFI variables

2020-07-16T10:37:02+00:00

Include a file with the initial values for non-volatile UEFI variables
into the U-Boot binary. If this variable is set, changes to variable PK
will not be allowed.

Signed-off-by: Heinrich Schuchardt

efi_loader: identify PK, KEK, db, dbx correctly

2020-07-16T10:37:02+00:00

To determine if a varible is on the of the authentication variables
PK, KEK, db, dbx we have to check both the name and the GUID.

Provide a function converting the variable-name/guid pair to an enum and
use it consistently.

Signed-off-by: Heinrich Schuchardt

efi_loader: restructure code for TEE variables

2020-07-16T10:37:02+00:00

When using secure boot functions needed both for file and TEE based UEFI
variables have to be moved to the common code module efi_var_common.c.

Signed-off-by: Heinrich Schuchardt

efi_loader: memory buffer for variables

2020-07-11T21:14:17+00:00

Saving UEFI variable as encoded U-Boot environment variables does not allow
support at runtime.

Provide functions to manage a memory buffer with UEFI variables.

Signed-off-by: Heinrich Schuchardt

efi_loader: UEFI variable persistence

2020-07-11T21:14:17+00:00

Persist non-volatile UEFI variables in a file on the EFI system partition.

The file is written whenever a non-volatile UEFI variable is changed after
initialization of the UEFI sub-system.

The file is read during the UEFI sub-system initialization to restore
non-volatile UEFI variables.

Signed-off-by: Heinrich Schuchardt