| Age | Commit message (Collapse) | Author | Files | Lines |
|---|
|
This patch adds the device nodes for the DISP function blocks
comprising the display subsystem.
Signed-off-by: CK Hu <[email protected]>
Signed-off-by: Cawa Cheng <[email protected]>
Signed-off-by: Jie Qiu <[email protected]>
Signed-off-by: Daniel Kurtz <[email protected]>
Signed-off-by: Philipp Zabel <[email protected]>
Signed-off-by: Matthias Brugger <[email protected]>
|
|
Update DTSI file to add the reset controller node.
Signed-off-by: Neil Armstrong <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Add node for ethernet interface and pinctrl pins.
Enable on odroid-C2 and P20x boards.
Acked-by: Carlo Caione <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Add DT nodes for additional UARTs (UART B & C in EE domain) and add pins
for all EE domain UARTs.
Acked-by: Carlo Caione <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Acked-by: Carlo Caione <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Update DTS and DTSI files to enable the pin controller. We also now
support the blinking blue LED on the Odroid-C2.
Signed-off-by: Carlo Caione <[email protected]>
Acked-by: Linus Walleij <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Add the two new compatibles for the Amlogic Meson GXBB pin controllers.
Signed-off-by: Carlo Caione <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Add two new buses in the DTS: hiu and periphs buses.
In the Amlogic S905/GXBB SoC several devices (clock / eth / pin
controllers, etc...) are mapped under these two buses. Add them in the
DT before starting to add new devices.
Signed-off-by: Carlo Caione <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
|
|
Add support to the Northstar 2 Device tree file for the ARM CCI-400 PMU.
Signed-off-by: Jon Mason <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
Add all of the UARTs present on NS2 and enable them in the SVK device
tree file. Also, do some magic to make sure that uart3 is discovered as
ttyS0 (as that is the console UART).
Signed-off-by: Jon Mason <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
This enables the GPIO support for Broadcom NS2 SoC
Signed-off-by: Yendapally Reddy Dhananjaya Reddy <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
This enables the pinctrl support for Broadcom NS2 SoC
Signed-off-by: Yendapally Reddy Dhananjaya Reddy <[email protected]>
Reviewed-by: Ray Jui <[email protected]>
Acked-by: Linus Walleij <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
We have one dual-port SATA3 AHCI controller present in
NS2 SoC.
This patch enables SATA3 AHCI controller and SATA3 PHY
for NS2 SoC in NS2 DT.
Signed-off-by: Anup Patel <[email protected]>
Reviewed-by: Ray Jui <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
The Broadcom iProc SoCs have AHCI compliant SATA controller. This
patch adds common compatible string for AHCI SATA controller on
iProc SoCs.
Signed-off-by: Anup Patel <[email protected]>
Acked-by: Rob Herring <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
|
|
The hub and the ethernet in its port 1 are hardwired on the board.
Compared to the adapters that can be plugged into the USB ports, this
one has no serial EEPROM to store its MAC. Nevertheless, the Raspberry Pi
has the MAC address for this adapter in its ROM, accessible from its
firmware.
U-Boot can read out the address and set the local-mac-address property of the
node with "ethernet" alias. Let's add the node so that U-Boot can do its
business.
Model B rev2 and Model B+ entries were verified by me, the hierarchy and
pid/vid pair for the Version 2 was provided by Peter Chen. Original
Model B is a blind shot, though very likely correct.
Signed-off-by: Lubomir Rintel <[email protected]>
Acked-by: Stephen Warren <[email protected]>
Signed-off-by: Eric Anholt <[email protected]>
|
|
Add the core io-domain nodes to grf and pmugrf which individual
boards than just have to enable and add the necessary supplies to.
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
Add the supply-links according to the R88 schematics.
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
Add the core io-domain nodes to grf and pmugrf which individual
boards than just have to enable and add the necessary supplies to.
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
The general register files do contain a lot of separate functions and
while some really are only registers with a lot of different 1-bit
settings, there are also a lot of them containing some bigger function
blocks. To be able to define these as sub-devices, make them simple-mfds.
Signed-off-by: Heiko Stuebner <[email protected]>
Tested-by: David Wu <[email protected]>
|
|
Rockchip's rk3399 evaluation board has eMMC. Let's enable the
newly-added nodes.
Signed-off-by: Brian Norris <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
Add description for the SDHCI v5.1 eMMC controller on rk3399. Fix it to
200 MHz, to support all supported timing modes.
Note that 'rockchip,rk3399-sdhci-5.1' is not documented; we presumably
have a compliant Arasan controller, but let's have a rockchip property
as the canonical backup/precautionary measure. Per Heiko's previous
suggestion, let's not clutter the arasan doc with it.
Signed-off-by: Brian Norris <[email protected]>
Reviewed-by: Shawn Lin <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
Per the examples in
Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt, we need the
grf node to be a simple-mfd in order to properly enumerate child devices
like our eMMC PHY.
Signed-off-by: Brian Norris <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
[directly mimic for the pmugrf, which will need the same change later
and there is no need to pollute commit history with another patch]
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
These clocks are all core clocks used by many blocks/peripherals, many
of whose drivers don't set their clock rates at all. Let's assign
reasonable default clock rates for these core clocks, so that these
peripherals get something reasonable by default, and also so that if
child devices want to select a clock rate themselves, their muxes have
some reasonable parent clock rates to branch off of (rather than just
the boot-time defaults).
This helps the eMMC PHY, for one, to get a reasonable ACLK rate.
Signed-off-by: Xing Zheng <[email protected]>
Signed-off-by: Brian Norris <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Signed-off-by: Heiko Stuebner <[email protected]>
|
|
Drop 0x from unit address of gic as this is the desired form for
a unit address.
Signed-off-by: Simon Horman <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
|
|
Warning (unit_address_vs_reg): Node /regulator@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /regulator@2 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /regulator@3 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /regulator@4 has a unit name, but no reg property
Signed-off-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
Warning (unit_address_vs_reg): Node /cache-controller@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /cache-controller@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,dvc/dvc@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,dvc/dvc@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@2 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@3 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@4 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@5 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@6 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@7 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@8 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,src/src@9 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@0 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@1 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@2 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@3 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@4 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@5 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@6 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@7 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@8 has a unit name, but no reg property
Warning (unit_address_vs_reg): Node /soc/sound@ec500000/rcar_sound,ssi/ssi@9 has a unit name, but no reg property
Move the cache-controller nodes under the cpus node, and make their unit
names and reg properties match the MPIDR values.
Signed-off-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
Hook up the RWDT device node to the SYSC "always-on" PM Domain, for a
more consistent device-power-area description in DT.
Cfr. commit 38dbb45ee4bc ("arm64: dts: r8a7795: Use SYSC "always-on" PM
Domain")
Fixes: f43838a7ae014cba ("arm64: dts: r8a7795: Add RWDT node")
Signed-off-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
This patch enables watchdog timer for Salvator-X board.
Signed-off-by: Takeshi Kihara <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Acked-by: Guenter Roeck <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
This patch adds the RWDT device node for r8a7795.
Signed-off-by: Takeshi Kihara <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Acked-by: Guenter Roeck <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
Add DMA properties to the I2C nodes.
Signed-off-by: Niklas Söderlund <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
There are some requirements about the GIC-400 memory layout and its
mapping if using 64k aligned base addresses like on r8a7795.
See e.g.
http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=21550029f709072aacf3b9
Map the whole memory range instead of only 0x2000. This will fix
the issue that some hypervisors, e.g. Xen, fail to handle the
interrupts correctly.
Signed-off-by: Pooya Keshavarzi <[email protected]>
Signed-off-by: Dirk Behme <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
On the Salvator-X development board, the RTS and CTS pins of debug
serial-1 port SCIF1 are wired to the CP2102 Serial-USB bridge. Reflect
this in the DTS by adding the "uart-has-rtscts" property to the scif1
device node.
Signed-off-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Simon Horman <[email protected]>
|
|
|
|
The self-test was updated to cover zero-length strings; the function
needs to be updated, too.
