Commit 8fd5e7a2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'metag-v3.9-rc1-v4' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag 

Pull new ImgTec Meta architecture from James Hogan:
 "This adds core architecture support for Imagination's Meta processor
  cores, followed by some later miscellaneous arch/metag cleanups and
  fixes which I kept separate to ease review:

   - Support for basic Meta 1 (ATP) and Meta 2 (HTP) core architecture
   - A few fixes all over, particularly for symbol prefixes
   - A few privilege protection fixes
   - Several cleanups (setup.c includes, split out a lot of
     metag_ksyms.c)
   - Fix some missing exports
   - Convert hugetlb to use vm_unmapped_area()
   - Copy device tree to non-init memory
   - Provide dma_get_sgtable()"

* tag 'metag-v3.9-rc1-v4' of git://git.kernel.org/pub/scm/linux/kernel/git/jhogan/metag: (61 commits)
  metag: Provide dma_get_sgtable()
  metag: prom.h: remove declaration of metag_dt_memblock_reserve()
  metag: copy devicetree to non-init memory
  metag: cleanup metag_ksyms.c includes
  metag: move mm/init.c exports out of metag_ksyms.c
  metag: move usercopy.c exports out of metag_ksyms.c
  metag: move setup.c exports out of metag_ksyms.c
  metag: move kick.c exports out of metag_ksyms.c
  metag: move traps.c exports out of metag_ksyms.c
  metag: move irq enable out of irqflags.h on SMP
  genksyms: fix metag symbol prefix on crc symbols
  metag: hugetlb: convert to vm_unmapped_area()
  metag: export clear_page and copy_page
  metag: export metag_code_cache_flush_all
  metag: protect more non-MMU memory regions
  metag: make TXPRIVEXT bits explicit
  metag: kernel/setup.c: sort includes
  perf: Enable building perf tools for Meta
  metag: add boot time LNKGET/LNKSET check
  metag: add __init to metag_cache_probe()
  ...
parents 529e5fbc c60ac315

Documentation/00-INDEX

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@@ -299,6 +299,8 @@ memory-hotplug.txt 
	- Hotpluggable memory support, how to use and current status.

memory.txt

	- info on typical Linux memory problems.

metag/

	- directory with info about Linux on Meta architecture.

mips/

	- directory with info about Linux on MIPS architecture.

misc-devices/

Documentation/devicetree/bindings/metag/meta-intc.txt

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* Meta External Trigger Controller Binding



This binding specifies what properties must be available in the device tree

representation of a Meta external trigger controller.



Required properties:



    - compatible: Specifies the compatibility list for the interrupt controller.

      The type shall be <string> and the value shall include "img,meta-intc".



    - num-banks: Specifies the number of interrupt banks (each of which can

      handle 32 interrupt sources).



    - interrupt-controller: The presence of this property identifies the node

      as an interupt controller. No property value shall be defined.



    - #interrupt-cells: Specifies the number of cells needed to encode an

      interrupt source. The type shall be a <u32> and the value shall be 2.



    - #address-cells: Specifies the number of cells needed to encode an

      address. The type shall be <u32> and the value shall be 0. As such,

      'interrupt-map' nodes do not have to specify a parent unit address.



Optional properties:



    - no-mask: The controller doesn't have any mask registers.



* Interrupt Specifier Definition



  Interrupt specifiers consists of 2 cells encoded as follows:



    - <1st-cell>: The interrupt-number that identifies the interrupt source.



    - <2nd-cell>: The Linux interrupt flags containing level-sense information,

                  encoded as follows:

                    1 = edge triggered

                    4 = level-sensitive



* Examples



Example 1:



	/*

	 * Meta external trigger block

	 */

	intc: intc {

		// This is an interrupt controller node.

		interrupt-controller;



		// No address cells so that 'interrupt-map' nodes which

		// reference this interrupt controller node do not need a parent

		// address specifier.

		#address-cells = <0>;



		// Two cells to encode interrupt sources.

