Merge branch '3.4-rc1' into android-tegra-nv-3.3-rebased

Change-Id: Ib3b69ffc5ac3e07c9cc44cc49e9142088eec477e
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

3 files changed, 276 insertions, 133 deletions

diff --git a/Documentation/powerpc/firmware-assisted-dump.txt b/Documentation/powerpc/firmware-assisted-dump.txt
new file mode 100644
index 000000000000..3007bc98af28
--- /dev/null
+++ b/Documentation/powerpc/firmware-assisted-dump.txt
@@ -0,0 +1,270 @@
+
+                   Firmware-Assisted Dump
+                   ------------------------
+                       July 2011
+
+The goal of firmware-assisted dump is to enable the dump of
+a crashed system, and to do so from a fully-reset system, and
+to minimize the total elapsed time until the system is back
+in production use.
+
+- Firmware assisted dump (fadump) infrastructure is intended to replace
+  the existing phyp assisted dump.
+- Fadump uses the same firmware interfaces and memory reservation model
+  as phyp assisted dump.
+- Unlike phyp dump, fadump exports the memory dump through /proc/vmcore
+  in the ELF format in the same way as kdump. This helps us reuse the
+  kdump infrastructure for dump capture and filtering.
+- Unlike phyp dump, userspace tool does not need to refer any sysfs
+  interface while reading /proc/vmcore.
+- Unlike phyp dump, fadump allows user to release all the memory reserved
+  for dump, with a single operation of echo 1 > /sys/kernel/fadump_release_mem.
+- Once enabled through kernel boot parameter, fadump can be
+  started/stopped through /sys/kernel/fadump_registered interface (see
+  sysfs files section below) and can be easily integrated with kdump
+  service start/stop init scripts.
+
+Comparing with kdump or other strategies, firmware-assisted
+dump offers several strong, practical advantages:
+
+-- Unlike kdump, the system has been reset, and loaded
+   with a fresh copy of the kernel.  In particular,
+   PCI and I/O devices have been reinitialized and are
+   in a clean, consistent state.
+-- Once the dump is copied out, the memory that held the dump
+   is immediately available to the running kernel. And therefore,
+   unlike kdump, fadump doesn't need a 2nd reboot to get back
+   the system to the production configuration.
+
+The above can only be accomplished by coordination with,
+and assistance from the Power firmware. The procedure is
+as follows:
+
+-- The first kernel registers the sections of memory with the
+   Power firmware for dump preservation during OS initialization.
+   These registered sections of memory are reserved by the first
+   kernel during early boot.
+
+-- When a system crashes, the Power firmware will save
+   the low memory (boot memory of size larger of 5% of system RAM
+   or 256MB) of RAM to the previous registered region. It will
+   also save system registers, and hardware PTE's.
+
+   NOTE: The term 'boot memory' means size of the low memory chunk
+         that is required for a kernel to boot successfully when
+         booted with restricted memory. By default, the boot memory
+         size will be the larger of 5% of system RAM or 256MB.
+         Alternatively, user can also specify boot memory size
+         through boot parameter 'fadump_reserve_mem=' which will
+         override the default calculated size. Use this option
+         if default boot memory size is not sufficient for second
+         kernel to boot successfully.
+
+-- After the low memory (boot memory) area has been saved, the
+   firmware will reset PCI and other hardware state.  It will
+   *not* clear the RAM. It will then launch the bootloader, as
+   normal.
+
+-- The freshly booted kernel will notice that there is a new
+   node (ibm,dump-kernel) in the device tree, indicating that
+   there is crash data available from a previous boot. During
+   the early boot OS will reserve rest of the memory above
+   boot memory size effectively booting with restricted memory
+   size. This will make sure that the second kernel will not
+   touch any of the dump memory area.
+
+-- User-space tools will read /proc/vmcore to obtain the contents
+   of memory, which holds the previous crashed kernel dump in ELF
+   format. The userspace tools may copy this info to disk, or
+   network, nas, san, iscsi, etc. as desired.
+
