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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_S390_ALTERNATIVE_H
#define _ASM_S390_ALTERNATIVE_H
#ifndef __ASSEMBLY__
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/stringify.h>
struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
u16 facility; /* facility bit set for replacement */
u8 instrlen; /* length of original instruction */
u8 replacementlen; /* length of new instruction */
} __packed;
void apply_alternative_instructions(void);
void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
/*
* |661: |662: |6620 |663:
* +-----------+---------------------+
* | oldinstr | oldinstr_padding |
* | +----------+----------+
* | | | |
* | | >6 bytes |6/4/2 nops|
* | |6 bytes jg----------->
* +-----------+---------------------+
* ^^ static padding ^^
*
* .altinstr_replacement section
* +---------------------+-----------+
* |6641: |6651:
* | alternative instr 1 |
* +-----------+---------+- - - - - -+
* |6642: |6652: |
* | alternative instr 2 | padding
* +---------------------+- - - - - -+
* ^ runtime ^
*
* .altinstructions section
* +---------------------------------+
* | alt_instr entries for each |
* | alternative instr |
* +---------------------------------+
*/
#define b_altinstr(num) "664"#num
#define e_altinstr(num) "665"#num
#define e_oldinstr_pad_end "663"
#define oldinstr_len "662b-661b"
#define oldinstr_total_len e_oldinstr_pad_end"b-661b"
#define altinstr_len(num) e_altinstr(num)"b-"b_altinstr(num)"b"
#define oldinstr_pad_len(num) \
"-(((" altinstr_len(num) ")-(" oldinstr_len ")) > 0) * " \
"((" altinstr_len(num) ")-(" oldinstr_len "))"
#define INSTR_LEN_SANITY_CHECK(len) \
".if " len " > 254\n" \
"\t.error \"cpu alternatives does not support instructions " \
"blocks > 254 bytes\"\n" \
".endif\n" \
".if (" len ") %% 2\n" \
"\t.error \"cpu alternatives instructions length is odd\"\n" \
".endif\n"
#define OLDINSTR_PADDING(oldinstr, num) \
".if " oldinstr_pad_len(num) " > 6\n" \
"\tjg " e_oldinstr_pad_end "f\n" \
"6620:\n" \
"\t.fill (" oldinstr_pad_len(num) " - (6620b-662b)) / 2, 2, 0x0700\n" \
".else\n" \
"\t.fill " oldinstr_pad_len(num) " / 6, 6, 0xc0040000\n" \
"\t.fill " oldinstr_pad_len(num) " %% 6 / 4, 4, 0x47000000\n" \
"\t.fill " oldinstr_pad_len(num) " %% 6 %% 4 / 2, 2, 0x0700\n" \
".endif\n"
#define OLDINSTR(oldinstr, num) \
"661:\n\t" oldinstr "\n662:\n" \
OLDINSTR_PADDING(oldinstr, num) \
e_oldinstr_pad_end ":\n" \
INSTR_LEN_SANITY_CHECK(oldinstr_len)
#define OLDINSTR_2(oldinstr, num1, num2) \
"661:\n\t" oldinstr "\n662:\n" \
".if " altinstr_len(num1) " < " altinstr_len(num2) "\n" \
OLDINSTR_PADDING(oldinstr, num2) \
".else\n" \
OLDINSTR_PADDING(oldinstr, num1) \
".endif\n" \
e_oldinstr_pad_end ":\n" \
INSTR_LEN_SANITY_CHECK(oldinstr_len)
#define ALTINSTR_ENTRY(facility, num) \
"\t.long 661b - .\n" /* old instruction */ \
"\t.long " b_altinstr(num)"b - .\n" /* alt instruction */ \
"\t.word " __stringify(facility) "\n" /* facility bit */ \
"\t.byte " oldinstr_total_len "\n" /* source len */ \
"\t.byte " altinstr_len(num) "\n" /* alt instruction len */
#define ALTINSTR_REPLACEMENT(altinstr, num) /* replacement */ \
b_altinstr(num)":\n\t" altinstr "\n" e_altinstr(num) ":\n" \
INSTR_LEN_SANITY_CHECK(altinstr_len(num))
/* alternative assembly primitive: */
#define ALTERNATIVE(oldinstr, altinstr, facility) \
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(altinstr, 1) \
".popsection\n" \
OLDINSTR(oldinstr, 1) \
".pushsection .altinstructions,\"a\"\n" \
ALTINSTR_ENTRY(facility, 1) \
".popsection\n"
#define ALTERNATIVE_2(oldinstr, altinstr1, facility1, altinstr2, facility2)\
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(altinstr1, 1) \
ALTINSTR_REPLACEMENT(altinstr2, 2) \
".popsection\n" \
OLDINSTR_2(oldinstr, 1, 2) \
".pushsection .altinstructions,\"a\"\n" \
ALTINSTR_ENTRY(facility1, 1) \
ALTINSTR_ENTRY(facility2, 2) \
".popsection\n"
/*
* Alternative instructions for different CPU types or capabilities.
*
* This allows to use optimized instructions even on generic binary
* kernels.
*
* oldinstr is padded with jump and nops at compile time if altinstr is
* longer. altinstr is padded with jump and nops at run-time during patching.
*
* For non barrier like inlines please define new variants
* without volatile and memory clobber.
*/
#define alternative(oldinstr, altinstr, facility) \
asm volatile(ALTERNATIVE(oldinstr, altinstr, facility) : : : "memory")
#define alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2) \
asm volatile(ALTERNATIVE_2(oldinstr, altinstr1, facility1, \
altinstr2, facility2) ::: "memory")
#endif /* __ASSEMBLY__ */
#endif /* _ASM_S390_ALTERNATIVE_H */
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