/* 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 __INIT ENTRY(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_SHIFT ENTRY(external_cmdline_buffer) .fill _PAGE_SIZE,1,0 .data .p2align PAGE_SHIFT ENTRY(empty_zero_page) .fill _PAGE_SIZE,1,0
