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#ifndef __X86_ALTERNATIVE_H__
#define __X86_ALTERNATIVE_H__
#ifdef __ASSEMBLY__
#include <asm/alternative-asm.h>
#else
#include <xen/lib.h>
#include <xen/stringify.h>
#include <asm/asm-macros.h>
struct __packed alt_instr {
int32_t orig_offset; /* original instruction */
int32_t repl_offset; /* offset to replacement instruction */
uint16_t cpuid; /* cpuid bit set for replacement */
uint8_t orig_len; /* length of original instruction */
uint8_t repl_len; /* length of new instruction */
uint8_t pad_len; /* length of build-time padding */
uint8_t priv; /* Private, for use by apply_alternatives() */
};
#define __ALT_PTR(a,f) ((uint8_t *)((void *)&(a)->f + (a)->f))
#define ALT_ORIG_PTR(a) __ALT_PTR(a, orig_offset)
#define ALT_REPL_PTR(a) __ALT_PTR(a, repl_offset)
extern void add_nops(void *insns, unsigned int len);
/* Similar to alternative_instructions except it can be run with IRQs enabled. */
extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
extern void alternative_instructions(void);
extern void alternative_branches(void);
#define alt_orig_len "(.LXEN%=_orig_e - .LXEN%=_orig_s)"
#define alt_pad_len "(.LXEN%=_orig_p - .LXEN%=_orig_e)"
#define alt_total_len "(.LXEN%=_orig_p - .LXEN%=_orig_s)"
#define alt_repl_s(num) ".LXEN%=_repl_s"#num
#define alt_repl_e(num) ".LXEN%=_repl_e"#num
#define alt_repl_len(num) "(" alt_repl_e(num) " - " alt_repl_s(num) ")"
/* GAS's idea of true is -1, while Clang's idea is 1. */
#ifdef HAVE_AS_NEGATIVE_TRUE
# define AS_TRUE "-"
#else
# define AS_TRUE ""
#endif
#define as_max(a, b) "(("a") ^ ((("a") ^ ("b")) & -("AS_TRUE"(("a") < ("b")))))"
#define OLDINSTR(oldinstr, padding) \
".LXEN%=_orig_s:\n\t" oldinstr "\n .LXEN%=_orig_e:\n\t" \
".LXEN%=_diff = " padding "\n\t" \
"mknops ("AS_TRUE"(.LXEN%=_diff > 0) * .LXEN%=_diff)\n\t" \
".LXEN%=_orig_p:\n\t"
#define OLDINSTR_1(oldinstr, n1) \
OLDINSTR(oldinstr, alt_repl_len(n1) "-" alt_orig_len)
#define OLDINSTR_2(oldinstr, n1, n2) \
OLDINSTR(oldinstr, \
as_max(alt_repl_len(n1), \
alt_repl_len(n2)) "-" alt_orig_len)
#define ALTINSTR_ENTRY(feature, num) \
" .long .LXEN%=_orig_s - .\n" /* label */ \
" .long " alt_repl_s(num)" - .\n" /* new instruction */ \
" .word " __stringify(feature) "\n" /* feature bit */ \
" .byte " alt_orig_len "\n" /* source len */ \
" .byte " alt_repl_len(num) "\n" /* replacement len */ \
" .byte " alt_pad_len "\n" /* padding len */ \
" .byte 0\n" /* priv */
#define DISCARD_ENTRY(num) /* repl <= total */ \
" .byte 0xff + (" alt_repl_len(num) ") - (" alt_total_len ")\n"
#define ALTINSTR_REPLACEMENT(newinstr, num) /* replacement */ \
alt_repl_s(num)":\n\t" newinstr "\n" alt_repl_e(num) ":\n\t"
/* alternative assembly primitive: */
#define ALTERNATIVE(oldinstr, newinstr, feature) \
OLDINSTR_1(oldinstr, 1) \
".pushsection .altinstructions, \"a\", @progbits\n" \
ALTINSTR_ENTRY(feature, 1) \
".section .discard, \"a\", @progbits\n" \
".byte " alt_total_len "\n" /* total_len <= 255 */ \
DISCARD_ENTRY(1) \
".section .altinstr_replacement, \"ax\", @progbits\n" \
ALTINSTR_REPLACEMENT(newinstr, 1) \
".popsection\n"
#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
OLDINSTR_2(oldinstr, 1, 2) \
".pushsection .altinstructions, \"a\", @progbits\n" \
ALTINSTR_ENTRY(feature1, 1) \
ALTINSTR_ENTRY(feature2, 2) \
".section .discard, \"a\", @progbits\n" \
".byte " alt_total_len "\n" /* total_len <= 255 */ \
DISCARD_ENTRY(1) \
DISCARD_ENTRY(2) \
".section .altinstr_replacement, \"ax\", @progbits\n" \
ALTINSTR_REPLACEMENT(newinstr1, 1) \
ALTINSTR_REPLACEMENT(newinstr2, 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.
*
* Pecularities:
* 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.
*/
#define alternative_input(oldinstr, newinstr, feature, input...) \
asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
: : 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 : input)
/*
* This is similar to alternative_io. 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_io_2(oldinstr, newinstr1, feature1, newinstr2, \
feature2, output, input...) \
asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
newinstr2, feature2) \
: output : input)
/* Use this macro(s) if you need more than one output parameter. */
#define ASM_OUTPUT2(a...) a
/*
* Machinery to allow converting indirect to direct calls, when the called
* function is determined once at boot and later never changed.
