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source: trunk/hal/tsar_mips32/hal_gpt.c @ 26

Last change on this file since 26 was 23, checked in by alain, 8 years ago
Introduce syscalls.
File size: 23.0 KB

Rev	Line
[1]	1	/*
	2	* hal_gpt.c - implementation of the Generic Page Table API for TSAR-MIPS32
	3	*
	4	* Author Alain Greiner (2016)
	5	*
	6	* Copyright (c) UPMC Sorbonne Universites
	7	*
	8	* This file is part of ALMOS-MKH.
	9	*
	10	* ALMOS-MKH.is free software; you can redistribute it and/or modify it
	11	* under the terms of the GNU General Public License as published by
	12	* the Free Software Foundation; version 2.0 of the License.
	13	*
	14	* ALMOS-MKH.is distributed in the hope that it will be useful, but
	15	* WITHOUT ANY WARRANTY; without even the implied warranty of
	16	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	17	* General Public License for more details.
	18	*
	19	* You should have received a copy of the GNU General Public License
	20	* along with ALMOS-MKH.; if not, write to the Free Software Foundation,
	21	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	22	*/
	23
	24	#include <hal_types.h>
	25	#include <hal_gpt.h>
	26	#include <hal_special.h>
	27	#include <printk.h>
	28	#include <bits.h>
	29	#include <process.h>
	30	#include <kmem.h>
	31	#include <thread.h>
	32	#include <cluster.h>
	33	#include <ppm.h>
	34	#include <page.h>
	35
	36	////////////////////////////////////////////////////////////////////////////////////////
	37	// This define the masks for the TSAR MMU PTE attributes. (from TSAR MMU specification)
	38	// the GPT masks are derived from the TSAR MMU PTE attributes
	39	// in the TSAR specific hal_gpt_create() function.
	40	////////////////////////////////////////////////////////////////////////////////////////
	41
	42	#define TSAR_MMU_PRESENT 0x80000000
	43	#define TSAR_MMU_PTD1 0x40000000
	44	#define TSAR_MMU_LOCAL 0x20000000
	45	#define TSAR_MMU_REMOTE 0x10000000
	46	#define TSAR_MMU_CACHABLE 0x08000000
	47	#define TSAR_MMU_WRITABLE 0x04000000
	48	#define TSAR_MMU_EXECUTABLE 0x02000000
	49	#define TSAR_MMU_USER 0x01000000
	50	#define TSAR_MMU_GLOBAL 0x00800000
	51	#define TSAR_MMU_DIRTY 0x00400000
	52
	53	#define TSAR_MMU_COW 0x00000001
	54	#define TSAR_MMU_SWAP 0x00000004
	55	#define TSAR_MMU_LOCKED 0x00000008
	56
	57	////////////////////////////////////////////////////////////////////////////////////////
	58	// TSAR MMU related macros (from the TSAR MMU specification)
	59	// - IX1 on 11 bits
	60	// - IX2 on 9 bits
	61	// - PPN on 28 bits
	62	////////////////////////////////////////////////////////////////////////////////////////
	63
	64	#define TSAR_MMU_IX1_WIDTH 11
	65	#define TSAR_MMU_IX2_WIDTH 9
	66	#define TSAR_MMU_PPN_WIDTH 28
	67
	68	#define TSAR_MMU_IX1_FROM_VPN( vpn ) ((vpn >> 9) & 0x7FF)
	69	#define TSAR_MMU_IX2_FROM_VPN( vpn ) (vpn & 0x1FF)
	70
	71	#define TSAR_MMU_PTBA_FROM_PTE1( pte1 ) (pte1 & 0xFFFFFFF)
	72	#define TSAR_MMU_PPN_FROM_PTE1( pte1 ) ((pte1 & 0x7FFFF)<<9)
	73	#define TSAR_MMU_ATTR_FROM_PTE1( pte1 ) (pte1 & 0xFFC00000)
	74
	75	#define TSAR_MMU_PPN_FROM_PTE2( pte2 ) (pte2 & 0x0FFFFFFF)
	76	#define TSAR_MMU_ATTR_FROM_PTE2( pte2 ) (pte2 & 0xFFC000FF)
	77
	78	/****************************************************************************************
	79	* These global variables defines the masks for the Generic Page Table Entry attributes,
	80	* and must be defined in all GPT implementation.
