Patch "nios2: reserve boot memory for device tree" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    nios2: reserve boot memory for device tree

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nios2-reserve-boot-memory-for-device-tree.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 921d701e6f31e1ffaca3560416af1aa04edb4c4f Mon Sep 17 00:00:00 2001
From: Tobias Klauser <tklauser@distanz.ch>
Date: Sun, 2 Apr 2017 20:08:04 -0700
Subject: nios2: reserve boot memory for device tree

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
@@ -195,6 +195,9 @@ 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();


Patches currently in stable-queue which might be from tklauser@distanz.ch are

queue-4.9/nios2-reserve-boot-memory-for-device-tree.patch