/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_ALTERNATIVE_H #define _ASM_X86_ALTERNATIVE_H #include <linux/types.h> #include <linux/stringify.h> #include <asm/asm.h> #define ALT_FLAGS_SHIFT … #define ALT_FLAG_NOT … #define ALT_NOT(feature) … #define ALT_FLAG_DIRECT_CALL … #define ALT_DIRECT_CALL(feature) … #define ALT_CALL_ALWAYS … #ifndef __ASSEMBLY__ #include <linux/stddef.h> /* * Alternative inline assembly for SMP. * * The LOCK_PREFIX macro defined here replaces the LOCK and * LOCK_PREFIX macros used everywhere in the source tree. * * SMP alternatives use the same data structures as the other * alternatives and the X86_FEATURE_UP flag to indicate the case of a * UP system running a SMP kernel. The existing apply_alternatives() * works fine for patching a SMP kernel for UP. * * The SMP alternative tables can be kept after boot and contain both * UP and SMP versions of the instructions to allow switching back to * SMP at runtime, when hotplugging in a new CPU, which is especially * useful in virtualized environments. * * The very common lock prefix is handled as special case in a * separate table which is a pure address list without replacement ptr * and size information. That keeps the table sizes small. */ #ifdef CONFIG_SMP #define LOCK_PREFIX_HERE … #define LOCK_PREFIX … #else /* ! CONFIG_SMP */ #define LOCK_PREFIX_HERE … #define LOCK_PREFIX … #endif /* * objtool annotation to ignore the alternatives and only consider the original * instruction(s). */ #define ANNOTATE_IGNORE_ALTERNATIVE … /* * The patching flags are part of the upper bits of the @ft_flags parameter when * specifying them. The split is currently like this: * * [31... flags ...16][15... CPUID feature bit ...0] * * but since this is all hidden in the macros argument being split, those fields can be * extended in the future to fit in a u64 or however the need arises. */ struct alt_instr { s32 instr_offset; /* original instruction */ s32 repl_offset; /* offset to replacement instruction */ union { struct { u32 cpuid: 16; /* CPUID bit set for replacement */ u32 flags: 16; /* patching control flags */ }; u32 ft_flags; }; u8 instrlen; /* length of original instruction */ u8 replacementlen; /* length of new instruction */ } __packed; extern struct alt_instr __alt_instructions[], __alt_instructions_end[]; /* * Debug flag that can be tested to see whether alternative * instructions were patched in already: */ extern int alternatives_patched; extern void alternative_instructions(void); extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end); extern void apply_retpolines(s32 *start, s32 *end); extern void apply_returns(s32 *start, s32 *end); extern void apply_seal_endbr(s32 *start, s32 *end); extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine, s32 *start_cfi, s32 *end_cfi); struct module; struct callthunk_sites { s32 *call_start, *call_end; struct alt_instr *alt_start, *alt_end; }; #ifdef CONFIG_CALL_THUNKS extern void callthunks_patch_builtin_calls(void); extern void callthunks_patch_module_calls(struct callthunk_sites *sites, struct module *mod); extern void *callthunks_translate_call_dest(void *dest); extern int x86_call_depth_emit_accounting(u8 **pprog, void *func, void *ip); #else static __always_inline void callthunks_patch_builtin_calls(void) {} static __always_inline void callthunks_patch_module_calls(struct callthunk_sites *sites, struct module *mod) {} static __always_inline void *callthunks_translate_call_dest(void *dest) { return dest; } static __always_inline int x86_call_depth_emit_accounting(u8 **pprog, void *func, void *ip) { return 0; } #endif #ifdef CONFIG_SMP extern void alternatives_smp_module_add(struct module *mod, char *name, void *locks, void *locks_end, void *text, void *text_end); extern void alternatives_smp_module_del(struct module *mod); extern void alternatives_enable_smp(void); extern int alternatives_text_reserved(void *start, void *end); extern bool skip_smp_alternatives; #else static inline void alternatives_smp_module_add(struct module *mod, char *name, void *locks, void *locks_end, void *text, void *text_end) {} static inline void alternatives_smp_module_del(struct module *mod) {} static inline void alternatives_enable_smp(void) {} static inline int alternatives_text_reserved(void *start, void *end) { return 0; } #endif /* CONFIG_SMP */ #define ALT_CALL_INSTR … #define alt_slen … #define alt_total_slen … #define alt_rlen … #define OLDINSTR … #define ALTINSTR_ENTRY … #define ALTINSTR_REPLACEMENT … /* alternative assembly primitive: */ #define ALTERNATIVE … #define ALTERNATIVE_2 … /* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ #define ALTERNATIVE_TERNARY … #define ALTERNATIVE_3 … /* * 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 … #define alternative_2 … /* * Alternative inline assembly with input. * * Peculiarities: * No memory clobber here. * Argument numbers start with 1. * Leaving an unused argument 0 to keep API compatibility. */ #define alternative_input … /* Like alternative_input, but with a single output argument */ #define alternative_io … /* * Like alternative_io, but for replacing a direct call with another one. * * Use the %c operand modifier which is the generic way to print a bare * constant expression with all syntax-specific punctuation omitted. %P * is the x86-specific variant which can handle constants too, for * historical reasons, but it should be used primarily for PIC * references: i.e., if used for a function, it would add the PLT * suffix. */ #define alternative_call … /* * Like alternative_call, but there are two features and respective functions. * If CPU has feature2, function2 is used. * Otherwise, if CPU has feature1, function1 is used. * Otherwise, old function is used. */ #define alternative_call_2 … /* * use this macro(s) if you need more than one output parameter * in alternative_io */ #define ASM_OUTPUT2 … /* * use this macro if you need clobbers but no inputs in * alternative_{input,io,call}() */ #define ASM_NO_INPUT_CLOBBER … #define ALT_OUTPUT_SP … /* Macro for creating assembler functions avoiding any C magic. */ #define DEFINE_ASM_FUNC … void BUG_func(void); void nop_func(void); #else /* __ASSEMBLY__ */ #ifdef CONFIG_SMP .macro LOCK_PREFIX 672: lock .pushsection .smp_locks,"a" .balign 4 .long 672b - . .popsection .endm #else .macro LOCK_PREFIX .endm #endif /* * objtool annotation to ignore the alternatives and only consider the original * instruction(s). */ .macro ANNOTATE_IGNORE_ALTERNATIVE .Lannotate_\@: .pushsection .discard.ignore_alts .long .Lannotate_\@ .popsection .endm /* * Issue one struct alt_instr descriptor entry (need to put it into * the section .altinstructions, see below). This entry contains * enough information for the alternatives patching code to patch an * instruction. See apply_alternatives(). */ .macro altinstr_entry orig alt ft_flags orig_len alt_len .long \orig - . .long \alt - . .4byte \ft_flags .byte \orig_len .byte \alt_len .endm .macro ALT_CALL_INSTR call BUG_func .endm /* * Define an alternative between two instructions. If @feature is * present, early code in apply_alternatives() replaces @oldinstr with * @newinstr. ".skip" directive takes care of proper instruction padding * in case @newinstr is longer than @oldinstr. */ #define __ALTERNATIVE(oldinst, newinst, flag) … .macro ALTERNATIVE oldinstr, newinstr, ft_flags __ALTERNATIVE(…) .endm #define old_len … #define new_len1 … #define new_len2 … #define new_len3 … /* * Same as ALTERNATIVE macro above but for two alternatives. If CPU * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has * @feature2, it replaces @oldinstr with @feature2. */ .macro ALTERNATIVE_2 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2 __ALTERNATIVE(…) .endm .macro ALTERNATIVE_3 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, newinstr3, ft_flags3 __ALTERNATIVE(…) .endm /* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ #define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) … #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_ALTERNATIVE_H */
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