arch/mips/vdso/vdso.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Copyright (C) 2015 Imagination Technologies
   4  * Author: Alex Smith <alex.smith@imgtec.com>
   5  */
   6
   7 #include <asm/sgidefs.h>
   8
   9 #if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
  10
  11 /* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
  12 #define BUILD_VDSO32_64
  13 #undef CONFIG_64BIT
  14 #define CONFIG_32BIT 1
  15 #ifndef __ASSEMBLY__
  16 #include <asm-generic/atomic64.h>
  17 #endif
  18 #endif
  19
  20 #ifndef __ASSEMBLY__
  21
  22 #include <asm/asm.h>
  23 #include <asm/page.h>
  24 #include <asm/vdso.h>
  25
  26 static inline unsigned long get_vdso_base(void)
  27 {
  28         unsigned long addr;
  29
  30         /*
  31          * We can't use cpu_has_mips_r6 since it needs the cpu_data[]
  32          * kernel symbol.
  33          */
  34 #ifdef CONFIG_CPU_MIPSR6
  35         /*
  36          * lapc <symbol> is an alias to addiupc reg, <symbol> - .
  37          *
  38          * We can't use addiupc because there is no label-label
  39          * support for the addiupc reloc
  40          */
  41         __asm__("lapc   %0, _start                      \n"
  42                 : "=r" (addr) : :);
  43 #else
  44         /*
  45          * Get the base load address of the VDSO. We have to avoid generating
  46          * relocations and references to the GOT because ld.so does not peform
  47          * relocations on the VDSO. We use the current offset from the VDSO base
  48          * and perform a PC-relative branch which gives the absolute address in
  49          * ra, and take the difference. The assembler chokes on
  50          * "li %0, _start - .", so embed the offset as a word and branch over
  51          * it.
  52          *
  53          */
  54
  55         __asm__(
  56         "       .set push                               \n"
  57         "       .set noreorder                          \n"
  58         "       bal     1f                              \n"
  59         "        nop                                    \n"
  60         "       .word   _start - .                      \n"
  61         "1:     lw      %0, 0($31)                      \n"
  62         "       " STR(PTR_ADDU) " %0, $31, %0           \n"
  63         "       .set pop                                \n"
  64         : "=r" (addr)
  65         :
  66         : "$31");
  67 #endif /* CONFIG_CPU_MIPSR6 */
  68
  69         return addr;
  70 }
  71
  72 static inline const union mips_vdso_data *get_vdso_data(void)
  73 {
  74         return (const union mips_vdso_data *)(get_vdso_base() - PAGE_SIZE);
  75 }
  76
  77 #ifdef CONFIG_CLKSRC_MIPS_GIC
  78
  79 static inline void __iomem *get_gic(const union mips_vdso_data *data)
  80 {
  81         return (void __iomem *)data - PAGE_SIZE;
  82 }
  83
  84 #endif /* CONFIG_CLKSRC_MIPS_GIC */
  85
  86 #endif /* __ASSEMBLY__ */