Reported-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: George Spelvin <[email protected]>
Fixes: fcfd2fbf22d2 ("fs/namei.c: Add hashlen_string() function")
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The original name was simply hash_string(), but that conflicted with a
function with that name in drivers/base/power/trace.c, and I decided
that calling it "hashlen_" was better anyway.
But you have to do it in two places.
[ This caused build errors for architectures that don't define
CONFIG_DCACHE_WORD_ACCESS - Linus ]
Signed-off-by: George Spelvin <[email protected]>
Reported-by: Guenter Roeck <[email protected]>
Fixes: fcfd2fbf22d2 ("fs/namei.c: Add hashlen_string() function")
Signed-off-by: Linus Torvalds <[email protected]>
|
|
The HPFS filesystem used generic_show_options to produce string that is
displayed in /proc/mounts. However, there is a problem that the options
may disappear after remount. If we mount the filesystem with option1
and then remount it with option2, /proc/mounts should show both option1
and option2, however it only shows option2 because the whole option
string is replaced with replace_mount_options in hpfs_remount_fs.
To fix this bug, implement the hpfs_show_options function that prints
options that are currently selected.
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Commit c8f33d0bec99 ("affs: kstrdup() memory handling") checks if the
kstrdup function returns NULL due to out-of-memory condition.
However, if we are remounting a filesystem with no change to
filesystem-specific options, the parameter data is NULL. In this case,
kstrdup returns NULL (because it was passed NULL parameter), although no
out of memory condition exists. The mount syscall then fails with
ENOMEM.
This patch fixes the bug. We fail with ENOMEM only if data is non-NULL.
The patch also changes the call to replace_mount_options - if we didn't
pass any filesystem-specific options, we don't call
replace_mount_options (thus we don't erase existing reported options).
Fixes: c8f33d0bec99 ("affs: kstrdup() memory handling")
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected] # v4.1+
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Commit ce657611baf9 ("hpfs: kstrdup() out of memory handling") checks if
the kstrdup function returns NULL due to out-of-memory condition.
However, if we are remounting a filesystem with no change to
filesystem-specific options, the parameter data is NULL. In this case,
kstrdup returns NULL (because it was passed NULL parameter), although no
out of memory condition exists. The mount syscall then fails with
ENOMEM.
This patch fixes the bug. We fail with ENOMEM only if data is non-NULL.
The patch also changes the call to replace_mount_options - if we didn't
pass any filesystem-specific options, we don't call
replace_mount_options (thus we don't erase existing reported options).
Fixes: ce657611baf9 ("hpfs: kstrdup() out of memory handling")
Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected]
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Pull more MIPS updates from Ralf Baechle:
"This is the secondnd batch of MIPS patches for 4.7. Summary:
CPS:
- Copy EVA configuration when starting secondary VPs.
EIC:
- Clear Status IPL.
Lasat:
- Fix a few off by one bugs.
lib:
- Mark intrinsics notrace. Not only are the intrinsics
uninteresting, it would cause infinite recursion.
MAINTAINERS:
- Add file patterns for MIPS BRCM device tree bindings.
- Add file patterns for mips device tree bindings.
MT7628:
- Fix MT7628 pinmux typos.
- wled_an pinmux gpio.
- EPHY LEDs pinmux support.
Pistachio:
- Enable KASLR
VDSO:
- Build microMIPS VDSO for microMIPS kernels.
- Fix aliasing warning by building with `-fno-strict-aliasing' for
debugging but also tracing them might result in recursion.
Misc:
- Add missing FROZEN hotplug notifier transitions.
- Fix clk binding example for varioius PIC32 devices.
- Fix cpu interrupt controller node-names in the DT files.
- Fix XPA CPU feature separation.
- Fix write_gc0_* macros when writing zero.
- Add inline asm encoding helpers.
- Add missing VZ accessor microMIPS encodings.
- Fix little endian microMIPS MSA encodings.
- Add 64-bit HTW fields and fix its configuration.
- Fix sigreturn via VDSO on microMIPS kernel.
- Lots of typo fixes.
