1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Early kernel startup code for Hexagon
5 * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
8 #include <linux/linkage.h>
9 #include <linux/init.h>
10 #include <asm/asm-offsets.h>
11 #include <asm/mem-layout.h>
12 #include <asm/vm_mmu.h>
14 #include <asm/hexagon_vm.h>
16 #define SEGTABLE_ENTRIES #0x0e0
21 * VMM will already have set up true vector page, MMU, etc.
22 * To set up initial kernel identity map, we have to pass
23 * the VMM a pointer to some canonical page tables. In
24 * this implementation, we're assuming that we've got
25 * them precompiled. Generate value in R24, as we'll need
28 r24.L = #LO(swapper_pg_dir)
29 r24.H = #HI(swapper_pg_dir)
32 * Symbol is kernel segment address, but we need
33 * the logical/physical address.
38 r25 = and(r2,r25); /* R25 holds PHYS_OFFSET now */
39 r1.h = #HI(PAGE_OFFSET);
40 r1.l = #LO(PAGE_OFFSET);
41 r24 = sub(r24,r1); /* swapper_pg_dir - PAGE_OFFSET */
42 r24 = add(r24,r25); /* + PHYS_OFFSET */
44 r0 = r24; /* aka __pa(swapper_pg_dir) */
47 * Initialize page dir to make the virtual and physical
48 * addresses where the kernel was loaded be identical.
51 #define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X \
52 | __HEXAGON_C_WB_L2 << 6 \
56 * Get number of VA=PA entries; only really needed for jump
57 * to hyperspace; gets blown away immediately after
73 } /* r1 = _end - stext */
74 r1 = add(r1, r3); /* + (4M-1) */
75 r26 = lsr(r1, #22); /* / 4M = # of entries */
79 r2.l = #0x0000; /* round back down to 4MB boundary */
81 r2 = lsr(r1, #22) /* 4MB page number */
82 r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */
83 r0 = add(r0,r2) /* r0 = address of correct PTE */
85 r1 = add(r1,r2) /* r1 = 4MB PTE for the first entry */
87 r2.l = #0x0000 /* 4MB increments */
91 { r1 = add(r1, r2); } :endloop0
93 /* Also need to overwrite the initial 0xc0000000 entries */
94 /* PAGE_OFFSET >> (4MB shift - 4 bytes per entry shift) */
95 R1.H = #HI(PAGE_OFFSET >> (22 - 2))
96 R1.L = #LO(PAGE_OFFSET >> (22 - 2))
98 r0 = add(r1, r24); /* advance to 0xc0000000 entry */
101 r2.l = #0x0000; /* round back down to 4MB boundary */
102 r1 = and(r1,r2); /* for huge page */
106 r2.l = #0x0000 /* 4MB increments */
108 loop0(1f,SEGTABLE_ENTRIES);
111 { r1 = add(r1,r2); } :endloop0
116 * The subroutine wrapper around the virtual instruction touches
117 * no memory, so we should be able to use it even here.
118 * Note that in this version, R1 and R2 get "clobbered"; see
121 r1 = #VM_TRANS_TYPE_TABLE
124 /* Jump into virtual address range. */
126 r31.h = #hi(__head_s_vaddr_target)
127 r31.l = #lo(__head_s_vaddr_target)
130 /* Insert trippy space effects. */
132 __head_s_vaddr_target:
134 * Tear down VA=PA translation now that we are running
135 * in kernel virtual space.
137 r0 = #__HVM_PDE_S_INVALID
141 r2 = r25; /* phys_offset */
144 r1.l = #lo(swapper_pg_dir)
145 r1.h = #hi(swapper_pg_dir)
146 r2 = lsr(r2, #22) /* 4MB page number */
147 r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */
157 r1 = #VM_TRANS_TYPE_TABLE
160 /* Go ahead and install the trap0 return so angel calls work */
161 r0.h = #hi(_K_provisional_vec)
162 r0.l = #lo(_K_provisional_vec)
166 * OK, at this point we should start to be much more careful,
167 * we're going to enter C code and start touching memory
168 * in all sorts of places.
171 * Need to lock shared resources
172 * A bunch of other things that will cause
173 * all kinds of painful bugs
177 * Stack pointer should be pointed at the init task's
178 * thread stack, which should have been declared in arch/init_task.c.
180 * It's accessible via the init_thread_union, which is a union
181 * of a thread_info struct and a stack; of course, the top
182 * of the stack is not for you. The end of the stack
183 * is simply init_thread_union + THREAD_SIZE.
186 {r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); }
187 {r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); }
189 /* initialize the register used to point to current_thread_info */
190 /* Fixme: THREADINFO_REG can't be R2 because of that memset thing. */
191 {r29 = add(r29,r0); THREADINFO_REG = r29; }
193 /* Hack: zero bss; */
194 { r0.L = #LO(__bss_start); r1 = #0; r2.l = #LO(__bss_stop); }
195 { r0.H = #HI(__bss_start); r2.h = #HI(__bss_stop); }
200 /* Set PHYS_OFFSET; should be in R25 */
201 #ifdef CONFIG_HEXAGON_PHYS_OFFSET
202 r0.l = #LO(__phys_offset);
203 r0.h = #HI(__phys_offset);
207 /* Time to make the doughnuts. */
211 * Should not reach here.
217 ENTRY(external_cmdline_buffer)
222 ENTRY(empty_zero_page)