cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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jump_label.h (1655B)


      1/* SPDX-License-Identifier: GPL-2.0 */
      2/* Copyright (C) 2018 Cadence Design Systems Inc. */
      3
      4#ifndef _ASM_XTENSA_JUMP_LABEL_H
      5#define _ASM_XTENSA_JUMP_LABEL_H
      6
      7#ifndef __ASSEMBLY__
      8
      9#include <linux/types.h>
     10
     11#define JUMP_LABEL_NOP_SIZE 3
     12
     13static __always_inline bool arch_static_branch(struct static_key *key,
     14					       bool branch)
     15{
     16	asm_volatile_goto("1:\n\t"
     17			  "_nop\n\t"
     18			  ".pushsection __jump_table,  \"aw\"\n\t"
     19			  ".word 1b, %l[l_yes], %c0\n\t"
     20			  ".popsection\n\t"
     21			  : :  "i" (&((char *)key)[branch]) :  : l_yes);
     22
     23	return false;
     24l_yes:
     25	return true;
     26}
     27
     28static __always_inline bool arch_static_branch_jump(struct static_key *key,
     29						    bool branch)
     30{
     31	/*
     32	 * Xtensa assembler will mark certain points in the code
     33	 * as unreachable, so that later assembler or linker relaxation
     34	 * passes could use them. A spot right after the J instruction
     35	 * is one such point. Assembler and/or linker may insert padding
     36	 * or literals here, breaking code flow in case the J instruction
     37	 * is later replaced with NOP. Put a label right after the J to
     38	 * make it reachable and wrap both into a no-transform block
     39	 * to avoid any assembler interference with this.
     40	 */
     41	asm_volatile_goto("1:\n\t"
     42			  ".begin no-transform\n\t"
     43			  "_j %l[l_yes]\n\t"
     44			  "2:\n\t"
     45			  ".end no-transform\n\t"
     46			  ".pushsection __jump_table,  \"aw\"\n\t"
     47			  ".word 1b, %l[l_yes], %c0\n\t"
     48			  ".popsection\n\t"
     49			  : :  "i" (&((char *)key)[branch]) :  : l_yes);
     50
     51	return false;
     52l_yes:
     53	return true;
     54}
     55
     56typedef u32 jump_label_t;
     57
     58struct jump_entry {
     59	jump_label_t code;
     60	jump_label_t target;
     61	jump_label_t key;
     62};
     63
     64#endif  /* __ASSEMBLY__ */
     65#endif