	81	***************************************************************************************/
	82
	83	uint32_t GPT_MAPPED;
	84	uint32_t GPT_SMALL;
	85	uint32_t GPT_READABLE;
	86	uint32_t GPT_WRITABLE;
	87	uint32_t GPT_EXECUTABLE;
	88	uint32_t GPT_CACHABLE;
	89	uint32_t GPT_USER;
	90	uint32_t GPT_DIRTY;
	91	uint32_t GPT_ACCESSED;
	92	uint32_t GPT_GLOBAL;
	93	uint32_t GPT_COW;
	94	uint32_t GPT_SWAP;
	95	uint32_t GPT_LOCKED;
	96
	97	/////////////////////////////////////
	98	error_t hal_gpt_create( gpt_t * gpt )
	99	{
	100	page_t * page;
	101
	102	// check page size
	103	if( CONFIG_PPM_PAGE_SIZE != 4096 );
	104	{
	105	printk("\n[PANIC] in %s : For TSAR, the page must be 4 Kbytes\n", __FUNCTION__ );
	106	hal_core_sleep();
	107	}
	108
	109	// allocates 2 physical pages for PT1
	110	kmem_req_t req;
	111	req.type = KMEM_PAGE;
	112	req.size = 1; // 2 small pages
	113	req.flags = AF_KERNEL \| AF_ZERO;
	114	page = (page_t *)kmem_alloc( &req );
	115
	116	if( page == NULL )
	117	{
	118	printk("\n[ERROR] in %s : cannot allocate physical memory for PT1\n", __FUNCTION__ );
	119	return ENOMEM;
	120	}
	121
	122	// initialize generic page table descriptor
	123	gpt->ptr = ppm_page2base( page );
	124	gpt->ppn = ppm_page2ppn( page );
	125	gpt->page = page;
	126
	127	// initialize PTE entries attributes masks
	128	GPT_MAPPED = TSAR_MMU_PRESENT;
	129	GPT_SMALL = TSAR_MMU_PTD1;
	130	GPT_READABLE = TSAR_MMU_PRESENT;
	131	GPT_WRITABLE = TSAR_MMU_WRITABLE;
	132	GPT_EXECUTABLE = TSAR_MMU_EXECUTABLE;
	133	GPT_CACHABLE = TSAR_MMU_CACHABLE;
	134	GPT_USER = TSAR_MMU_USER;
	135	GPT_DIRTY = TSAR_MMU_DIRTY;
	136	GPT_ACCESSED = TSAR_MMU_LOCAL \| TSAR_MMU_REMOTE;
	137	GPT_GLOBAL = TSAR_MMU_GLOBAL;
	138	GPT_COW = TSAR_MMU_COW;
	139	GPT_SWAP = TSAR_MMU_SWAP;
	140	GPT_LOCKED = TSAR_MMU_LOCKED;
	141
	142	return 0;
	143	} // end hal_gpt_create()
	144
	145
	146	///////////////////////////////////
	147	void hal_gpt_destroy( gpt_t * gpt )
	148	{
	149	uint32_t ix1;
	150	uint32_t ix2;
	151	uint32_t * pt1;
	152	uint32_t pte1;
	153	ppn_t pt2_ppn;
	154	uint32_t * pt2;
	155	uint32_t attr;
	156	vpn_t vpn;
	157	kmem_req_t req;
	158	bool_t is_ref;
	159
	160	// get pointer on calling process
	161	process_t * process = CURRENT_THREAD->process;
	162
	163	// compute is_ref
[23]	164	is_ref = ( GET_CXY( process->ref_xp ) == local_cxy );
[1]	165
	166	// get pointer on PT1
	167	pt1 = (uint32_t *)gpt->ptr;
	168
	169	// scan the PT1
	170	for( ix1 = 0 ; ix1 < 2048 ; ix1++ )