- Add definitions of SegCtl registers and use them"
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (49 commits)
MIPS: Add missing FROZEN hotplug notifier transitions
MIPS: Build microMIPS VDSO for microMIPS kernels
MIPS: Fix sigreturn via VDSO on microMIPS kernel
MIPS: devicetree: fix cpu interrupt controller node-names
MIPS: VDSO: Build with `-fno-strict-aliasing'
MIPS: Pistachio: Enable KASLR
MIPS: lib: Mark intrinsics notrace
MIPS: Fix 64-bit HTW configuration
MIPS: Add 64-bit HTW fields
MAINTAINERS: Add file patterns for mips device tree bindings
MAINTAINERS: Add file patterns for mips brcm device tree bindings
MIPS: Simplify DSP instruction encoding macros
MIPS: Add missing tlbinvf/XPA microMIPS encodings
MIPS: Fix little endian microMIPS MSA encodings
MIPS: Add missing VZ accessor microMIPS encodings
MIPS: Add inline asm encoding helpers
MIPS: Spelling fix lets -> let's
MIPS: VR41xx: Fix typo
MIPS: oprofile: Fix typo
MIPS: math-emu: Fix typo
...
|
|
Various builds (such as i386:allmodconfig) fail with
fs/binfmt_aout.c:133:2: error: expected identifier or '(' before 'return'
fs/binfmt_aout.c:134:1: error: expected identifier or '(' before '}' token
[ Oops. My bad, I had stupidly thought that "allmodconfig" covered this
on x86-64 too, but it obviously doesn't. Egg on my face. - Linus ]
Fixes: 5d22fc25d4fc ("mm: remove more IS_ERR_VALUE abuses")
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
|
|
Pull string hash improvements from George Spelvin:
"This series does several related things:
- Makes the dcache hash (fs/namei.c) useful for general kernel use.
(Thanks to Bruce for noticing the zero-length corner case)
- Converts the string hashes in <linux/sunrpc/svcauth.h> to use the
above.
- Avoids 64-bit multiplies in hash_64() on 32-bit platforms. Two
32-bit multiplies will do well enough.
- Rids the world of the bad hash multipliers in hash_32.
This finishes the job started in commit 689de1d6ca95 ("Minimal
fix-up of bad hashing behavior of hash_64()")
The vast majority of Linux architectures have hardware support for
32x32-bit multiply and so derive no benefit from "simplified"
multipliers.
The few processors that do not (68000, h8/300 and some models of
Microblaze) have arch-specific implementations added. Those
patches are last in the series.
- Overhauls the dcache hash mixing.
The patch in commit 0fed3ac866ea ("namei: Improve hash mixing if
CONFIG_DCACHE_WORD_ACCESS") was an off-the-cuff suggestion.
Replaced with a much more careful design that's simultaneously
faster and better. (My own invention, as there was noting suitable
in the literature I could find. Comments welcome!)
- Modify the hash_name() loop to skip the initial HASH_MIX(). This
would let us salt the hash if we ever wanted to.
- Sort out partial_name_hash().
The hash function is declared as using a long state, even though
it's truncated to 32 bits at the end and the extra internal state
contributes nothing to the result. And some callers do odd things:
- fs/hfs/string.c only allocates 32 bits of state
- fs/hfsplus/unicode.c uses it to hash 16-bit unicode symbols not bytes
- Modify bytemask_from_count to handle inputs of 1..sizeof(long)
rather than 0..sizeof(long)-1. This would simplify users other
than full_name_hash"
Special thanks to Bruce Fields for testing and finding bugs in v1. (I
learned some humbling lessons about "obviously correct" code.)
On the arch-specific front, the m68k assembly has been tested in a
standalone test harness, I've been in contact with the Microblaze
maintainers who mostly don't care, as the hardware multiplier is never
omitted in real-world applications, and I haven't heard anything from
the H8/300 world"
* 'hash' of git://ftp.sciencehorizons.net/linux:
h8300: Add <asm/hash.h>
microblaze: Add <asm/hash.h>
m68k: Add <asm/hash.h>
<linux/hash.h>: Add support for architecture-specific functions
fs/namei.c: Improve dcache hash function
Eliminate bad hash multipliers from hash_32() and hash_64()
Change hash_64() return value to 32 bits
<linux/sunrpc/svcauth.h>: Define hash_str() in terms of hashlen_string()
fs/namei.c: Add hashlen_string() function
Pull out string hash to <linux/stringhash.h>
|
|
This will improve the performance of hash_32() and hash_64(), but due
to complete lack of multi-bit shift instructions on H8, performance will
still be bad in surrounding code.
