erebion/coreboot
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libpayload/arch/arm64/mmu: Fix missing CBMEM in used ranges

Browse source 
We use mmu_ranges to track the list of memory ranges and their types for
MMU initialization. We also keep track of used memory ranges in
usedmem_ranges, to avoid them from being re-allocated in
mmu_alloc_range().

The problem is, the CBMEM range (CB_MEM_TABLE) is added to mmu_ranges,
but is never marked as "used" in usedmem_ranges. This potentially causes
any allocation (for example the framebuffer) to overlap with CBMEM. This
issue is observed when DMA_DEFAULT_SIZE is reduced from 32MB to 1MB [1].
Prior to that change, because there isn't enough space above the
coreboot table (with the 4GB upper limit) to fit the 32MB requested
region, the DMA heap is always allocated *below* the coreboot table. And
because the coreboot table is usually the lowest within CBMEM, the DMA
heap region is allocated *below* the whole CBMEM, which happens the
avoid the issue.

Fix the bug by adding CB_MEM_TABLE ranges to usedmem_ranges. The ranges
in usedmem_ranges don't need to be combined because they are not for MMU
initialization (and there's only one CB_MEM_TABLE range).

[1] commit aedc177f00 ("libpayload: arm64: Reduce DMA allocator space to 1MB")

BUG=b:424107889
TEST=emerge-skywalker libpayload
BRANCH=none

Change-Id: Ie9ecafc17546e524253c60ab684ec10ff3495998
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88063
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Bartłomiej Grzesik <bgrzesik@google.com>
Reviewed-by: Jakub "Kuba" Czapiga <czapiga@google.com>
This commit is contained in:
Yu-Ping Wu 2025-06-12 09:43:12 +08:00 • committed by Matt DeVillier
commit b4f2a51533
1 changed files with 13 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

19
payloads/libpayload/arch/arm64/mmu.c
View file

@ -606,16 +606,23 @@ static void mmu_extract_ranges(struct memrange *cb_ranges,
/* Extract memory ranges to be mapped */
for (; i < ncb; i++) {
uint64_t base = cb_ranges[i].base;
uint64_t size = cb_ranges[i].size;
switch (cb_ranges[i].type) {
case CB_MEM_RAM:
case CB_MEM_TABLE:
if (prev_range && (prev_range->base + prev_range->size
== cb_ranges[i].base)) {
prev_range->size += cb_ranges[i].size;
/* Mark this memrange as used memory */
if (mmu_add_memrange(&usedmem_ranges, base, size,
TYPE_NORMAL_MEM) == NULL)
mmu_error();
__fallthrough;
case CB_MEM_RAM:
if (prev_range &&
prev_range->base + prev_range->size == base) {
prev_range->size += size;
} else {
prev_range = mmu_add_memrange(mmu_ranges,
cb_ranges[i].base,
cb_ranges[i].size,
base, size,
TYPE_NORMAL_MEM);
if (prev_range == NULL)
mmu_error();