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