+-- Once the userspace tool is done saving dump, it will echo
+   '1' to /sys/kernel/fadump_release_mem to release the reserved
+   memory back to general use, except the memory required for
+   next firmware-assisted dump registration.
+
+   e.g.
+     # echo 1 > /sys/kernel/fadump_release_mem
+
+Please note that the firmware-assisted dump feature
+is only available on Power6 and above systems with recent
+firmware versions.
+
+Implementation details:
+----------------------
+
+During boot, a check is made to see if firmware supports
+this feature on that particular machine. If it does, then
+we check to see if an active dump is waiting for us. If yes
+then everything but boot memory size of RAM is reserved during
+early boot (See Fig. 2). This area is released once we finish
+collecting the dump from user land scripts (e.g. kdump scripts)
+that are run. If there is dump data, then the
+/sys/kernel/fadump_release_mem file is created, and the reserved
+memory is held.
+
+If there is no waiting dump data, then only the memory required
+to hold CPU state, HPTE region, boot memory dump and elfcore
+header, is reserved at the top of memory (see Fig. 1). This area
+is *not* released: this region will be kept permanently reserved,
+so that it can act as a receptacle for a copy of the boot memory
+content in addition to CPU state and HPTE region, in the case a
+crash does occur.
+
+  o Memory Reservation during first kernel
+
+  Low memory                                        Top of memory
+  0      boot memory size                                       |
+  |           |                       |<--Reserved dump area -->|
+  V           V                       |   Permanent Reservation V
+  +-----------+----------/ /----------+---+----+-----------+----+
+  |           |                       |CPU|HPTE|  DUMP     |ELF |
+  +-----------+----------/ /----------+---+----+-----------+----+
+        |                                           ^
+        |                                           |
+        \                                           /
+         -------------------------------------------
+          Boot memory content gets transferred to
+          reserved area by firmware at the time of
+          crash
+                   Fig. 1
+
+  o Memory Reservation during second kernel after crash
+
+  Low memory                                        Top of memory
+  0      boot memory size                                       |
+  |           |<------------- Reserved dump area ----------- -->|
+  V           V                                                 V
+  +-----------+----------/ /----------+---+----+-----------+----+
+  |           |                       |CPU|HPTE|  DUMP     |ELF |
+  +-----------+----------/ /----------+---+----+-----------+----+
+        |                                                    |
+        V                                                    V
+   Used by second                                    /proc/vmcore
+   kernel to boot
+                   Fig. 2
+
+Currently the dump will be copied from /proc/vmcore to a
+a new file upon user intervention. The dump data available through
+/proc/vmcore will be in ELF format. Hence the existing kdump
+infrastructure (kdump scripts) to save the dump works fine with
+minor modifications.
+
+The tools to examine the dump will be same as the ones
+used for kdump.
+
+How to enable firmware-assisted dump (fadump):
+-------------------------------------
+
+1. Set config option CONFIG_FA_DUMP=y and build kernel.
+2. Boot into linux kernel with 'fadump=on' kernel cmdline option.
+3. Optionally, user can also set 'fadump_reserve_mem=' kernel cmdline
+   to specify size of the memory to reserve for boot memory dump
+   preservation.
+
+NOTE: If firmware-assisted dump fails to reserve memory then it will
+   fallback to existing kdump mechanism if 'crashkernel=' option
+   is set at kernel cmdline.
+
+Sysfs/debugfs files:
+------------
+
+Firmware-assisted dump feature uses sysfs file system to hold
+the control files and debugfs file to display memory reserved region.
+
+Here is the list of files under kernel sysfs:
+
+ /sys/kernel/fadump_enabled
+
+    This is used to display the fadump status.
+    0 = fadump is disabled
+    1 = fadump is enabled
+
+    This interface can be used by kdump init scripts to identify if
