arch/x86/lib/retpoline.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 #include <linux/stringify.h>
   4 #include <linux/linkage.h>
   5 #include <asm/dwarf2.h>
   6 #include <asm/cpufeatures.h>
   7 #include <asm/alternative-asm.h>
   8 #include <asm/nospec-branch.h>
   9
  10 .macro THUNK reg
  11         .section .text.__x86.indirect_thunk
  12
  13 ENTRY(__x86_indirect_thunk_\reg)
  14         CFI_STARTPROC
  15         JMP_NOSPEC %\reg
  16         CFI_ENDPROC
  17 ENDPROC(__x86_indirect_thunk_\reg)
  18 .endm
  19
  20 /*
  21  * Despite being an assembler file we can't just use .irp here
  22  * because __KSYM_DEPS__ only uses the C preprocessor and would
  23  * only see one instance of "__x86_indirect_thunk_\reg" rather
  24  * than one per register with the correct names. So we do it
  25  * the simple and nasty way...
  26  */
  27 #define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym)
  28 #define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
  29 #define GENERATE_THUNK(reg) THUNK reg ; EXPORT_THUNK(reg)
  30
  31 GENERATE_THUNK(_ASM_AX)
  32 GENERATE_THUNK(_ASM_BX)
  33 GENERATE_THUNK(_ASM_CX)
  34 GENERATE_THUNK(_ASM_DX)
  35 GENERATE_THUNK(_ASM_SI)
  36 GENERATE_THUNK(_ASM_DI)
  37 GENERATE_THUNK(_ASM_BP)
  38 #ifdef CONFIG_64BIT
  39 GENERATE_THUNK(r8)
  40 GENERATE_THUNK(r9)
  41 GENERATE_THUNK(r10)
  42 GENERATE_THUNK(r11)
  43 GENERATE_THUNK(r12)
  44 GENERATE_THUNK(r13)
  45 GENERATE_THUNK(r14)
  46 GENERATE_THUNK(r15)
  47 #endif