u-boot/lib/efi_loader/efi_var_mem.c
Ilias Apalodimas 53e54bf50d efi_loader: Avoid emitting efi_var_buf to .GOT
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.

<snip of efi_var_mem_find>

0000000000000084 <efi_var_mem_find>:
  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 <efi_var_mem_find>:
  b4:   aa0003ee    mov x14, x0
  b8:   9000000a    adrp    x10, 0 <efi_var_mem_compare>
            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: e01aed47d6 ("efi_loader: Enable run-time variable support for tee based variables")
Reported-by: Atish Patra <atishp@atishpatra.org>
Tested-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2021-01-20 08:17:17 +01:00

352 lines
8.3 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* File interface for UEFI variables
*
* Copyright (c) 2020, Heinrich Schuchardt
*/
#include <common.h>
#include <efi_loader.h>
#include <efi_variable.h>
#include <u-boot/crc.h>
/*
* The variables efi_var_file and efi_var_entry must be static to avoid
* referencing them via the global offset table (section .got). The GOT
* is neither mapped as EfiRuntimeServicesData nor do we support its
* relocation during SetVirtualAddressMap().
*/
static struct efi_var_file __efi_runtime_data *efi_var_buf;
static struct efi_var_entry __efi_runtime_data *efi_current_var;
/**
* efi_var_mem_compare() - compare GUID and name with a variable
*
* @var: variable to compare
* @guid: GUID to compare
* @name: variable name to compare
* @next: pointer to next variable
* Return: true if match
*/
static bool __efi_runtime
efi_var_mem_compare(struct efi_var_entry *var, const efi_guid_t *guid,
const u16 *name, struct efi_var_entry **next)
{
int i;
u8 *guid1, *guid2;
const u16 *data, *var_name;
bool match = true;
for (guid1 = (u8 *)&var->guid, guid2 = (u8 *)guid, i = 0;
i < sizeof(efi_guid_t) && match; ++i)
match = (guid1[i] == guid2[i]);
for (data = var->name, var_name = name;; ++data, ++var_name) {
if (match)
match = (*data == *var_name);
if (!*data)
break;
}
++data;
if (next)
*next = (struct efi_var_entry *)
ALIGN((uintptr_t)data + var->length, 8);
if (match)
efi_current_var = var;
return match;
}
struct efi_var_entry __efi_runtime
*efi_var_mem_find(const efi_guid_t *guid, const u16 *name,
struct efi_var_entry **next)
{
struct efi_var_entry *var, *last;
last = (struct efi_var_entry *)
((uintptr_t)efi_var_buf + efi_var_buf->length);
if (!*name) {
if (next) {
*next = efi_var_buf->var;
if (*next >= last)
*next = NULL;
}
return NULL;
}
if (efi_current_var &&
efi_var_mem_compare(efi_current_var, guid, name, next)) {
if (next && *next >= last)
*next = NULL;
return efi_current_var;
}
var = efi_var_buf->var;
if (var < last) {
for (; var;) {
struct efi_var_entry *pos;
bool match;
match = efi_var_mem_compare(var, guid, name, &pos);
if (pos >= last)
pos = NULL;
if (match) {
if (next)
*next = pos;
return var;
}
var = pos;
}
}
if (next)
*next = NULL;
return NULL;
}
void __efi_runtime efi_var_mem_del(struct efi_var_entry *var)
{
u16 *data;
struct efi_var_entry *next, *last;
if (!var)
return;
last = (struct efi_var_entry *)
((uintptr_t)efi_var_buf + efi_var_buf->length);
if (var <= efi_current_var)
efi_current_var = NULL;
for (data = var->name; *data; ++data)
;
++data;
next = (struct efi_var_entry *)
ALIGN((uintptr_t)data + var->length, 8);
efi_var_buf->length -= (uintptr_t)next - (uintptr_t)var;
/* efi_memcpy_runtime() can be used because next >= var. */
efi_memcpy_runtime(var, next, (uintptr_t)last - (uintptr_t)next);
efi_var_buf->crc32 = crc32(0, (u8 *)efi_var_buf->var,
efi_var_buf->length -
sizeof(struct efi_var_file));
}
efi_status_t __efi_runtime efi_var_mem_ins(
u16 *variable_name,
const efi_guid_t *vendor, u32 attributes,
const efi_uintn_t size1, const void *data1,
const efi_uintn_t size2, const void *data2,
const u64 time)
{
u16 *data;
struct efi_var_entry *var;
u32 var_name_len;
var = (struct efi_var_entry *)
((uintptr_t)efi_var_buf + efi_var_buf->length);
for (var_name_len = 0; variable_name[var_name_len]; ++var_name_len)
;
++var_name_len;
data = var->name + var_name_len;
if ((uintptr_t)data - (uintptr_t)efi_var_buf + size1 + size2 >
EFI_VAR_BUF_SIZE)
return EFI_OUT_OF_RESOURCES;
var->attr = attributes;
var->length = size1 + size2;
var->time = time;
efi_memcpy_runtime(&var->guid, vendor, sizeof(efi_guid_t));
efi_memcpy_runtime(var->name, variable_name,