+    fadump is enabled in the kernel and act accordingly.
+
+ /sys/kernel/fadump_registered
+
+    This is used to display the fadump registration status as well
+    as to control (start/stop) the fadump registration.
+    0 = fadump is not registered.
+    1 = fadump is registered and ready to handle system crash.
+
+    To register fadump echo 1 > /sys/kernel/fadump_registered and
+    echo 0 > /sys/kernel/fadump_registered for un-register and stop the
+    fadump. Once the fadump is un-registered, the system crash will not
+    be handled and vmcore will not be captured. This interface can be
+    easily integrated with kdump service start/stop.
+
+ /sys/kernel/fadump_release_mem
+
+    This file is available only when fadump is active during
+    second kernel. This is used to release the reserved memory
+    region that are held for saving crash dump. To release the
+    reserved memory echo 1 to it:
+
+    echo 1  > /sys/kernel/fadump_release_mem
+
+    After echo 1, the content of the /sys/kernel/debug/powerpc/fadump_region
+    file will change to reflect the new memory reservations.
+
+    The existing userspace tools (kdump infrastructure) can be easily
+    enhanced to use this interface to release the memory reserved for
+    dump and continue without 2nd reboot.
+
+Here is the list of files under powerpc debugfs:
+(Assuming debugfs is mounted on /sys/kernel/debug directory.)
+
+ /sys/kernel/debug/powerpc/fadump_region
+
+    This file shows the reserved memory regions if fadump is
+    enabled otherwise this file is empty. The output format
+    is:
+    <region>: [<start>-<end>] <reserved-size> bytes, Dumped: <dump-size>
+
+    e.g.
+    Contents when fadump is registered during first kernel
+
+    # cat /sys/kernel/debug/powerpc/fadump_region
+    CPU : [0x0000006ffb0000-0x0000006fff001f] 0x40020 bytes, Dumped: 0x0
+    HPTE: [0x0000006fff0020-0x0000006fff101f] 0x1000 bytes, Dumped: 0x0
+    DUMP: [0x0000006fff1020-0x0000007fff101f] 0x10000000 bytes, Dumped: 0x0
+
+    Contents when fadump is active during second kernel
+
+    # cat /sys/kernel/debug/powerpc/fadump_region
+    CPU : [0x0000006ffb0000-0x0000006fff001f] 0x40020 bytes, Dumped: 0x40020
+    HPTE: [0x0000006fff0020-0x0000006fff101f] 0x1000 bytes, Dumped: 0x1000
+    DUMP: [0x0000006fff1020-0x0000007fff101f] 0x10000000 bytes, Dumped: 0x10000000
+        : [0x00000010000000-0x0000006ffaffff] 0x5ffb0000 bytes, Dumped: 0x5ffb0000
+
+NOTE: Please refer to Documentation/filesystems/debugfs.txt on
+      how to mount the debugfs filesystem.
+
+
+TODO:
+-----
+ o Need to come up with the better approach to find out more
+   accurate boot memory size that is required for a kernel to
+   boot successfully when booted with restricted memory.
+ o The fadump implementation introduces a fadump crash info structure
+   in the scratch area before the ELF core header. The idea of introducing
+   this structure is to pass some important crash info data to the second
+   kernel which will help second kernel to populate ELF core header with
+   correct data before it gets exported through /proc/vmcore. The current
+   design implementation does not address a possibility of introducing
+   additional fields (in future) to this structure without affecting
+   compatibility. Need to come up with the better approach to address this.
+   The possible approaches are:
+	1. Introduce version field for version tracking, bump up the version
+	whenever a new field is added to the structure in future. The version
+	field can be used to find out what fields are valid for the current
+	version of the structure.
+	2. Reserve the area of predefined size (say PAGE_SIZE) for this
+	structure and have unused area as reserved (initialized to zero)
+	for future field additions.
+   The advantage of approach 1 over 2 is we don't need to reserve extra space.
+---
+Author: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
+This document is based on the original documentation written for phyp
+assisted dump by Linas Vepstas and Manish Ahuja.
diff --git a/Documentation/powerpc/mpc52xx.txt b/Documentation/powerpc/mpc52xx.txt
index 10dd4ab93b85..0d540a31ea1a 100644
--- a/Documentation/powerpc/mpc52xx.txt
+++ b/Documentation/powerpc/mpc52xx.txt
@@ -2,7 +2,7 @@ Linux 2.6.x on MPC52xx family
 -----------------------------
 
