/* SPDX-License-Identifier: GPL-2.0-only *//* * Early kernel startup code for Hexagon * * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved. */ #include <linux/linkage.h>#include <linux/init.h>#include <asm/asm-offsets.h>#include <asm/mem-layout.h>#include <asm/vm_mmu.h>#include <asm/page.h>#include <asm/hexagon_vm.h> #define SEGTABLE_ENTRIES #0x0e0 	__INITENTRY(stext)	/*	 * VMM will already have set up true vector page, MMU, etc.	 * To set up initial kernel identity map, we have to pass	 * the VMM a pointer to some canonical page tables. In	 * this implementation, we're assuming that we've got	 * them precompiled. Generate value in R24, as we'll need	 * it again shortly.	 */	r24.L = #LO(swapper_pg_dir)	r24.H = #HI(swapper_pg_dir) 	/*	 * Symbol is kernel segment address, but we need	 * the logical/physical address.	 */	r25 = pc;	r2.h = #0xffc0;	r2.l = #0x0000;	r25 = and(r2,r25);	/*  R25 holds PHYS_OFFSET now  */	r1.h = #HI(PAGE_OFFSET);	r1.l = #LO(PAGE_OFFSET);	r24 = sub(r24,r1);	/* swapper_pg_dir - PAGE_OFFSET */	r24 = add(r24,r25);	/* + PHYS_OFFSET */ 	r0 = r24;  /* aka __pa(swapper_pg_dir)  */ 	/*	 * Initialize page dir to make the virtual and physical	 * addresses where the kernel was loaded be identical.	 * Done in 4MB chunks.	 */#define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X	\		  | __HEXAGON_C_WB_L2 << 6			\		  | __HVM_PDE_S_4MB) 	/*	 * Get number of VA=PA entries; only really needed for jump	 * to hyperspace; gets blown away immediately after	 */ 	{		r1.l = #LO(_end);		r2.l = #LO(stext);		r3 = #1;	}	{		r1.h = #HI(_end);		r2.h = #HI(stext);		r3 = asl(r3, #22);	}	{		r1 = sub(r1, r2);		r3 = add(r3, #-1);	}  /* r1 =  _end - stext  */	r1 = add(r1, r3);  /*  + (4M-1) */	r26 = lsr(r1, #22); /*  / 4M = # of entries */ 	r1 = r25;	r2.h = #0xffc0;	r2.l = #0x0000;		/* round back down to 4MB boundary  */	r1 = and(r1,r2);	r2 = lsr(r1, #22)	/* 4MB page number		*/	r2 = asl(r2, #2)	/* times sizeof(PTE) (4bytes)	*/	r0 = add(r0,r2)		/* r0 = address of correct PTE	*/	r2 = #PTE_BITS	r1 = add(r1,r2)		/* r1 = 4MB PTE for the first entry	*/	r2.h = #0x0040	r2.l = #0x0000		/* 4MB increments */	loop0(1f,r26);1:	memw(r0 ++ #4) = r1	{ r1 = add(r1, r2); } :endloop0 	/*  Also need to overwrite the initial 0xc0000000 entries  */	/*  PAGE_OFFSET >> (4MB shift - 4 bytes per entry shift)  */	R1.H = #HI(PAGE_OFFSET >> (22 - 2))	R1.L = #LO(PAGE_OFFSET >> (22 - 2)) 	r0 = add(r1, r24);	/* advance to 0xc0000000 entry */	r1 = r25;	r2.h = #0xffc0;	r2.l = #0x0000;		/* round back down to 4MB boundary  */	r1 = and(r1,r2);	/* for huge page */	r2 = #PTE_BITS	r1 = add(r1,r2);	r2.h = #0x0040	r2.l = #0x0000		/* 4MB increments */ 	loop0(1f,SEGTABLE_ENTRIES);1:	memw(r0 ++ #4) = r1;	{ r1 = add(r1,r2); } :endloop0 	r0 = r24; 	/*	 * The subroutine wrapper around the virtual instruction touches	 * no memory, so we should be able to use it even here.	 * Note that in this version, R1 and R2 get "clobbered"; see	 * vm_ops.S	 */	r1 = #VM_TRANS_TYPE_TABLE	call	__vmnewmap; 	/*  Jump into virtual address range.  */ 	r31.h = #hi(__head_s_vaddr_target)	r31.l = #lo(__head_s_vaddr_target)	jumpr r31 	/*  Insert trippy space effects.  */ __head_s_vaddr_target:	/*	 * Tear down VA=PA translation now that we are running	 * in kernel virtual space.	 */	r0 = #__HVM_PDE_S_INVALID 	r1.h = #0xffc0;	r1.l = #0x0000;	r2 = r25;		/* phys_offset */	r2 = and(r1,r2); 	r1.l = #lo(swapper_pg_dir)	r1.h = #hi(swapper_pg_dir)	r2 = lsr(r2, #22)	/* 4MB page number		*/	r2 = asl(r2, #2)	/* times sizeof(PTE) (4bytes)	*/	r1 = add(r1,r2);	loop0(1f,r26) 1:	{		memw(R1 ++ #4) = R0	}:endloop0 	r0 = r24	r1 = #VM_TRANS_TYPE_TABLE	call __vmnewmap 	/*  Go ahead and install the trap0 return so angel calls work  */	r0.h = #hi(_K_provisional_vec)	r0.l = #lo(_K_provisional_vec)	call __vmsetvec 	/*	 * OK, at this point we should start to be much more careful,	 * we're going to enter C code and start touching memory	 * in all sorts of places.	 * This means:	 *      SGP needs to be OK	 *	Need to lock shared resources	 *	A bunch of other things that will cause	 * 	all kinds of painful bugs	 */ 	/*	 * Stack pointer should be pointed at the init task's	 * thread stack, which should have been declared in arch/init_task.c.	 * So uhhhhh...	 * It's accessible via the init_thread_union, which is a union	 * of a thread_info struct and a stack; of course, the top	 * of the stack is not for you.  The end of the stack	 * is simply init_thread_union + THREAD_SIZE.	 */ 	{r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); }	{r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); } 	/*  initialize the register used to point to current_thread_info */	/*  Fixme:  THREADINFO_REG can't be R2 because of that memset thing. */	{r29 = add(r29,r0); THREADINFO_REG = r29; } 	/*  Hack:  zero bss; */	{ r0.L = #LO(__bss_start);  r1 = #0; r2.l = #LO(__bss_stop); }	{ r0.H = #HI(__bss_start);           r2.h = #HI(__bss_stop); } 	r2 = sub(r2,r0);	call memset; 	/*  Set PHYS_OFFSET; should be in R25 */#ifdef CONFIG_HEXAGON_PHYS_OFFSET	r0.l = #LO(__phys_offset);	r0.h = #HI(__phys_offset);	memw(r0) = r25;#endif 	/* Time to make the doughnuts.   */	call start_kernel 	/*	 * Should not reach here.	 */1:	jump 1b .p2align PAGE_SHIFTENTRY(external_cmdline_buffer)        .fill _PAGE_SIZE,1,0