sizeof(u16) * var_name_len);
efi_memcpy_runtime(data, data1, size1);
efi_memcpy_runtime((u8 *)data + size1, data2, size2);
var = (struct efi_var_entry *)
ALIGN((uintptr_t)data + var->length, 8);
efi_var_buf->length = (uintptr_t)var - (uintptr_t)efi_var_buf;
efi_var_buf->crc32 = crc32(0, (u8 *)efi_var_buf->var,
efi_var_buf->length -
sizeof(struct efi_var_file));
return EFI_SUCCESS;
}
u64 __efi_runtime efi_var_mem_free(void)
{
return EFI_VAR_BUF_SIZE - efi_var_buf->length -
sizeof(struct efi_var_entry);
}
/**
* efi_var_mem_bs_del() - delete boot service only variables
*/
static void efi_var_mem_bs_del(void)
{
struct efi_var_entry *var = efi_var_buf->var;
for (;;) {
struct efi_var_entry *last;
last = (struct efi_var_entry *)
((uintptr_t)efi_var_buf + efi_var_buf->length);
if (var >= last)
break;
if (var->attr & EFI_VARIABLE_RUNTIME_ACCESS) {
u16 *data;
/* skip variable */
for (data = var->name; *data; ++data)
;
++data;
var = (struct efi_var_entry *)
ALIGN((uintptr_t)data + var->length, 8);
} else {
/* delete variable */
efi_var_mem_del(var);
}
}
}
/**
* efi_var_mem_notify_exit_boot_services() - ExitBootService callback
*
* @event: callback event
* @context: callback context
*/
static void EFIAPI
efi_var_mem_notify_exit_boot_services(struct efi_event *event, void *context)
{
EFI_ENTRY("%p, %p", event, context);
/* Delete boot service only variables */
efi_var_mem_bs_del();
EFI_EXIT(EFI_SUCCESS);
}
/**
* efi_var_mem_notify_exit_boot_services() - SetVirtualMemoryMap callback
*
* @event: callback event
* @context: callback context
*/
static void EFIAPI __efi_runtime
efi_var_mem_notify_virtual_address_map(struct efi_event *event, void *context)
{
efi_convert_pointer(0, (void **)&efi_var_buf);
efi_current_var = NULL;
}
efi_status_t efi_var_mem_init(void)
{
u64 memory;
efi_status_t ret;
struct efi_event *event;
ret = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES,
EFI_RUNTIME_SERVICES_DATA,
efi_size_in_pages(EFI_VAR_BUF_SIZE),
&memory);
if (ret != EFI_SUCCESS)
return ret;
efi_var_buf = (struct efi_var_file *)(uintptr_t)memory;
memset(efi_var_buf, 0, EFI_VAR_BUF_SIZE);
efi_var_buf->magic = EFI_VAR_FILE_MAGIC;
efi_var_buf->length = (uintptr_t)efi_var_buf->var -
(uintptr_t)efi_var_buf;
/* crc32 for 0 bytes = 0 */
ret = efi_create_event(EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
efi_var_mem_notify_exit_boot_services, NULL,
NULL, &event);
if (ret != EFI_SUCCESS)
return ret;
ret = efi_create_event(EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE, TPL_CALLBACK,
efi_var_mem_notify_virtual_address_map, NULL,
NULL, &event);
if (ret != EFI_SUCCESS)
return ret;
return ret;
}
efi_status_t __efi_runtime
efi_get_variable_mem(u16 *variable_name, const efi_guid_t *vendor, u32 *attributes,
efi_uintn_t *data_size, void *data, u64 *timep)
{
efi_uintn_t old_size;
struct efi_var_entry *var;
u16 *pdata;
if (!variable_name || !vendor || !data_size)
return EFI_INVALID_PARAMETER;
var = efi_var_mem_find(vendor, variable_name, NULL);
if (!var)
return EFI_NOT_FOUND;
if (attributes)
*attributes = var->attr;
if (timep)
*timep = var->time;
old_size = *data_size;
*data_size = var->length;
if (old_size < var->length)
return EFI_BUFFER_TOO_SMALL;
if (!data)
return EFI_INVALID_PARAMETER;
for (pdata = var->name; *pdata; ++pdata)
;
++pdata;
efi_memcpy_runtime(data, pdata, var->length);
return EFI_SUCCESS;
}
efi_status_t __efi_runtime
efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
u16 *variable_name, efi_guid_t *vendor)
{
struct efi_var_entry *var;
efi_uintn_t old_size;
u16 *pdata;
if (!variable_name_size || !variable_name || !vendor)
return EFI_INVALID_PARAMETER;
if (u16_strnlen(variable_name, *variable_name_size) ==
*variable_name_size)
return EFI_INVALID_PARAMETER;
if (!efi_var_mem_find(vendor, variable_name, &var) && *variable_name)
return EFI_INVALID_PARAMETER;
if (!var)
return EFI_NOT_FOUND;
for (pdata = var->name; *pdata; ++pdata)
;
++pdata;
old_size = *variable_name_size;
*variable_name_size = (uintptr_t)pdata - (uintptr_t)var->name;
if (old_size < *variable_name_size)
return EFI_BUFFER_TOO_SMALL;
efi_memcpy_runtime(variable_name, var->name, *variable_name_size);
efi_memcpy_runtime(vendor, &var->guid, sizeof(efi_guid_t));
return EFI_SUCCESS;
}
void efi_var_buf_update(struct efi_var_file *var_buf)
{
memcpy(efi_var_buf, var_buf, EFI_VAR_BUF_SIZE);
}