Skip to content
Commit 922b0375 authored by Albert Ou's avatar Albert Ou Committed by Paul Walmsley
Browse files

riscv: Fix memblock reservation for device tree blob



This fixes an error with how the FDT blob is reserved in memblock.
An incorrect physical address calculation exposed the FDT header to
unintended corruption, which typically manifested with of_fdt_raw_init()
faulting during late boot after fdt_totalsize() returned a wrong value.
Systems with smaller physical memory sizes more frequently trigger this
issue, as the kernel is more likely to allocate from the DMA32 zone
where bbl places the DTB after the kernel image.

Commit 671f9a3e ("RISC-V: Setup initial page tables in two stages")
changed the mapping of the DTB to reside in the fixmap area.
Consequently, early_init_fdt_reserve_self() cannot be used anymore in
setup_bootmem() since it relies on __pa() to derive a physical address,
which does not work with dtb_early_va that is no longer a valid kernel
logical address.

The reserved[0x1] region shows the effect of the pointer underflow
resulting from the __pa(initial_boot_params) offset subtraction:

[    0.000000] MEMBLOCK configuration:
[    0.000000]  memory size = 0x000000001fe00000 reserved size = 0x0000000000a2e514
[    0.000000]  memory.cnt  = 0x1
[    0.000000]  memory[0x0]     [0x0000000080200000-0x000000009fffffff], 0x000000001fe00000 bytes flags: 0x0
[    0.000000]  reserved.cnt  = 0x2
[    0.000000]  reserved[0x0]   [0x0000000080200000-0x0000000080c2dfeb], 0x0000000000a2dfec bytes flags: 0x0
[    0.000000]  reserved[0x1]   [0xfffffff080100000-0xfffffff080100527], 0x0000000000000528 bytes flags: 0x0

With the fix applied:

[    0.000000] MEMBLOCK configuration:
[    0.000000]  memory size = 0x000000001fe00000 reserved size = 0x0000000000a2e514
[    0.000000]  memory.cnt  = 0x1
[    0.000000]  memory[0x0]     [0x0000000080200000-0x000000009fffffff], 0x000000001fe00000 bytes flags: 0x0
[    0.000000]  reserved.cnt  = 0x2
[    0.000000]  reserved[0x0]   [0x0000000080200000-0x0000000080c2dfeb], 0x0000000000a2dfec bytes flags: 0x0
[    0.000000]  reserved[0x1]   [0x0000000080e00000-0x0000000080e00527], 0x0000000000000528 bytes flags: 0x0

Fixes: 671f9a3e ("RISC-V: Setup initial page tables in two stages")
Signed-off-by: default avatarAlbert Ou <aou@eecs.berkeley.edu>
Tested-by: default avatarBin Meng <bmeng.cn@gmail.com>
Reviewed-by: default avatarAnup Patel <anup@brainfault.org>
Signed-off-by: default avatarPaul Walmsley <paul.walmsley@sifive.com>
parent 18856604
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment