472 lines
15 KiB
C
472 lines
15 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_ALTERNATIVE_H
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#define _ASM_X86_ALTERNATIVE_H
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#include <linux/types.h>
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#include <linux/stringify.h>
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#include <asm/asm.h>
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#define ALT_FLAGS_SHIFT 16
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#define ALT_FLAG_NOT (1 << 0)
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#define ALT_NOT(feature) ((ALT_FLAG_NOT << ALT_FLAGS_SHIFT) | (feature))
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#ifndef __ASSEMBLY__
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#include <linux/stddef.h>
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/*
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* Alternative inline assembly for SMP.
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*
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* The LOCK_PREFIX macro defined here replaces the LOCK and
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* LOCK_PREFIX macros used everywhere in the source tree.
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*
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* SMP alternatives use the same data structures as the other
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* alternatives and the X86_FEATURE_UP flag to indicate the case of a
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* UP system running a SMP kernel. The existing apply_alternatives()
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* works fine for patching a SMP kernel for UP.
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*
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* The SMP alternative tables can be kept after boot and contain both
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* UP and SMP versions of the instructions to allow switching back to
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* SMP at runtime, when hotplugging in a new CPU, which is especially
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* useful in virtualized environments.
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*
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* The very common lock prefix is handled as special case in a
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* separate table which is a pure address list without replacement ptr
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* and size information. That keeps the table sizes small.
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*/
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#ifdef CONFIG_SMP
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#define LOCK_PREFIX_HERE \
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".pushsection .smp_locks,\"a\"\n" \
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".balign 4\n" \
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".long 671f - .\n" /* offset */ \
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".popsection\n" \
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"671:"
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#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "
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#else /* ! CONFIG_SMP */
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#define LOCK_PREFIX_HERE ""
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#define LOCK_PREFIX ""
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#endif
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/*
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* objtool annotation to ignore the alternatives and only consider the original
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* instruction(s).
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*/
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#define ANNOTATE_IGNORE_ALTERNATIVE \
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"999:\n\t" \
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".pushsection .discard.ignore_alts\n\t" \
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".long 999b - .\n\t" \
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".popsection\n\t"
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/*
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* The patching flags are part of the upper bits of the @ft_flags parameter when
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* specifying them. The split is currently like this:
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*
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* [31... flags ...16][15... CPUID feature bit ...0]
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*
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* but since this is all hidden in the macros argument being split, those fields can be
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* extended in the future to fit in a u64 or however the need arises.
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*/
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struct alt_instr {
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s32 instr_offset; /* original instruction */
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s32 repl_offset; /* offset to replacement instruction */
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union {
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struct {
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u32 cpuid: 16; /* CPUID bit set for replacement */
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u32 flags: 16; /* patching control flags */
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};
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u32 ft_flags;
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};
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u8 instrlen; /* length of original instruction */
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u8 replacementlen; /* length of new instruction */
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} __packed;
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/*
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* Debug flag that can be tested to see whether alternative
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* instructions were patched in already:
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*/
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extern int alternatives_patched;
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extern void alternative_instructions(void);
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extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
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extern void apply_retpolines(s32 *start, s32 *end);
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extern void apply_returns(s32 *start, s32 *end);
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extern void apply_seal_endbr(s32 *start, s32 *end);
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extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
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s32 *start_cfi, s32 *end_cfi);
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struct module;
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struct paravirt_patch_site;
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struct callthunk_sites {
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s32 *call_start, *call_end;
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struct paravirt_patch_site *pv_start, *pv_end;
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};
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#ifdef CONFIG_CALL_THUNKS
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extern void callthunks_patch_builtin_calls(void);
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extern void callthunks_patch_module_calls(struct callthunk_sites *sites,
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struct module *mod);
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extern void *callthunks_translate_call_dest(void *dest);
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extern int x86_call_depth_emit_accounting(u8 **pprog, void *func);
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#else
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static __always_inline void callthunks_patch_builtin_calls(void) {}
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static __always_inline void