	171	{
	172	pte1 = pt1[ix1];
	173	if( (pte1 & GPT_MAPPED) != 0 ) // PTE1 valid
	174	{
	175	if( (pte1 & GPT_SMALL) == 0 ) // BIG page
	176	{
	177	if( (pte1 & GPT_USER) != 0 )
	178	{
	179	// warning message
	180	printk("\n[WARNING] in %s : found an USER BIG page / ix1 = %d\n",
	181	__FUNCTION__ , ix1 );
	182
	183	// release the big physical page if reference cluster
	184	if( is_ref )
	185	{
	186	vpn = (vpn_t)(ix1 << TSAR_MMU_IX2_WIDTH);
	187	hal_gpt_reset_pte( gpt , vpn );
	188	}
	189	}
	190	}
	191	else // SMALL page
	192	{
	193	// get pointer on PT2
	194	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	195	pt2 = ppm_ppn2base( pt2_ppn );
	196
	197	// scan the PT2 to release all entries VALID and USER if reference cluster
	198	if( is_ref )
	199	{
	200	for( ix2 = 0 ; ix2 < 512 ; ix2++ )
	201	{
	202	attr = TSAR_MMU_ATTR_FROM_PTE2( pt2[2 * ix2] );
	203	if( ((attr & GPT_MAPPED) != 0 ) && ((attr & GPT_USER) != 0) )
	204	{
	205	// release the physical page
	206	vpn = (vpn_t)((ix1 << TSAR_MMU_IX2_WIDTH) \| ix2);
	207	hal_gpt_reset_pte( gpt , vpn );
	208	}
	209	}
	210	}
	211
	212	// release the PT2
	213	req.type = KMEM_PAGE;
	214	req.ptr = ppm_base2page( pt2 );
	215	kmem_free( &req );
	216	}
	217	}
	218	}
	219
	220	// release the PT1
	221	req.type = KMEM_PAGE;
	222	req.ptr = ppm_base2page( pt1 );
	223	kmem_free( &req );
	224
	225	} // end hal_gpt_destroy()
	226
	227	/////////////////////////////////
	228	void hal_gpt_print( gpt_t * gpt )
	229	{
	230	uint32_t ix1;
	231	uint32_t ix2;
	232	uint32_t * pt1;
	233	uint32_t pte1;
	234	ppn_t pt2_ppn;
	235	uint32_t * pt2;
	236	uint32_t pte2_attr;
	237	ppn_t pte2_ppn;
	238
	239	printk("* Page Table for process %x in cluster %x *\n",
[23]	240	CURRENT_THREAD->process->pid , local_cxy );
[1]	241
	242	pt1 = (uint32_t *)gpt->ptr;
	243
	244	// scan the PT1
	245	for( ix1 = 0 ; ix1 < 2048 ; ix1++ )
	246	{
	247	pte1 = pt1[ix1];
	248	if( (pte1 & GPT_MAPPED) != 0 )
	249	{
	250	if( (pte1 & GPT_SMALL) == 0 ) // BIG page
	251	{
	252	printk(" - BIG : pt1[%d] = %x\n", ix1 , pte1 );
	253	}
	254	else // SMALL pages
	255	{
	256	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	257	pt2 = ppm_ppn2base( pt2_ppn );
	258
	259	// scan the PT2
	260	for( ix2 = 0 ; ix2 < 512 ; ix2++ )
	261	{
	262	pte2_attr = TSAR_MMU_ATTR_FROM_PTE2( pt2[2 * ix2] );
	263	pte2_ppn = TSAR_MMU_PPN_FROM_PTE2( pt2[2 * ix2 + 1] );
	264	if( (pte2_attr & GPT_MAPPED) != 0 )
	265	{