Designing H8-specific hash algorithms to work around that is a separate
project. (But if the maintainers would like to get in touch...)
Signed-off-by: George Spelvin <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: [email protected]
|
|
Microblaze is an FPGA soft core that can be configured various ways.
If it is configured without a multiplier, the standard __hash_32()
will require a call to __mulsi3, which is a slow software loop.
Instead, use a shift-and-add sequence for the constant multiply.
GCC knows how to do this, but it's not as clever as some.
Signed-off-by: George Spelvin <[email protected]>
Cc: Alistair Francis <[email protected]>
Cc: Michal Simek <[email protected]>
|
|
This provides a multiply by constant GOLDEN_RATIO_32 = 0x61C88647
for the original mc68000, which lacks a 32x32-bit multiply instruction.
Yes, the amount of optimization effort put in is excessive. :-)
Shift-add chain found by Yevgen Voronenko's Hcub algorithm at
http://spiral.ece.cmu.edu/mcm/gen.html
Signed-off-by: George Spelvin <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Andreas Schwab <[email protected]>
Cc: Philippe De Muyter <[email protected]>
Cc: [email protected]
|
|
This is just the infrastructure; there are no users yet.
This is modelled on CONFIG_ARCH_RANDOM; a CONFIG_ symbol declares
the existence of <asm/hash.h>.
That file may define its own versions of various functions, and define
HAVE_* symbols (no CONFIG_ prefix!) to suppress the generic ones.
Included is a self-test (in lib/test_hash.c) that verifies the basics.
It is NOT in general required that the arch-specific functions compute
the same thing as the generic, but if a HAVE_* symbol is defined with
the value 1, then equality is tested.
Signed-off-by: George Spelvin <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Andreas Schwab <[email protected]>
Cc: Philippe De Muyter <[email protected]>
Cc: [email protected]
Cc: Alistair Francis <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Yoshinori Sato <[email protected]>
Cc: [email protected]
|
|
Patch 0fed3ac866 improved the hash mixing, but the function is slower
than necessary; there's a 7-instruction dependency chain (10 on x86)
each loop iteration.
Word-at-a-time access is a very tight loop (which is good, because
link_path_walk() is one of the hottest code paths in the entire kernel),
and the hash mixing function must not have a longer latency to avoid
slowing it down.
There do not appear to be any published fast hash functions that:
1) Operate on the input a word at a time, and
2) Don't need to know the length of the input beforehand, and
3) Have a single iterated mixing function, not needing conditional
branches or unrolling to distinguish different loop iterations.
One of the algorithms which comes closest is Yann Collet's xxHash, but
that's two dependent multiplies per word, which is too much.
The key insights in this design are:
1) Barring expensive ops like multiplies, to diffuse one input bit
across 64 bits of hash state takes at least log2(64) = 6 sequentially
dependent instructions. That is more cycles than we'd like.
2) An operation like "hash ^= hash << 13" requires a second temporary
register anyway, and on a 2-operand machine like x86, it's three
instructions.
3) A better use of a second register is to hold a two-word hash state.
With careful design, no temporaries are needed at all, so it doesn't
increase register pressure. And this gets rid of register copying
on 2-operand machines, so the code is smaller and faster.
4) Using two words of state weakens the requirement for one-round mixing;
we now have two rounds of mixing before cancellation is possible.
5) A two-word hash state also allows operations on both halves to be
done in parallel, so on a superscalar processor we get more mixing
in fewer cycles.
I ended up using a mixing function inspired by the ChaCha and Speck
round functions. It is 6 simple instructions and 3 cycles per iteration
(assuming multiply by 9 can be done by an "lea" instruction):
x ^= *input++;
y ^= x; x = ROL(x, K1);
x += y; y = ROL(y, K2);
y *= 9;
Not only is this reversible, two consecutive rounds are reversible:
if you are given the initial and final states, but not the intermediate
state, it is possible to compute both input words. This means that at
least 3 words of input are required to create a collision.
