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Diffstat (limited to '')
| -rw-r--r-- | arch/hexagon/kernel/head.S | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/arch/hexagon/kernel/head.S b/arch/hexagon/kernel/head.S new file mode 100644 index 000000000..0b016308c --- /dev/null +++ b/arch/hexagon/kernel/head.S @@ -0,0 +1,223 @@ +/* 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 |