	266	printk(" - SMALL : pt1[%d] = %x / pt2[%d] / pt2[%d]\n",
	267	ix1 , pt1[ix1] , 2ix2 , pte2_attr , 2ix2+1 , pte2_ppn );
	268	}
	269	}
	270	}
	271	}
	272	}
	273	} // end hal_gpt_print()
	274
	275
	276	///////////////////////////////////////
	277	error_t hal_gpt_set_pte( gpt_t * gpt,
	278	vpn_t vpn,
	279	ppn_t ppn,
	280	uint32_t attr )
	281	{
	282	uint32_t * pt1; // virtual base addres of PT1
	283	volatile uint32_t * pte1_ptr; // pointer on PT1 entry
	284	uint32_t pte1; // PT1 entry value
	285
	286	ppn_t pt2_ppn; // PPN of PT2
	287	uint32_t * pt2; // virtual base address of PT2
	288
	289	uint32_t small; // requested PTE is for a small page
	290	bool_t atomic; //
	291	page_t * page; // pointer on new physical page descriptor
	292
	293	uint32_t ix1; // index in PT1
	294	uint32_t ix2; // index in PT2
	295
	296	// compute indexes in PT1 and PT2
	297	ix1 = TSAR_MMU_IX1_FROM_VPN( vpn );
	298	ix2 = TSAR_MMU_IX2_FROM_VPN( vpn );
	299
	300	pt1 = gpt->ptr;
	301	small = (attr & GPT_SMALL);
	302
	303	// get PT1 entry value
	304	pte1_ptr = &pt1[ix1];
	305	pte1 = *pte1_ptr;
	306
	307	// Big pages (PTE1) are only set for the kernel vsegs, in the kernel init phase.
	308	// There is no risk of concurrent access.
	309	if( small == 0 )
	310	{
	311	if( (pte1 != 0) \|\| (attr & GPT_COW) )
	312	{
	313	printk("\n[ERROR] in %s : set a big page in a mapped PT1 entry / PT1[%d] = %x\n",
	314	__FUNCTION__ , ix1 , pte1 );
	315	return EINVAL;
	316	}
	317
	318	// set the PTE1
	319	*pte1_ptr = attr \| (ppn >> 9);
	320	hal_wbflush();
	321	return 0;
	322	}
	323
	324	// From this point, the requested PTE is a PTE2 (small page)
	325
	326	if( (pte1 & GPT_MAPPED) == 0 ) // the PT1 entry is not valid
	327	{
	328	// allocate one physical page for the PT2
	329	kmem_req_t req;
	330	req.type = KMEM_PAGE;
	331	req.size = 0; // 1 small page
	332	req.flags = AF_KERNEL \| AF_ZERO;
	333	page = (page_t *)kmem_alloc( &req );
	334	if( page == NULL )
	335	{
	336	printk("\n[ERROR] in %s : try to set a small page but cannot allocate PT2\n",
	337	__FUNCTION__ );
	338	return ENOMEM;
	339	}
	340	pt2_ppn = ppm_page2ppn( page );
	341	pt2 = ppm_page2base( page );
	342
	343	// try to atomicaly set a PTD1 in the PT1 entry
	344	do
	345	{
	346	atomic = hal_atomic_cas( (void*)pte1, 0 ,
	347	TSAR_MMU_PRESENT \| TSAR_MMU_PTD1 \| pt2_ppn );
	348	}
	349	while( (atomic == false) && (*pte1_ptr == 0) );
	350
	351	if( atomic == false ) // the mapping has been done by another thread !!!