		#interrupt-cells = <2>;



		// Number of interrupt banks

		num-banks = <2>;



		// No HWMASKEXT is available (specify on Chorus2 and Comet ES1)

		no-mask;



		// Compatible with Meta hardware trigger block.

		compatible = "img,meta-intc";

	};



Example 2:



	/*

	 * An interrupt generating device that is wired to a Meta external

	 * trigger block.

	 */

	uart1: uart@0x02004c00 {

		// Interrupt source '5' that is level-sensitive.

		// Note that there are only two cells as specified in the

		// interrupt parent's '#interrupt-cells' property.

		interrupts = <5 4 /* level */>;



		// The interrupt controller that this device is wired to.

		interrupt-parent = <&intc>;

	};

Documentation/kernel-parameters.txt

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@@ -978,6 +978,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
			       If specified, z/VM IUCV HVC accepts connections

			       from listed z/VM user IDs only.



	hwthread_map=	[METAG] Comma-separated list of Linux cpu id to

			        hardware thread id mappings.

				Format: <cpu>:<hwthread>



	keep_bootcon	[KNL]

			Do not unregister boot console at start. This is only

			useful for debugging when something happens in the window

Documentation/metag/00-INDEX

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00-INDEX

	- this file

kernel-ABI.txt

	- Documents metag ABI details

Documentation/metag/kernel-ABI.txt

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			==========================

			KERNEL ABIS FOR METAG ARCH

			==========================



This document describes the Linux ABIs for the metag architecture, and has the

following sections:



 (*) Outline of registers

 (*) Userland registers

 (*) Kernel registers

 (*) System call ABI

 (*) Calling conventions





====================

OUTLINE OF REGISTERS

====================



The main Meta core registers are arranged in units:



	UNIT	Type	DESCRIPTION	GP	EXT	PRIV	GLOBAL

	=======	=======	===============	=======	=======	=======	=======

	CT	Special	Control unit

	D0	General	Data unit 0	0-7	8-15	16-31	16-31

	D1	General	Data unit 1	0-7	8-15	16-31	16-31

	A0	General	Address unit 0	0-3	4-7	 8-15	 8-15

	A1	General	Address unit 1	0-3	4-7	 8-15	 8-15

	PC	Special	PC unit		0		 1

	PORT	Special	Ports

	TR	Special	Trigger unit			 0-7

	TT	Special	Trace unit			 0-5

	FX	General	FP unit			0-15



GP registers form part of the main context.



Extended context registers (EXT) may not be present on all hardware threads and

can be context switched if support is enabled and the appropriate bits are set

in e.g. the D0.8 register to indicate what extended state to preserve.



Global registers are shared between threads and are privilege protected.



See arch/metag/include/asm/metag_regs.h for definitions relating to core

registers and the fields and bits they contain. See the TRMs for further details

about special registers.



Several special registers are preserved in the main context, these are the

interesting ones:



	REG	(ALIAS)		PURPOSE

	=======================	===============================================

	CT.1	(TXMODE)	Processor mode bits (particularly for DSP)

	CT.2	(TXSTATUS)	Condition flags and LSM_STEP (MGET/MSET step)

	CT.3	(TXRPT)		Branch repeat counter

	PC.0	(PC)		Program counter



Some of the general registers have special purposes in the ABI and therefore

have aliases:



	D0 REG	(ALIAS)	PURPOSE		D1 REG	(ALIAS)	PURPOSE

	===============	===============	===============	=======================

	D0.0	(D0Re0)	32bit result	D1.0	(D1Re0)	Top half of 64bit result

	D0.1	(D0Ar6)	Argument 6	D1.1	(D1Ar5)	Argument 5

	D0.2	(D0Ar4)	Argument 4	D1.2	(D1Ar3)	Argument 3

	D0.3	(D0Ar2)	Argument 2	D1.3	(D1Ar1)	Argument 1

	D0.4	(D0FrT)	Frame temp	D1.4	(D1RtP)	Return pointer

	D0.5		Call preserved	D1.5		Call preserved

	D0.6		Call preserved	D1.6		Call preserved

	D0.7		Call preserved	D1.7		Call preserved



	A0 REG	(ALIAS)	PURPOSE		A1 REG	(ALIAS)	PURPOSE

	===============	===============	===============	=======================

	A0.0	(A0StP)	Stack pointer	A1.0	(A1GbP)	Global base pointer

	A0.1	(A0FrP)	Frame pointer	A1.1	(A1LbP)	Local base pointer

	A0.2				A1.2

	A0.3				A1.3





==================

USERLAND REGISTERS

==================



All the general purpose D0, D1, A0, A1 registers are preserved when entering the

kernel (including asynchronous events such as interrupts and timer ticks) except

the following which have special purposes in the ABI:



