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Diffstat (limited to 'arch/loongarch/include/asm/alternative.h')
| -rw-r--r-- | arch/loongarch/include/asm/alternative.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/arch/loongarch/include/asm/alternative.h b/arch/loongarch/include/asm/alternative.h new file mode 100644 index 000000000000..cee7b29785ab --- /dev/null +++ b/arch/loongarch/include/asm/alternative.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_ALTERNATIVE_H +#define _ASM_ALTERNATIVE_H + +#ifndef __ASSEMBLY__ + +#include <linux/types.h> +#include <linux/stddef.h> +#include <linux/stringify.h> +#include <asm/asm.h> + +struct alt_instr { + s32 instr_offset; /* offset to original instruction */ + s32 replace_offset; /* offset to replacement instruction */ + u16 feature; /* feature bit set for replacement */ + u8 instrlen; /* length of original instruction */ + u8 replacementlen; /* length of new instruction */ +} __packed; + +/* + * Debug flag that can be tested to see whether alternative + * instructions were patched in already: + */ +extern int alternatives_patched; +extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; + +extern void alternative_instructions(void); +extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); + +#define b_replacement(num) "664"#num +#define e_replacement(num) "665"#num + +#define alt_end_marker "663" +#define alt_slen "662b-661b" +#define alt_total_slen alt_end_marker"b-661b" +#define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f" + +#define __OLDINSTR(oldinstr, num) \ + "661:\n\t" oldinstr "\n662:\n" \ + ".fill -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \ + "((" alt_rlen(num) ")-(" alt_slen ")) / 4, 4, 0x03400000\n" + +#define OLDINSTR(oldinstr, num) \ + __OLDINSTR(oldinstr, num) \ + alt_end_marker ":\n" + +#define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") < (" b ")))))" + +/* + * Pad the second replacement alternative with additional NOPs if it is + * additionally longer than the first replacement alternative. + */ +#define OLDINSTR_2(oldinstr, num1, num2) \ + "661:\n\t" oldinstr "\n662:\n" \ + ".fill -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \ + "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) / 4, " \ + "4, 0x03400000\n" \ + alt_end_marker ":\n" + +#define ALTINSTR_ENTRY(feature, num) \ + " .long 661b - .\n" /* label */ \ + " .long " b_replacement(num)"f - .\n" /* new instruction */ \ + " .short " __stringify(feature) "\n" /* feature bit */ \ + " .byte " alt_total_slen "\n" /* source len */ \ + " .byte " alt_rlen(num) "\n" /* replacement len */ + +#define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \ + b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t" + +/* alternative assembly primitive: */ +#define ALTERNATIVE(oldinstr, newinstr, feature) \ + OLDINSTR(oldinstr, 1) \ + ".pushsection .altinstructions,\"a\"\n" \ + ALTINSTR_ENTRY(feature, 1) \ + ".popsection\n" \ + ".subsection 1\n" \ + ALTINSTR_REPLACEMENT(newinstr, feature, 1) \ + ".previous\n" + +#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\ + OLDINSTR_2(oldinstr, 1, 2) \ + ".pushsection .altinstructions,\"a\"\n" \ + ALTINSTR_ENTRY(feature1, 1) \ + ALTINSTR_ENTRY(feature2, 2) \ + ".popsection\n" \ + ".subsection 1\n" \ + ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \ + ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \ + ".previous\n" + +/* + * Alternative instructions for different CPU types or capabilities. + * + * This allows to use optimized instructions even on generic binary + * kernels. + * + * length of oldinstr must be longer or equal the length of newinstr + * It can be padded with nops as needed. + * + * For non barrier like inlines please define new variants + * without volatile and memory clobber. + */ +#define alternative(oldinstr, newinstr, feature) \ + (asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")) + +#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \ + (asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")) + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_ALTERNATIVE_H */ |