	352	{
	353	// release the allocated page
	354	ppm_free_pages( page );
	355
	356	// read PT1 entry again
	357	pte1 = *pte1_ptr;
	358
	359	// compute PPN of PT2 base
	360	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	361
	362	// compute pointer on PT2 base
	363	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	364	}
	365	}
	366	else // The PT1 entry is valid
	367	{
	368	// This valid entry must be a PTD1
	369	if( (pte1 & GPT_SMALL) == 0 )
	370	{
	371	printk("\n[ERROR] in %s : set a small page in a big PT1 entry / PT1[%d] = %x\n",
	372	__FUNCTION__ , ix1 , pte1 );
	373	return EINVAL;
	374	}
	375
	376	// compute PPN of PT2 base
	377	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	378
	379	// compute pointer on PT2 base
	380	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	381	}
	382
	383	// set PTE2 in this order
	384	pt2[2 * ix2 + 1] = ppn;
	385	hal_wbflush();
	386	pt2[2 * ix2] = attr;
	387	hal_wbflush();
	388
	389	return 0;
	390	} // end of hal_gpt_set_pte()
	391
	392	/////////////////////////////////////
	393	void hal_gpt_get_pte( gpt_t * gpt,
	394	vpn_t vpn,
	395	uint32_t * attr,
	396	ppn_t * ppn )
	397	{
	398	uint32_t * pt1;
	399	uint32_t pte1;
	400
	401	uint32_t * pt2;
	402	ppn_t pt2_ppn;
	403
	404	uint32_t ix1 = TSAR_MMU_IX1_FROM_VPN( vpn );
	405	uint32_t ix2 = TSAR_MMU_IX2_FROM_VPN( vpn );
	406
	407	// get PTE1 value
	408	pt1 = gpt->ptr;
	409	pte1 = pt1[ix1];
	410
	411	if( (pte1 & GPT_MAPPED) == 0 ) // PT1 entry not present
	412	{
	413	*attr = 0;
	414	*ppn = 0;
	415	}
	416
	417	if( (pte1 & GPT_SMALL) == 0 ) // it's a PTE1
	418	{
	419	*attr = TSAR_MMU_ATTR_FROM_PTE1( pte1 );
	420	*ppn = TSAR_MMU_PPN_FROM_PTE1( pte1 ) \| (vpn & ((1<<TSAR_MMU_IX2_WIDTH)-1));
	421	}
	422	else // it's a PTD1
	423	{
	424	// compute PT2 base address
	425	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	426	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	427
	428	ppn = pt2[2ix2+1] & ((1<<TSAR_MMU_PPN_WIDTH)-1);
	429	attr = pt2[2ix2];
	430	}
	431	} // end hal_gpt_get_pte()
	432
	433	////////////////////////////////////
	434	void hal_gpt_reset_pte( gpt_t * gpt,
	435	vpn_t vpn )
	436	{
	437	uint32_t * pt1; // PT1 base address
	438	uint32_t pte1; // PT1 entry value
	439
	440	ppn_t pt2_ppn; // PPN of PT2
	441	uint32_t * pt2; // PT2 base address
	442
	443	ppn_t ppn; // PPN of page to be released
	444
	445	kmem_req_t req;
	446
	447	uint32_t ix1 = TSAR_MMU_IX1_FROM_VPN( vpn );
	448	uint32_t ix2 = TSAR_MMU_IX2_FROM_VPN( vpn );
	449
	450	// get PTE1 value
	451	pt1 = gpt->ptr;
	452	pte1 = pt1[ix1];
	453
	454	if( (pte1 & GPT_MAPPED) == 0 ) // PT1 entry not present
	455	{
	456	return;
	457	}
	458
	459	if( (pte1 & GPT_SMALL) == 0 ) // it's a PTE1
	460	{
	461	// get PPN
	462	ppn = TSAR_MMU_PPN_FROM_PTE1( pte1 );
	463
	464	// unmap the big page
	465	pt1[ix1] = 0;
	466	hal_wbflush();
	467