	REGISTERS	WHEN	STATUS		PURPOSE

	===============	=======	===============	===============================

	D0.8		DSP	Preserved	ECH, determines what extended

						DSP state to preserve.

	A0.0	(A0StP)	ALWAYS	Preserved	Stack >= A0StP may be clobbered

						at any time by the creation of a

						signal frame.

	A1.0	(A1GbP)	SMP	Clobbered	Used as temporary for loading

						kernel stack pointer and saving

						core context.

	A0.15		!SMP	Protected	Stores kernel stack pointer.

	A1.15		ALWAYS	Protected	Stores kernel base pointer.



On UP A0.15 is used to store the kernel stack pointer for storing the userland

context. A0.15 is global between hardware threads though which means it cannot

be used on SMP for this purpose. Since no protected local registers are

available A1GbP is reserved for use as a temporary to allow a percpu stack

pointer to be loaded for storing the rest of the context.





================

KERNEL REGISTERS

================



When in the kernel the following registers have special purposes in the ABI:



	REGISTERS	WHEN	STATUS		PURPOSE

	===============	=======	===============	===============================

	A0.0	(A0StP)	ALWAYS	Preserved	Stack >= A0StP may be clobbered

						at any time by the creation of

						an irq signal frame.

	A1.0	(A1GbP)	ALWAYS	Preserved	Reserved (kernel base pointer).





===============

SYSTEM CALL ABI

===============



When a system call is made, the following registers are effective:



	REGISTERS	CALL			RETURN

	===============	=======================	===============================

	D0.0	(D0Re0)				Return value (or -errno)

	D1.0	(D1Re0)	System call number	Clobbered

	D0.1	(D0Ar6)	Syscall arg #6		Preserved

	D1.1	(D1Ar5)	Syscall arg #5		Preserved

	D0.2	(D0Ar4)	Syscall arg #4		Preserved

	D1.2	(D1Ar3)	Syscall arg #3		Preserved

	D0.3	(D0Ar2)	Syscall arg #2		Preserved

	D1.3	(D1Ar1)	Syscall arg #1		Preserved



Due to the limited number of argument registers and some system calls with badly

aligned 64-bit arguments, 64-bit values are always packed in consecutive

arguments, even if this is contrary to the normal calling conventions (where the

two halves would go in a matching pair of data registers).



For example fadvise64_64 usually has the signature:



	long sys_fadvise64_64(i32 fd, i64 offs, i64 len, i32 advice);



But for metag fadvise64_64 is wrapped so that the 64-bit arguments are packed:



	long sys_fadvise64_64_metag(i32 fd,      i32 offs_lo,

				    i32 offs_hi, i32 len_lo,

				    i32 len_hi,  i32 advice)



So the arguments are packed in the registers like this:



	D0 REG	(ALIAS)	VALUE		D1 REG	(ALIAS)	VALUE

	===============	===============	===============	=======================

	D0.1	(D0Ar6)	advice		D1.1	(D1Ar5)	hi(len)

	D0.2	(D0Ar4)	lo(len)		D1.2	(D1Ar3)	hi(offs)

	D0.3	(D0Ar2)	lo(offs)	D1.3	(D1Ar1)	fd





===================

CALLING CONVENTIONS

===================



These calling conventions apply to both user and kernel code. The stack grows

from low addresses to high addresses in the metag ABI. The stack pointer (A0StP)

should always point to the next free address on the stack and should at all

times be 64-bit aligned. The following registers are effective at the point of a

call:



