/usr/src/kernels/4.18.0-553.157.1.el8_10.x86_64/arch/x86/include/asm
Edit: /usr/src/kernels/4.18.0-553.157.1.el8_10.x86_64/arch/x86/include/asm/alternative.h (11407B)
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_ALTERNATIVE_H
#define _ASM_X86_ALTERNATIVE_H
#include
#include
#include
#define ALTINSTR_FLAG_INV (1 << 15)
#define ALT_NOT(feat) ((feat) | ALTINSTR_FLAG_INV)
#ifndef __ASSEMBLY__
#include
/*
* 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 \
".pushsection .smp_locks,\"a\"\n" \
".balign 4\n" \
".long 671f - .\n" /* offset */ \
".popsection\n" \
"671:"
#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "
#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 \
"999:\n\t" \
".pushsection .discard.ignore_alts\n\t" \
".long 999b - .\n\t" \
".popsection\n\t"
struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
u16 cpuid; /* cpuid bit set for replacement */
u8 instrlen; /* length of original instruction */
u8 replacementlen; /* length of new instruction */
u8 padlen; /* length of build-time padding */
} __packed;
/*
* 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_returns(s32 *start, s32 *end);
struct module;
#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 b_replacement(num) "664"#num
#define e_replacement(num) "665"#num
#define alt_end_marker "663"
#define alt_slen "662b-661b"
#define alt_pad_len alt_end_marker"b-662b"
#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" \
".skip -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \
"((" alt_rlen(num) ")-(" alt_slen ")),0x90\n"
#define OLDINSTR(oldinstr, num) \
__OLDINSTR(oldinstr, num) \
alt_end_marker ":\n"
/*
* gas compatible max based on the idea from:
* http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
*
* The additional "-" is needed because gas uses a "true" value of -1.
*/
#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" \
".skip -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \
"(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")), 0x90\n" \
alt_end_marker ":\n"
#define ALTINSTR_ENTRY(feature, num) \
" .long 661b - .\n" /* label */ \
" .long " b_replacement(num)"f - .\n" /* new instruction */ \
" .word " __stringify(feature) "\n" /* feature bit */ \
" .byte " alt_total_slen "\n" /* source len */ \
" .byte " alt_rlen(num) "\n" /* replacement len */ \
" .byte " alt_pad_len "\n" /* pad 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" \
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(newinstr, feature, 1) \
".popsection\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" \
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \
ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
".popsection\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")
/*
* Alternative inline assembly with input.
*
* Peculiarities:
* No memory clobber here.
* Argument numbers start with 1.
* Best is to use constraints that are fixed size (like (%1) ... "r")
* If you use variable sized constraints like "m" or "g" in the
* replacement make sure to pad to the worst case length.
* Leaving an unused argument 0 to keep API compatibility.
*/
#define alternative_input(oldinstr, newinstr, feature, input...) \
asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
: : "i" (0), ## input)
/*
* This is similar to alternative_input. But it has two features and
* respective instructions.
*
* If CPU has feature2, newinstr2 is used.
* Otherwise, if CPU has feature1, newinstr1 is used.
* Otherwise, oldinstr is used.
*/
#define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2, \
feature2, input...) \
asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
newinstr2, feature2) \
: : "i" (0), ## input)
/* Like alternative_input, but with a single output argument */
#define alternative_io(oldinstr, newinstr, feature, output, input...) \
asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
: output : "i" (0), ## input)
/* Like alternative_io, but for replacing a direct call with another one. */
#define alternative_call(oldfunc, newfunc, feature, output, input...) \
asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
/*
* 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(oldfunc, newfunc1, feature1, newfunc2, feature2, \
output, input...) \
asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
"call %P[new2]", feature2) \
: output, ASM_CALL_CONSTRAINT \
: [old] "i" (oldfunc), [new1] "i" (newfunc1), \
[new2] "i" (newfunc2), ## input)
/*
* use this macro(s) if you need more than one output parameter
* in alternative_io
*/
#define ASM_OUTPUT2(a...) a
/*
* use this macro if you need clobbers but no inputs in
* alternative_{input,io,call}()
*/
#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr
#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 altinstruction_entry orig alt feature orig_len alt_len pad_len
.long \orig - .
.long \alt - .
.word \feature
.byte \orig_len
.byte \alt_len
.byte \pad_len
.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.
*/
.macro ALTERNATIVE oldinstr, newinstr, feature
140:
\oldinstr
141:
.skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
142:
.pushsection .altinstructions,"a"
altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b
.popsection
.pushsection .altinstr_replacement,"ax"
143:
\newinstr
144:
.popsection
.endm
#define old_len 141b-140b
#define new_len1 144f-143f
#define new_len2 145f-144f
/*
* gas compatible max based on the idea from:
* http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax
*
* The additional "-" is needed because gas uses a "true" value of -1.
*/
#define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
/*
* 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, feature1, newinstr2, feature2
140:
\oldinstr
141:
.skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
(alt_max_short(new_len1, new_len2) - (old_len)),0x90
142:
.pushsection .altinstructions,"a"
altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b
altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b
.popsection
.pushsection .altinstr_replacement,"ax"
143:
\newinstr1
144:
\newinstr2
145:
.popsection
.endm
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_ALTERNATIVE_H */