73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _ASM_ARC_JUMP_LABEL_H
|
|
#define _ASM_ARC_JUMP_LABEL_H
|
|
|
|
#ifndef __ASSEMBLY__
|
|
|
|
#include <linux/stringify.h>
|
|
#include <linux/types.h>
|
|
|
|
#define JUMP_LABEL_NOP_SIZE 4
|
|
|
|
/*
|
|
* NOTE about '.balign 4':
|
|
*
|
|
* To make atomic update of patched instruction available we need to guarantee
|
|
* that this instruction doesn't cross L1 cache line boundary.
|
|
*
|
|
* As of today we simply align instruction which can be patched by 4 byte using
|
|
* ".balign 4" directive. In that case patched instruction is aligned with one
|
|
* 16-bit NOP_S if this is required.
|
|
* However 'align by 4' directive is much stricter than it actually required.
|
|
* It's enough that our 32-bit instruction don't cross L1 cache line boundary /
|
|
* L1 I$ fetch block boundary which can be achieved by using
|
|
* ".bundle_align_mode" assembler directive. That will save us from adding
|
|
* useless NOP_S padding in most of the cases.
|
|
*
|
|
* TODO: switch to ".bundle_align_mode" directive using whin it will be
|
|
* supported by ARC toolchain.
|
|
*/
|
|
|
|
static __always_inline bool arch_static_branch(struct static_key *key,
|
|
bool branch)
|
|
{
|
|
asm_volatile_goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
|
|
"1: \n"
|
|
"nop \n"
|
|
".pushsection __jump_table, \"aw\" \n"
|
|
".word 1b, %l[l_yes], %c0 \n"
|
|
".popsection \n"
|
|
: : "i" (&((char *)key)[branch]) : : l_yes);
|
|
|
|
return false;
|
|
l_yes:
|
|
return true;
|
|
}
|
|
|
|
static __always_inline bool arch_static_branch_jump(struct static_key *key,
|
|
bool branch)
|
|
{
|
|
asm_volatile_goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n"
|
|
"1: \n"
|
|
"b %l[l_yes] \n"
|
|
".pushsection __jump_table, \"aw\" \n"
|
|
".word 1b, %l[l_yes], %c0 \n"
|
|
".popsection \n"
|
|
: : "i" (&((char *)key)[branch]) : : l_yes);
|
|
|
|
return false;
|
|
l_yes:
|
|
return true;
|
|
}
|
|
|
|
typedef u32 jump_label_t;
|
|
|
|
struct jump_entry {
|
|
jump_label_t code;
|
|
jump_label_t target;
|
|
jump_label_t key;
|
|
};
|
|
|
|
#endif /* __ASSEMBLY__ */
|
|
#endif
|