 For the latest info, go to http://www.246tNt.com/mpc52xx/
- 
+
 To compile/use :
 
   - U-Boot:
@@ -10,23 +10,23 @@ To compile/use :
         if you wish to ).
      # make lite5200_defconfig
      # make uImage
-    
+
      then, on U-boot:
      => tftpboot 200000 uImage
      => tftpboot 400000 pRamdisk
      => bootm 200000 400000
-    
+
   - DBug:
      # <edit Makefile to set ARCH=ppc & CROSS_COMPILE=... ( also EXTRAVERSION
         if you wish to ).
      # make lite5200_defconfig
      # cp your_initrd.gz arch/ppc/boot/images/ramdisk.image.gz
-     # make zImage.initrd 
-     # make 
+     # make zImage.initrd
+     # make
 
      then in DBug:
      DBug> dn -i zImage.initrd.lite5200
-     
+
 
 Some remarks :
  - The port is named mpc52xxx, and config options are PPC_MPC52xx. The MGT5100
diff --git a/Documentation/powerpc/phyp-assisted-dump.txt b/Documentation/powerpc/phyp-assisted-dump.txt
deleted file mode 100644
index ad340205d96a..000000000000
--- a/Documentation/powerpc/phyp-assisted-dump.txt
+++ /dev/null
@@ -1,127 +0,0 @@
-
-                   Hypervisor-Assisted Dump
-                   ------------------------
-                       November 2007
-
-The goal of hypervisor-assisted dump is to enable the dump of
-a crashed system, and to do so from a fully-reset system, and
-to minimize the total elapsed time until the system is back
-in production use.
-
-As compared to kdump or other strategies, hypervisor-assisted
-dump offers several strong, practical advantages:
-
--- Unlike kdump, the system has been reset, and loaded
-   with a fresh copy of the kernel.  In particular,
-   PCI and I/O devices have been reinitialized and are
-   in a clean, consistent state.
--- As the dump is performed, the dumped memory becomes
-   immediately available to the system for normal use.
--- After the dump is completed, no further reboots are
-   required; the system will be fully usable, and running
-   in its normal, production mode on its normal kernel.
-
-The above can only be accomplished by coordination with,
-and assistance from the hypervisor. The procedure is
-as follows:
-
--- When a system crashes, the hypervisor will save
-   the low 256MB of RAM to a previously registered
-   save region. It will also save system state, system
-   registers, and hardware PTE's.
-
--- After the low 256MB area has been saved, the
-   hypervisor will reset PCI and other hardware state.
-   It will *not* clear RAM. It will then launch the
-   bootloader, as normal.
-
--- The freshly booted kernel will notice that there
-   is a new node (ibm,dump-kernel) in the device tree,
-   indicating that there is crash data available from
-   a previous boot. It will boot into only 256MB of RAM,
-   reserving the rest of system memory.
-
--- Userspace tools will parse /sys/kernel/release_region
-   and read /proc/vmcore to obtain the contents of memory,
-   which holds the previous crashed kernel. The userspace
-   tools may copy this info to disk, or network, nas, san,
-   iscsi, etc. as desired.
-
-   For Example: the values in /sys/kernel/release-region
-   would look something like this (address-range pairs).
-   CPU:0x177fee000-0x10000: HPTE:0x177ffe020-0x1000: /
-   DUMP:0x177fff020-0x10000000, 0x10000000-0x16F1D370A
-
--- As the userspace tools complete saving a portion of
-   dump, they echo an offset and size to
-   /sys/kernel/release_region to release the reserved
-   memory back to general use.
-
-   An example of this is:
-     "echo 0x40000000 0x10000000 > /sys/kernel/release_region"
-   which will release 256MB at the 1GB boundary.
-
-Please note that the hypervisor-assisted dump feature
-is only available on Power6-based systems with recent
-firmware versions.
-
-Implementation details:
-----------------------
-
-During boot, a check is made to see if firmware supports
-this feature on this particular machine. If it does, then
-we check to see if a active dump is waiting for us. If yes
-then everything but 256 MB of RAM is reserved during early
-boot. This area is released once we collect a dump from user
-land scripts that are run. If there is dump data, then
-the /sys/kernel/release_region file is created, and
-the reserved memory is held.
-
-If there is no waiting dump data, then only the highest
-256MB of the ram is reserved as a scratch area. This area
-is *not* released: this region will be kept permanently
-reserved, so that it can act as a receptacle for a copy
-of the low 256MB in the case a crash does occur. See,
-however, "open issues" below, as to whether
-such a reserved region is really needed.
-
-Currently the dump will be copied from /proc/vmcore to a
-a new file upon user intervention. The starting address
-to be read and the range for each data point in provided
-in /sys/kernel/release_region.
-
-The tools to examine the dump will be same as the ones
-used for kdump.
-
-General notes:
---------------
-Security: please note that there are potential security issues
-with any sort of dump mechanism. In particular, plaintext
-(unencrypted) data, and possibly passwords, may be present in
-the dump data. Userspace tools must take adequate precautions to
-preserve security.
-
-Open issues/ToDo:
-------------
- o The various code paths that tell the hypervisor that a crash
-   occurred, vs. it simply being a normal reboot, should be
-   reviewed, and possibly clarified/fixed.
-
- o Instead of using /sys/kernel, should there be a /sys/dump
-   instead? There is a dump_subsys being created by the s390 code,
-   perhaps the pseries code should use a similar layout as well.
-
- o Is reserving a 256MB region really required? The goal of
-   reserving a 256MB scratch area is to make sure that no
-   important crash data is clobbered when the hypervisor
-   save low mem to the scratch area. But, if one could assure
-   that nothing important is located in some 256MB area, then
-   it would not need to be reserved. Something that can be
-   improved in subsequent versions.
-
- o Still working the kdump team to integrate this with kdump,
-   some work remains but this would not affect the current
-   patches.
-
- o Still need to write a shell script, to copy the dump away.
-   Currently I am parsing it manually.