	468	// releases the big page
	469	req.type = KMEM_PAGE;
	470	req.size = 9;
	471	req.ptr = (void*)(ppn << CONFIG_PPM_PAGE_SHIFT);
	472	kmem_free( &req );
	473
	474	return;
	475	}
	476	else // it's a PTD1
	477	{
	478	// compute PT2 base address
	479	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	480	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	481
	482	// get PPN
	483	ppn = TSAR_MMU_PPN_FROM_PTE2( pt2[2*ix2+1] );
	484
	485	// unmap the small page
	486	pt2[2*ix2] = 0;
	487	hal_wbflush();
	488	pt2[2*ix2+1] = 0;
	489	hal_wbflush();
	490
	491	// releases the small page
	492	req.type = KMEM_PAGE;
	493	req.size = 0;
	494	req.ptr = (void*)(ppn << CONFIG_PPM_PAGE_SHIFT);
	495	kmem_free( &req );
	496
	497	return;
	498	}
	499	} // end hal_gpt_reset_pte()
	500
	501	//////////////////////////////////////
	502	error_t hal_gpt_lock_pte( gpt_t * gpt,
	503	vpn_t vpn )
	504	{
	505	uint32_t * pt1; // PT1 base address
	506	volatile uint32_t * pte1_ptr; // address of PT1 entry
	507	uint32_t pte1; // value of PT1 entry
	508
	509	uint32_t * pt2; // PT2 base address
	510	ppn_t pt2_ppn; // PPN of PT2 page if missing PT2
	511	volatile uint32_t * pte2_ptr; // address of PT2 entry
	512
	513	uint32_t attr;
	514	bool_t atomic;
	515	page_t * page;
	516
	517	uint32_t ix1 = TSAR_MMU_IX1_FROM_VPN( vpn ); // index in PT1
	518	uint32_t ix2 = TSAR_MMU_IX2_FROM_VPN( vpn ); // index in PT2
	519
	520	// get the PTE1 value
	521	pt1 = gpt->ptr;
	522	pte1_ptr = &pt1[ix1];
	523	pte1 = *pte1_ptr;
	524
	525	// If present, the page must be small
	526	if( ((pte1 & GPT_MAPPED) != 0) && ((pte1 & GPT_SMALL) == 0) )
	527	{
	528	printk("\n[ERROR] in %s : try to lock a big page / PT1[%d] = %x\n",
	529	__FUNCTION__ , ix1 , pte1 );
	530	return EINVAL;
	531	}
	532
	533	if( (pte1 & GPT_MAPPED) == 0 ) // missing PT1 entry
	534	{
	535	// allocate one physical page for PT2
	536	kmem_req_t req;
	537	req.type = KMEM_PAGE;
	538	req.size = 0; // 1 small page
	539	req.flags = AF_KERNEL \| AF_ZERO;
	540	page = (page_t *)kmem_alloc( &req );
[23]	541
[1]	542	if( page == NULL )
	543	{
	544	printk("\n[ERROR] in %s : try to set a small page but cannot allocate PT2\n",
	545	__FUNCTION__ );
	546	return ENOMEM;
	547	}
[23]	548
[1]	549	pt2_ppn = ppm_page2ppn( page );
	550	pt2 = ppm_page2base( page );
	551
	552	// try to set the PT1 entry
	553	do
	554	{
	555	atomic = hal_atomic_cas( (void*)pte1_ptr , 0 ,
	556	TSAR_MMU_PRESENT \| TSAR_MMU_PTD1 \| pt2_ppn );
	557	}
	558	while( (atomic == false) && (*pte1_ptr == 0) );
	559
	560	if( atomic == false ) // missing PT2 has been allocate by another core
	561	{
	562	// release the allocated page
	563	ppm_free_pages( page );
	564
	565	// read again the PTE1
	566	pte1 = *pte1_ptr;
	567
	568	// get the PT2 base address
	569	pt2_ppn = TSAR_MMU_PPN_FROM_PTE1( pte1 );
	570	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	571	}
	572	}