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callthunks_patch_module_calls(struct callthunk_sites *sites,
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struct module *mod) {}
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static __always_inline void *callthunks_translate_call_dest(void *dest)
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{
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return dest;
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}
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static __always_inline int x86_call_depth_emit_accounting(u8 **pprog,
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void *func)
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{
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return 0;
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}
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#endif
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#ifdef CONFIG_SMP
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extern void alternatives_smp_module_add(struct module *mod, char *name,
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void *locks, void *locks_end,
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void *text, void *text_end);
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extern void alternatives_smp_module_del(struct module *mod);
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extern void alternatives_enable_smp(void);
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extern int alternatives_text_reserved(void *start, void *end);
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extern bool skip_smp_alternatives;
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#else
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static inline void alternatives_smp_module_add(struct module *mod, char *name,
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void *locks, void *locks_end,
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void *text, void *text_end) {}
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static inline void alternatives_smp_module_del(struct module *mod) {}
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static inline void alternatives_enable_smp(void) {}
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static inline int alternatives_text_reserved(void *start, void *end)
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{
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return 0;
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}
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#endif /* CONFIG_SMP */
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#define b_replacement(num) "664"#num
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#define e_replacement(num) "665"#num
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#define alt_end_marker "663"
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#define alt_slen "662b-661b"
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#define alt_total_slen alt_end_marker"b-661b"
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#define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f"
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#define OLDINSTR(oldinstr, num) \
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"# ALT: oldnstr\n" \
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"661:\n\t" oldinstr "\n662:\n" \
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"# ALT: padding\n" \
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".skip -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \
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"((" alt_rlen(num) ")-(" alt_slen ")),0x90\n" \
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alt_end_marker ":\n"
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/*
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* gas compatible max based on the idea from:
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* http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
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*
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* The additional "-" is needed because gas uses a "true" value of -1.
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*/
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#define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") < (" b ")))))"
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/*
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* Pad the second replacement alternative with additional NOPs if it is
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* additionally longer than the first replacement alternative.
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*/
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#define OLDINSTR_2(oldinstr, num1, num2) \
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"# ALT: oldinstr2\n" \
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"661:\n\t" oldinstr "\n662:\n" \
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"# ALT: padding2\n" \
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".skip -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \
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"(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n" \
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alt_end_marker ":\n"
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#define OLDINSTR_3(oldinsn, n1, n2, n3) \
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"# ALT: oldinstr3\n" \
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"661:\n\t" oldinsn "\n662:\n" \
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"# ALT: padding3\n" \
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".skip -((" alt_max_short(alt_max_short(alt_rlen(n1), alt_rlen(n2)), alt_rlen(n3)) \
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" - (" alt_slen ")) > 0) * " \
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"(" alt_max_short(alt_max_short(alt_rlen(n1), alt_rlen(n2)), alt_rlen(n3)) \
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" - (" alt_slen ")), 0x90\n" \
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alt_end_marker ":\n"
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#define ALTINSTR_ENTRY(ft_flags, num) \
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" .long 661b - .\n" /* label */ \
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" .long " b_replacement(num)"f - .\n" /* new instruction */ \
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" .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
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" .byte " alt_total_slen "\n" /* source len */ \
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" .byte " alt_rlen(num) "\n" /* replacement len */
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#define ALTINSTR_REPLACEMENT(newinstr, num) /* replacement */ \
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"# ALT: replacement " #num "\n" \
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b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n"
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/* alternative assembly primitive: */
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#define ALTERNATIVE(oldinstr, newinstr, ft_flags) \
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OLDINSTR(oldinstr, 1) \
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".pushsection .altinstructions,\"a\"\n" \
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ALTINSTR_ENTRY(ft_flags, 1) \
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".popsection\n" \
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".pushsection .altinstr_replacement, \"ax\"\n" \
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ALTINSTR_REPLACEMENT(newinstr, 1) \
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".popsection\n"
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#define ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \
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OLDINSTR_2(oldinstr, 1, 2) \
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".pushsection .altinstructions,\"a\"\n" \
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ALTINSTR_ENTRY(ft_flags1, 1) \
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ALTINSTR_ENTRY(ft_flags2, 2) \
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".popsection\n" \
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".pushsection .altinstr_replacement, \"ax\"\n" \
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ALTINSTR_REPLACEMENT(newinstr1, 1) \
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ALTINSTR_REPLACEMENT(newinstr2, 2) \
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".popsection\n"