	REGISTERS	CALL			RETURN

	===============	=======================	===============================

	D0.0	(D0Re0)				32bit return value

	D1.0	(D1Re0)				Upper half of 64bit return value

	D0.1	(D0Ar6)	32bit argument #6	Clobbered

	D1.1	(D1Ar5)	32bit argument #5	Clobbered

	D0.2	(D0Ar4)	32bit argument #4	Clobbered

	D1.2	(D1Ar3)	32bit argument #3	Clobbered

	D0.3	(D0Ar2)	32bit argument #2	Clobbered

	D1.3	(D1Ar1)	32bit argument #1	Clobbered

	D0.4	(D0FrT)				Clobbered

	D1.4	(D1RtP)	Return pointer		Clobbered

	D{0-1}.{5-7}				Preserved

	A0.0	(A0StP)	Stack pointer		Preserved

	A1.0	(A0GbP)				Preserved

	A0.1	(A0FrP)	Frame pointer		Preserved

	A1.1	(A0LbP)				Preserved

	A{0-1},{2-3}				Clobbered



64-bit arguments are placed in matching pairs of registers (i.e. the same

register number in both D0 and D1 units), with the least significant half in D0

and the most significant half in D1, leaving a gap where necessary. Futher

arguments are stored on the stack in reverse order (earlier arguments at higher

addresses):



	ADDRESS		0     1     2     3	4     5     6     7

	===============	===== ===== ===== =====	===== ===== ===== =====

	A0StP       -->

	A0StP-0x08	32bit argument #8	32bit argument #7

	A0StP-0x10	32bit argument #10	32bit argument #9



Function prologues tend to look a bit like this:



	/* If frame pointer in use, move it to frame temp register so it can be

	   easily pushed onto stack */

	MOV	D0FrT,A0FrP



	/* If frame pointer in use, set it to stack pointer */

	ADD	A0FrP,A0StP,#0



	/* Preserve D0FrT, D1RtP, D{0-1}.{5-7} on stack, incrementing A0StP */

	MSETL	[A0StP++],D0FrT,D0.5,D0.6,D0.7



	/* Allocate some stack space for local variables */

	ADD	A0StP,A0StP,#0x10



At this point the stack would look like this:



	ADDRESS		0     1     2     3	4     5     6     7

	===============	===== ===== ===== =====	===== ===== ===== =====

	A0StP       -->

	A0StP-0x08

	A0StP-0x10

	A0StP-0x18	Old D0.7		Old D1.7

	A0StP-0x20	Old D0.6		Old D1.6

	A0StP-0x28	Old D0.5		Old D1.5

	A0FrP       -->	Old A0FrP (frame ptr)	Old D1RtP (return ptr)

	A0FrP-0x08	32bit argument #8	32bit argument #7

	A0FrP-0x10	32bit argument #10	32bit argument #9



Function epilogues tend to differ depending on the use of a frame pointer. An

example of a frame pointer epilogue:



	/* Restore D0FrT, D1RtP, D{0-1}.{5-7} from stack, incrementing A0FrP */

	MGETL	D0FrT,D0.5,D0.6,D0.7,[A0FrP++]

	/* Restore stack pointer to where frame pointer was before increment */

	SUB	A0StP,A0FrP,#0x20

	/* Restore frame pointer from frame temp */

	MOV	A0FrP,D0FrT

	/* Return to caller via restored return pointer */

	MOV	PC,D1RtP



If the function hasn't touched the frame pointer, MGETL cannot be safely used

with A0StP as it always increments and that would expose the stack to clobbering

by interrupts (kernel) or signals (user). Therefore it's common to see the MGETL

split into separate GETL instructions:



	/* Restore D0FrT, D1RtP, D{0-1}.{5-7} from stack */

	GETL	D0FrT,D1RtP,[A0StP+#-0x30]

	GETL	D0.5,D1.5,[A0StP+#-0x28]

	GETL	D0.6,D1.6,[A0StP+#-0x20]

	GETL	D0.7,D1.7,[A0StP+#-0x18]

	/* Restore stack pointer */

	SUB	A0StP,A0StP,#0x30

	/* Return to caller via restored return pointer */

	MOV	PC,D1RtP

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