| From df0dc6b82ff53967e4a162cd9d7125da5eff8d68 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Fri, 15 Jan 2021 11:45:44 +0000 |
| Subject: of/fdt: Make sure no-map does not remove already reserved regions |
| |
| From: Nicolas Boichat <drinkcat@chromium.org> |
| |
| [ Upstream commit 8a5a75e5e9e55de1cef5d83ca3589cb4899193ef ] |
| |
| If the device tree is incorrectly configured, and attempts to |
| define a "no-map" reserved memory that overlaps with the kernel |
| data/code, the kernel would crash quickly after boot, with no |
| obvious clue about the nature of the issue. |
| |
| For example, this would happen if we have the kernel mapped at |
| these addresses (from /proc/iomem): |
| 40000000-41ffffff : System RAM |
| 40080000-40dfffff : Kernel code |
| 40e00000-411fffff : reserved |
| 41200000-413e0fff : Kernel data |
| |
| And we declare a no-map shared-dma-pool region at a fixed address |
| within that range: |
| mem_reserved: mem_region { |
| compatible = "shared-dma-pool"; |
| reg = <0 0x40000000 0 0x01A00000>; |
| no-map; |
| }; |
| |
| To fix this, when removing memory regions at early boot (which is |
| what "no-map" regions do), we need to make sure that the memory |
| is not already reserved. If we do, __reserved_mem_reserve_reg |
| will throw an error: |
| [ 0.000000] OF: fdt: Reserved memory: failed to reserve memory |
| for node 'mem_region': base 0x0000000040000000, size 26 MiB |
| and the code that will try to use the region should also fail, |
| later on. |
| |
| We do not do anything for non-"no-map" regions, as memblock |
| explicitly allows reserved regions to overlap, and the commit |
| that this fixes removed the check for that precise reason. |
| |
| [ qperret: fixed conflicts caused by the usage of memblock_mark_nomap ] |
| |
| Fixes: 094cb98179f19b7 ("of/fdt: memblock_reserve /memreserve/ regions in the case of partial overlap") |
| Signed-off-by: Nicolas Boichat <drinkcat@chromium.org> |
| Reviewed-by: Stephen Boyd <swboyd@chromium.org> |
| Signed-off-by: Quentin Perret <qperret@google.com> |
| Link: https://lore.kernel.org/r/20210115114544.1830068-3-qperret@google.com |
| Signed-off-by: Rob Herring <robh@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/of/fdt.c | 10 +++++++++- |
| 1 file changed, 9 insertions(+), 1 deletion(-) |
| |
| diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c |
| index 427b534d60d2d..dcc1dd96911a9 100644 |
| --- a/drivers/of/fdt.c |
| +++ b/drivers/of/fdt.c |
| @@ -1146,8 +1146,16 @@ int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size) |
| int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base, |
| phys_addr_t size, bool nomap) |
| { |
| - if (nomap) |
| + if (nomap) { |
| + /* |
| + * If the memory is already reserved (by another region), we |
| + * should not allow it to be marked nomap. |
| + */ |
| + if (memblock_is_region_reserved(base, size)) |
| + return -EBUSY; |
| + |
| return memblock_mark_nomap(base, size); |
| + } |
| return memblock_reserve(base, size); |
| } |
| |
| -- |
| 2.27.0 |
| |