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/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */
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#define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
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ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \
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newinstr_yes, ft_flags)
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#define ALTERNATIVE_3(oldinsn, newinsn1, ft_flags1, newinsn2, ft_flags2, \
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newinsn3, ft_flags3) \
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OLDINSTR_3(oldinsn, 1, 2, 3) \
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".pushsection .altinstructions,\"a\"\n" \
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ALTINSTR_ENTRY(ft_flags1, 1) \
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ALTINSTR_ENTRY(ft_flags2, 2) \
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ALTINSTR_ENTRY(ft_flags3, 3) \
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".popsection\n" \
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".pushsection .altinstr_replacement, \"ax\"\n" \
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ALTINSTR_REPLACEMENT(newinsn1, 1) \
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ALTINSTR_REPLACEMENT(newinsn2, 2) \
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ALTINSTR_REPLACEMENT(newinsn3, 3) \
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".popsection\n"
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/*
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* Alternative instructions for different CPU types or capabilities.
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*
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* This allows to use optimized instructions even on generic binary
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* kernels.
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*
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* length of oldinstr must be longer or equal the length of newinstr
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* It can be padded with nops as needed.
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*
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* For non barrier like inlines please define new variants
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* without volatile and memory clobber.
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*/
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#define alternative(oldinstr, newinstr, ft_flags) \
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asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) : : : "memory")
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#define alternative_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \
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asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) ::: "memory")
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#define alternative_ternary(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
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asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) ::: "memory")
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/*
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* Alternative inline assembly with input.
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*
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* Peculiarities:
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* No memory clobber here.
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* Argument numbers start with 1.
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* Leaving an unused argument 0 to keep API compatibility.
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*/
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#define alternative_input(oldinstr, newinstr, ft_flags, input...) \
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asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \
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: : "i" (0), ## input)
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/*
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* This is similar to alternative_input. But it has two features and
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* respective instructions.
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*
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* If CPU has feature2, newinstr2 is used.
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* Otherwise, if CPU has feature1, newinstr1 is used.
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* Otherwise, oldinstr is used.
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*/
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#define alternative_input_2(oldinstr, newinstr1, ft_flags1, newinstr2, \
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ft_flags2, input...) \
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asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, \
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newinstr2, ft_flags2) \
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: : "i" (0), ## input)
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/* Like alternative_input, but with a single output argument */
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#define alternative_io(oldinstr, newinstr, ft_flags, output, input...) \
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asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \
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: output : "i" (0), ## input)
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/* Like alternative_io, but for replacing a direct call with another one. */
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#define alternative_call(oldfunc, newfunc, ft_flags, output, input...) \
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asm_inline volatile (ALTERNATIVE("call %P[old]", "call %P[new]", ft_flags) \
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: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
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/*
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* Like alternative_call, but there are two features and respective functions.
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* If CPU has feature2, function2 is used.
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* Otherwise, if CPU has feature1, function1 is used.
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* Otherwise, old function is used.
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*/
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#define alternative_call_2(oldfunc, newfunc1, ft_flags1, newfunc2, ft_flags2, \
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output, input...) \
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asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", ft_flags1,\
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"call %P[new2]", ft_flags2) \
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: output, ASM_CALL_CONSTRAINT \
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: [old] "i" (oldfunc), [new1] "i" (newfunc1), \
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[new2] "i" (newfunc2), ## input)
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/*
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* use this macro(s) if you need more than one output parameter
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* in alternative_io
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*/
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#define ASM_OUTPUT2(a...) a
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/*
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* use this macro if you need clobbers but no inputs in
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* alternative_{input,io,call}()
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*/
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#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr
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#else /* __ASSEMBLY__ */
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#ifdef CONFIG_SMP
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.macro LOCK_PREFIX
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672: lock
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.pushsection .smp_locks,"a"
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.balign 4
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.long 672b - .
