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Subject[PATCH 4.10 049/110] nios2: reserve boot memory for device tree
Date
4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tobias Klauser <tklauser@distanz.ch>

commit 921d701e6f31e1ffaca3560416af1aa04edb4c4f upstream.

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().

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/nios2/kernel/prom.c | 7 +++++++
arch/nios2/kernel/setup.c | 3 +++
2 files changed, 10 insertions(+)

--- a/arch/nios2/kernel/prom.c
+++ b/arch/nios2/kernel/prom.c
@@ -48,6 +48,13 @@ void * __init early_init_dt_alloc_memory
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;
--- a/arch/nios2/kernel/setup.c
+++ b/arch/nios2/kernel/setup.c
@@ -200,6 +200,9 @@ 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();

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