(It also has the property, used by hash_name() to avoid a branch, that
it hashes all-zero to all-zero.)
The rotate constants K1 and K2 were found by experiment. The search took
a sample of random initial states (I used 1023) and considered the effect
of flipping each of the 64 input bits on each of the 128 output bits two
rounds later. Each of the 8192 pairs can be considered a biased coin, and
adding up the Shannon entropy of all of them produces a score.
The best-scoring shifts also did well in other tests (flipping bits in y,
trying 3 or 4 rounds of mixing, flipping all 64*63/2 pairs of input bits),
so the choice was made with the additional constraint that the sum of the
shifts is odd and not too close to the word size.
The final state is then folded into a 32-bit hash value by a less carefully
optimized multiply-based scheme. This also has to be fast, as pathname
components tend to be short (the most common case is one iteration!), but
there's some room for latency, as there is a fair bit of intervening logic
before the hash value is used for anything.
(Performance verified with "bonnie++ -s 0 -n 1536:-2" on tmpfs. I need
a better benchmark; the numbers seem to show a slight dip in performance
between 4.6.0 and this patch, but they're too noisy to quote.)
Special thanks to Bruce fields for diligent testing which uncovered a
nasty fencepost error in an earlier version of this patch.
[checkpatch.pl formatting complaints noted and respectfully disagreed with.]
Signed-off-by: George Spelvin <[email protected]>
Tested-by: J. Bruce Fields <[email protected]>
|
|
The "simplified" prime multipliers made very bad hash functions, so get rid
of them. This completes the work of 689de1d6ca.
To avoid the inefficiency which was the motivation for the "simplified"
multipliers, hash_64() on 32-bit systems is changed to use a different
algorithm. It makes two calls to hash_32() instead.
drivers/media/usb/dvb-usb-v2/af9015.c uses the old GOLDEN_RATIO_PRIME_32
for some horrible reason, so it inherits a copy of the old definition.
Signed-off-by: George Spelvin <[email protected]>
Cc: Antti Palosaari <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
|
|
That's all that's ever asked for, and it makes the return
type of hash_long() consistent.
It also allows (upcoming patch) an optimized implementation
of hash_64 on 32-bit machines.
I tried adding a BUILD_BUG_ON to ensure the number of bits requested
was never more than 32 (most callers use a compile-time constant), but
adding <linux/bug.h> to <linux/hash.h> breaks the tools/perf compiler
unless tools/perf/MANIFEST is updated, and understanding that code base
well enough to update it is too much trouble. I did the rest of an
allyesconfig build with such a check, and nothing tripped.
Signed-off-by: George Spelvin <[email protected]>
|
|
Finally, the first use of previous two patches: eliminate the
separate ad-hoc string hash functions in the sunrpc code.
Now hash_str() is a wrapper around hash_string(), and hash_mem() is
likewise a wrapper around full_name_hash().
Note that sunrpc code *does* call hash_mem() with a zero length, which
is why the previous patch needed to handle that in full_name_hash().
(Thanks, Bruce, for finding that!)
This also eliminates the only caller of hash_long which asks for
more than 32 bits of output.
The comment about the quality of hashlen_string() and full_name_hash()
is jumping the gun by a few patches; they aren't very impressive now,
but will be improved greatly later in the series.
Signed-off-by: George Spelvin <[email protected]>
Tested-by: J. Bruce Fields <[email protected]>
Acked-by: J. Bruce Fields <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: [email protected]
|
|
We'd like to make more use of the highly-optimized dcache hash functions
throughout the kernel, rather than have every subsystem create its own,
and a function that hashes basic null-terminated strings is required
for that.
(The name is to emphasize that it returns both hash and length.)
It's actually useful in the dcache itself, specifically d_alloc_name().
Other uses in the next patch.
full_name_hash() is also tweaked to make it more generally useful:
1) Take a "char *" rather than "unsigned char *" argument, to
be consistent with hash_name().
2) Handle zero-length inputs. If we want more callers, we don't want
to make them worry about corner cases.
Signed-off-by: George Spelvin <[email protected]>
|