	573	else
	574	{
	575	// This valid entry must be a PTD1
	576	if( (pte1 & GPT_SMALL) == 0 )
	577	{
	578	printk("\n[ERROR] in %s : set a small page in a big PT1 entry / PT1[%d] = %x\n",
	579	__FUNCTION__ , ix1 , pte1 );
	580	return EINVAL;
	581	}
	582
	583	// compute PPN of PT2 base
	584	pt2_ppn = TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	585
	586	// compute pointer on PT2 base
	587	pt2 = (uint32_t*)ppm_ppn2base( pt2_ppn );
	588	}
	589
	590	// from here we have the PT2 pointer
	591
	592	// compute pointer on PTE2
	593	pte2_ptr = &pt2[2 * ix2];
	594
	595	// try to atomically lock the PTE2 until success
	596	do
	597	{
	598	// busy waiting until GPT_LOCK == 0
	599	do
	600	{
	601	attr = *pte2_ptr;
	602	hal_rdbar();
	603	}
	604	while( (attr & GPT_LOCKED) != 0 );
	605
	606	// try to set the GPT_LOCK wit a CAS
	607	atomic = hal_atomic_cas( (void*)pte2_ptr, attr , (attr \| GPT_LOCKED) );
	608	}
	609	while( atomic == 0 );
	610
	611	return 0;
	612	} // end hal_gpt_lock_pte()
	613
	614	////////////////////////////////////////
	615	error_t hal_gpt_unlock_pte( gpt_t * gpt,
	616	vpn_t vpn )
	617	{
	618	uint32_t * pt1; // PT1 base address
	619	uint32_t pte1; // value of PT1 entry
	620
	621	uint32_t * pt2; // PT2 base address
	622	ppn_t pt2_ppn; // PPN of PT2 page if missing PT2
	623	uint32_t * pte2_ptr; // address of PT2 entry
	624
	625	uint32_t attr; // PTE2 attribute
	626
	627	// compute indexes in P1 and PT2
	628	uint32_t ix1 = TSAR_MMU_IX1_FROM_VPN( vpn ); // index in PT1
	629	uint32_t ix2 = TSAR_MMU_IX2_FROM_VPN( vpn ); // index in PT2
	630
	631	// get pointer on PT1 base
	632	pt1 = (uint32_t*)gpt->ptr;
	633
	634	// get PTE1
	635	pte1 = pt1[ix1];
	636
	637	// check PTE1 present and small page
	638	if( ((pte1 & GPT_MAPPED) == 0) \|\| ((pte1 & GPT_SMALL) == 0) )
	639	{
	640	printk("\n[ERROR] in %s : try to unlock a big or undefined page / PT1[%d] = %x\n",
	641	__FUNCTION__ , ix1 , pte1 );
	642	return EINVAL;
	643	}
	644
	645	// get pointer on PT2 base
	646	pt2_ppn = TSAR_MMU_PPN_FROM_PTE1( pte1 );
	647	pt2 = ppm_ppn2base( pt2_ppn );
	648
	649	// get pointer on PTE2
	650	pte2_ptr = &pt2[2 * ix2];
	651
	652	// get PTE2_ATTR
	653	attr = *pte2_ptr;
	654
	655	// check PTE2 present and locked
	656	if( ((attr & GPT_MAPPED) == 0) \|\| ((attr & GPT_LOCKED) == 0) );
	657	{
	658	printk("\n[ERROR] in %s : try to unlock an undefined page / PT1[%d] = %x\n",
	659	__FUNCTION__ , ix1 , pte1 );
	660	return EINVAL;
	661	}
	662
	663	// reset GPT_LOCK
	664	*pte2_ptr = attr & !GPT_LOCKED;
	665
	666	return 0;
	667	} // end hal_gpt_unlock_pte()
	668
[23]	669	///////////////////////////////////////
	670	error_t hal_gpt_copy( gpt_t * dst_gpt,
	671	gpt_t * src_gpt,
	672	bool_t cow )
	673	{
	674	uint32_t ix1; // index in PT1
	675	uint32_t ix2; // index in PT2
[1]	676
[23]	677	uint32_t * src_pt1; // local pointer on PT1 for SRC_GPT
