arch/arm/lib/relocate.S

   1 /*
   2  *  relocate - common relocation function for ARM U-Boot
   3  *
   4  *  Copyright (c) 2013  Albert ARIBAUD <albert.u.boot@aribaud.net>
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <asm-offsets.h>
  10 #include <config.h>
  11 #include <linux/linkage.h>
  12
  13 /*
  14  * void relocate_code(addr_moni)
  15  *
  16  * This function relocates the monitor code.
  17  *
  18  * NOTE:
  19  * To prevent the code below from containing references with an R_ARM_ABS32
  20  * relocation record type, we never refer to linker-defined symbols directly.
  21  * Instead, we declare literals which contain their relative location with
  22  * respect to relocate_code, and at run time, add relocate_code back to them.
  23  */
  24
  25 ENTRY(relocate_code)
  26         ldr     r1, =__image_copy_start /* r1 <- SRC &__image_copy_start */
  27         subs    r4, r0, r1              /* r4 <- relocation offset */
  28         beq     relocate_done           /* skip relocation */
  29         ldr     r2, =__image_copy_end   /* r2 <- SRC &__image_copy_end */
  30
  31 copy_loop:
  32         ldmia   r1!, {r10-r11}          /* copy from source address [r1]    */
  33         stmia   r0!, {r10-r11}          /* copy to   target address [r0]    */
  34         cmp     r1, r2                  /* until source end address [r2]    */
  35         blo     copy_loop
  36
  37         /*
  38          * fix .rel.dyn relocations
  39          */
  40         ldr     r2, =__rel_dyn_start    /* r2 <- SRC &__rel_dyn_start */
  41         ldr     r3, =__rel_dyn_end      /* r3 <- SRC &__rel_dyn_end */
  42 fixloop:
  43         ldmia   r2!, {r0-r1}            /* (r0,r1) <- (SRC location,fixup) */
  44         and     r1, r1, #0xff
  45         cmp     r1, #23                 /* relative fixup? */
  46         bne     fixnext
  47
  48         /* relative fix: increase location by offset */
  49         add     r0, r0, r4
  50         ldr     r1, [r0]
  51         add     r1, r1, r4
  52         str     r1, [r0]
  53 fixnext:
  54         cmp     r2, r3
  55         blo     fixloop
  56
  57         /*
  58          * Relocate the exception vectors
  59          */
  60 #ifdef CONFIG_HAS_VBAR
  61         /*
  62          * If the ARM processor has the security extensions,
  63          * use VBAR to relocate the exception vectors.
  64          */
  65         ldr     r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
  66         mcr     p15, 0, r0, c12, c0, 0  /* Set VBAR */
  67 #else
  68         /*
  69          * Copy the relocated exception vectors to the
  70          * correct address
  71          * CP15 c1 V bit gives us the location of the vectors:
  72          * 0x00000000 or 0xFFFF0000.
  73          */
  74         ldr     r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
  75         mrc     p15, 0, r2, c1, c0, 0   /* V bit (bit[13]) in CP15 c1 */
  76         ands    r2, r2, #(1 << 13)
  77         ldreq   r1, =0x00000000         /* If V=0 */
  78         ldrne   r1, =0xFFFF0000         /* If V=1 */
  79         ldmia   r0!, {r2-r8,r10}
  80         stmia   r1!, {r2-r8,r10}
  81         ldmia   r0!, {r2-r8,r10}
  82         stmia   r1!, {r2-r8,r10}
  83 #endif
  84
  85 relocate_done:
  86
  87 #ifdef __XSCALE__
  88         /*
  89          * On xscale, icache must be invalidated and write buffers drained,
  90          * even with cache disabled - 4.2.7 of xscale core developer's manual
  91          */
  92         mcr     p15, 0, r0, c7, c7, 0   /* invalidate icache */
  93         mcr     p15, 0, r0, c7, c10, 4  /* drain write buffer */
  94 #endif
  95
  96         /* ARMv4- don't know bx lr but the assembler fails to see that */
  97
  98 #ifdef __ARM_ARCH_4__
  99         mov     pc, lr
 100 #else
 101         bx      lr
 102 #endif
 103
 104 ENDPROC(relocate_code)