nios2: reserve boot memory for device tree

Make sure to reserve the boot memory for the flattened device tree.
Otherwise it might get overwritten, e.g. when initial_boot_params is
copied, leading to a corrupted FDT and a boot hang/crash:

  bootconsole [early0] enabled
  Early console on uart16650 initialized at 0xf8001600
  OF: fdt: Error -11 processing FDT
  Kernel panic - not syncing: setup_cpuinfo: No CPU found in devicetree!

  ---[ end Kernel panic - not syncing: setup_cpuinfo: No CPU found in devicetree!

Guenter Roeck says:

> I think I found the problem. In unflatten_and_copy_device_tree(), with added
> debug information:
>
> OF: fdt: initial_boot_params=c861e400, dt=c861f000 size=28874 (0x70ca)
>
> ... and then initial_boot_params is copied to dt, which results in corrupted
> fdt since the memory overlaps. Looks like the initial_boot_params memory
> is not reserved and (re-)allocated by early_init_dt_alloc_memory_arch().

Cc: stable@vger.kernel.org
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reference: http://lkml.kernel.org/r/20170226210338.GA19476@roeck-us.net
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Ley Foon Tan <ley.foon.tan@intel.com>

diff --git a/arch/nios2/kernel/prom.c b/arch/nios2/kernel/prom.c
index 367c5426157ba14dfe8799664c3f11dd6eb9c8a2..3901b80d442021e17e96e29f33cea2b1c28ec345 100644 (file)
--- a/arch/nios2/kernel/prom.c
+++ b/arch/nios2/kernel/prom.c
@@ -48,6 +48,13 @@ void * __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
        return alloc_bootmem_align(size, align);
 }
 
+int __init early_init_dt_reserve_memory_arch(phys_addr_t base, phys_addr_t size,
+                                            bool nomap)
+{
+       reserve_bootmem(base, size, BOOTMEM_DEFAULT);
+       return 0;
+}
+
 void __init early_init_devtree(void *params)
 {
        __be32 *dtb = (u32 *)__dtb_start;

diff --git a/arch/nios2/kernel/setup.c b/arch/nios2/kernel/setup.c
index 6e57ffa5db2769babe8c285f1e88e16fe13ed998..6044d9be28b4493323d362162e7e5ec6c56e1f33 100644 (file)
--- a/arch/nios2/kernel/setup.c
+++ b/arch/nios2/kernel/setup.c
@@ -201,6 +201,9 @@ void __init setup_arch(char **cmdline_p)
        }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+       early_init_fdt_reserve_self();
+       early_init_fdt_scan_reserved_mem();
+
        unflatten_and_copy_device_tree();
 
        setup_cpuinfo();