	678	uint32_t * dst_pt1; // local pointer on PT1 for DST_GPT
	679	uint32_t * dst_pt2; // local pointer on PT2 for DST_GPT
	680	uint32_t * src_pt2; // local pointer on PT2 for SRC_GPT
[1]	681
[23]	682	uint32_t pte1;
	683	uint32_t pte2_attr;
	684	uint32_t pte2_ppn;
	685	uint32_t pte2_writable;
[1]	686
[23]	687	page_t * page;
[1]	688
[23]	689	ppn_t src_pt2_ppn;
	690	ppn_t dst_pt2_ppn;
[1]	691
[23]	692	// get pointers on PT1 for src_gpt & dst_gpt
	693	src_pt1 = (uint32_t *)src_gpt->ptr;
	694	dst_pt1 = (uint32_t *)dst_gpt->ptr;
[1]	695
[23]	696	// scan the SRC_PT1
	697	for( ix1 = 0 ; ix1 < 2048 ; ix1++ )
	698	{
	699	pte1 = src_pt1[ix1];
	700	if( (pte1 & GPT_MAPPED) != 0 )
	701	{
	702	if( (pte1 & GPT_SMALL) == 0 ) // PTE1 => big kernel page
	703	{
	704	// big kernel pages are shared by all processes => copy it
	705	dst_pt1[ix1] = pte1;
	706	}
	707	else // PTD1 => smal pages
	708	{
	709	// allocate one physical page for a PT2 in DST_GPT
	710	kmem_req_t req;
	711	req.type = KMEM_PAGE;
	712	req.size = 0; // 1 small page
	713	req.flags = AF_KERNEL \| AF_ZERO;
	714	page = (page_t *)kmem_alloc( &req );
[1]	715
[23]	716	if( page == NULL )
	717	{
	718	// TODO release all memory allocated to DST_GPT
	719	printk("\n[ERROR] in %s : cannot allocate PT2\n", __FUNCTION__ );
	720	return ENOMEM;
	721	}
	722
	723	// get pointer on new PT2 in DST_GPT
	724	dst_pt2 = (uint32_t *)ppm_page2base( page );
	725
	726	// set a new PTD1 in DST_GPT
	727	dst_pt2_ppn = (ppn_t)ppm_page2ppn( page );
	728	dst_pt1[ix1] = TSAR_MMU_PRESENT \| TSAR_MMU_PTD1 \| dst_pt2_ppn;
	729
	730	// get pointer on PT2 in SRC_GPT
	731	src_pt2_ppn = (ppn_t)TSAR_MMU_PTBA_FROM_PTE1( pte1 );
	732	src_pt2 = (uint32_t *)ppm_ppn2base( src_pt2_ppn );
	733
	734	// scan the SRC_PT2
	735	for( ix2 = 0 ; ix2 < 512 ; ix2++ )
	736	{
	737	// get attr & ppn from PTE2
	738	pte2_attr = TSAR_MMU_ATTR_FROM_PTE2( src_pt2[2 * ix2] );
	739
	740	if( (pte2_attr & GPT_MAPPED) != 0 ) // valid PTE2 in SRC_GPT
	741	{
	742	// get GPT_WRITABLE & PPN
	743	pte2_writable = pte2_attr & GPT_WRITABLE;
	744	pte2_ppn = TSAR_MMU_PPN_FROM_PTE2( src_pt2[2 * ix2 + 1] );
	745
	746	// set a new PTE2 in DST_GPT
	747	dst_pt2[2*ix2] = pte2_attr;
	748	dst_pt2[2*ix2 + 1] = pte2_ppn;
	749
	750	// handle Copy-On-Write
	751	if( cow && pte2_writable )
	752	{
	753	// reset GPT_WRITABLE in both SRC_GPT and DST_GPT
	754	hal_atomic_and( &dst_pt2[2*ix2] , ~GPT_WRITABLE );
	755	hal_atomic_and( &src_pt2[2*ix2] , ~GPT_WRITABLE );
	756
	757	// register PG_COW in page descriptor
	758	page = ppm_ppn2page( pte2_ppn );
	759	hal_atomic_or( &page->flags , PG_COW );
	760	hal_atomic_add( &page->fork_nr , 1 );
	761	}
	762	}
	763	} // end loop on ix2
	764	}
	765	}
	766	} // end loop ix1
	767
	768	hal_wbflush();
	769
	770	return 0;
	771
	772	} // end hal_gpt_copy()
	773

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