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.popsection
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.endm
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#else
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.macro LOCK_PREFIX
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.endm
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#endif
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/*
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* objtool annotation to ignore the alternatives and only consider the original
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* instruction(s).
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*/
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.macro ANNOTATE_IGNORE_ALTERNATIVE
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.Lannotate_\@:
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.pushsection .discard.ignore_alts
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.long .Lannotate_\@ - .
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.popsection
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.endm
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/*
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* Issue one struct alt_instr descriptor entry (need to put it into
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* the section .altinstructions, see below). This entry contains
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* enough information for the alternatives patching code to patch an
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* instruction. See apply_alternatives().
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*/
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.macro altinstr_entry orig alt ft_flags orig_len alt_len
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.long \orig - .
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.long \alt - .
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.4byte \ft_flags
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.byte \orig_len
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.byte \alt_len
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.endm
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/*
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* Define an alternative between two instructions. If @feature is
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* present, early code in apply_alternatives() replaces @oldinstr with
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* @newinstr. ".skip" directive takes care of proper instruction padding
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* in case @newinstr is longer than @oldinstr.
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*/
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.macro ALTERNATIVE oldinstr, newinstr, ft_flags
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140:
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\oldinstr
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141:
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.skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
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142:
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.pushsection .altinstructions,"a"
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altinstr_entry 140b,143f,\ft_flags,142b-140b,144f-143f
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.popsection
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.pushsection .altinstr_replacement,"ax"
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143:
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\newinstr
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144:
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.popsection
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.endm
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#define old_len 141b-140b
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#define new_len1 144f-143f
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#define new_len2 145f-144f
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#define new_len3 146f-145f
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/*
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* gas compatible max based on the idea from:
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* http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
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*
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* The additional "-" is needed because gas uses a "true" value of -1.
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*/
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#define alt_max_2(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
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#define alt_max_3(a, b, c) (alt_max_2(alt_max_2(a, b), c))
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/*
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* Same as ALTERNATIVE macro above but for two alternatives. If CPU
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* has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
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* @feature2, it replaces @oldinstr with @feature2.
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*/
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.macro ALTERNATIVE_2 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2
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140:
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\oldinstr
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141:
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.skip -((alt_max_2(new_len1, new_len2) - (old_len)) > 0) * \
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(alt_max_2(new_len1, new_len2) - (old_len)),0x90
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142:
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.pushsection .altinstructions,"a"
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altinstr_entry 140b,143f,\ft_flags1,142b-140b,144f-143f
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altinstr_entry 140b,144f,\ft_flags2,142b-140b,145f-144f
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.popsection
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.pushsection .altinstr_replacement,"ax"
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143:
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\newinstr1
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144:
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\newinstr2
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145:
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.popsection
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.endm
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.macro ALTERNATIVE_3 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, newinstr3, ft_flags3
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140:
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\oldinstr
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141:
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.skip -((alt_max_3(new_len1, new_len2, new_len3) - (old_len)) > 0) * \
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(alt_max_3(new_len1, new_len2, new_len3) - (old_len)),0x90
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142:
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.pushsection .altinstructions,"a"
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altinstr_entry 140b,143f,\ft_flags1,142b-140b,144f-143f
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altinstr_entry 140b,144f,\ft_flags2,142b-140b,145f-144f
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altinstr_entry 140b,145f,\ft_flags3,142b-140b,146f-145f
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.popsection
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.pushsection .altinstr_replacement,"ax"
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143:
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\newinstr1
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144:
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\newinstr2
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145:
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\newinstr3
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146:
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.popsection
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|
.endm
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|
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/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */
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|
#define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
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ALTERNATIVE_2 oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \
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|
newinstr_yes, ft_flags
|
|
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#endif /* __ASSEMBLY__ */
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|
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|
#endif /* _ASM_X86_ALTERNATIVE_H */
|