*/
#define ALT_CALL_arg1 "rdi"
#define ALT_CALL_arg2 "rsi"
#define ALT_CALL_arg3 "rdx"
#define ALT_CALL_arg4 "rcx"
#define ALT_CALL_arg5 "r8"
#define ALT_CALL_arg6 "r9"
#define ALT_CALL_ARG(arg, n) \
register typeof((arg) ? (arg) : 0) a ## n ## _ \
asm ( ALT_CALL_arg ## n ) = (arg)
#define ALT_CALL_NO_ARG(n) \
register unsigned long a ## n ## _ asm ( ALT_CALL_arg ## n )
#define ALT_CALL_NO_ARG6 ALT_CALL_NO_ARG(6)
#define ALT_CALL_NO_ARG5 ALT_CALL_NO_ARG(5); ALT_CALL_NO_ARG6
#define ALT_CALL_NO_ARG4 ALT_CALL_NO_ARG(4); ALT_CALL_NO_ARG5
#define ALT_CALL_NO_ARG3 ALT_CALL_NO_ARG(3); ALT_CALL_NO_ARG4
#define ALT_CALL_NO_ARG2 ALT_CALL_NO_ARG(2); ALT_CALL_NO_ARG3
#define ALT_CALL_NO_ARG1 ALT_CALL_NO_ARG(1); ALT_CALL_NO_ARG2
/*
* Unfortunately ALT_CALL_NO_ARG() above can't use a fake initializer (to
* suppress "uninitialized variable" warnings), as various versions of gcc
* older than 8.1 fall on the nose in various ways with that (always because
* of some other construct elsewhere in the same function needing to use the
* same hard register). Otherwise the asm() below could uniformly use "+r"
* output constraints, making unnecessary all these ALT_CALL<n>_OUT macros.
*/
#define ALT_CALL0_OUT "=r" (a1_), "=r" (a2_), "=r" (a3_), \
"=r" (a4_), "=r" (a5_), "=r" (a6_)
#define ALT_CALL1_OUT "+r" (a1_), "=r" (a2_), "=r" (a3_), \
"=r" (a4_), "=r" (a5_), "=r" (a6_)
#define ALT_CALL2_OUT "+r" (a1_), "+r" (a2_), "=r" (a3_), \
"=r" (a4_), "=r" (a5_), "=r" (a6_)
#define ALT_CALL3_OUT "+r" (a1_), "+r" (a2_), "+r" (a3_), \
"=r" (a4_), "=r" (a5_), "=r" (a6_)
#define ALT_CALL4_OUT "+r" (a1_), "+r" (a2_), "+r" (a3_), \
"+r" (a4_), "=r" (a5_), "=r" (a6_)
#define ALT_CALL5_OUT "+r" (a1_), "+r" (a2_), "+r" (a3_), \
"+r" (a4_), "+r" (a5_), "=r" (a6_)
#define ALT_CALL6_OUT "+r" (a1_), "+r" (a2_), "+r" (a3_), \
"+r" (a4_), "+r" (a5_), "+r" (a6_)
#define alternative_callN(n, rettype, func) ({ \
rettype ret_; \
register unsigned long r10_ asm("r10"); \
register unsigned long r11_ asm("r11"); \
asm volatile (ALTERNATIVE("call *%c[addr](%%rip)", "call .", \
X86_FEATURE_ALWAYS) \
: ALT_CALL ## n ## _OUT, "=a" (ret_), \
"=r" (r10_), "=r" (r11_) ASM_CALL_CONSTRAINT \
: [addr] "i" (&(func)), "g" (func) \
: "memory" ); \
ret_; \
})
#define alternative_vcall0(func) ({ \
ALT_CALL_NO_ARG1; \
((void)alternative_callN(0, int, func)); \
})
#define alternative_call0(func) ({ \
ALT_CALL_NO_ARG1; \
alternative_callN(0, typeof(func()), func); \
})
#define alternative_vcall1(func, arg) ({ \
ALT_CALL_ARG(arg, 1); \
ALT_CALL_NO_ARG2; \
(void)sizeof(func(arg)); \
(void)alternative_callN(1, int, func); \
})
#define alternative_call1(func, arg) ({ \
ALT_CALL_ARG(arg, 1); \
ALT_CALL_NO_ARG2; \
alternative_callN(1, typeof(func(arg)), func); \
})
#define alternative_vcall2(func, arg1, arg2) ({ \
typeof(arg2) v2_ = (arg2); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_NO_ARG3; \
(void)sizeof(func(arg1, arg2)); \
(void)alternative_callN(2, int, func); \
})
#define alternative_call2(func, arg1, arg2) ({ \
typeof(arg2) v2_ = (arg2); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_NO_ARG3; \
alternative_callN(2, typeof(func(arg1, arg2)), func); \
})
#define alternative_vcall3(func, arg1, arg2, arg3) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_NO_ARG4; \
(void)sizeof(func(arg1, arg2, arg3)); \
(void)alternative_callN(3, int, func); \
})
#define alternative_call3(func, arg1, arg2, arg3) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_NO_ARG4; \
alternative_callN(3, typeof(func(arg1, arg2, arg3)), \
func); \
})
#define alternative_vcall4(func, arg1, arg2, arg3, arg4) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_NO_ARG5; \
(void)sizeof(func(arg1, arg2, arg3, arg4)); \
(void)alternative_callN(4, int, func); \
})
#define alternative_call4(func, arg1, arg2, arg3, arg4) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_NO_ARG5; \
alternative_callN(4, typeof(func(arg1, arg2, \
arg3, arg4)), \
func); \
})
#define alternative_vcall5(func, arg1, arg2, arg3, arg4, arg5) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
typeof(arg5) v5_ = (arg5); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_ARG(v5_, 5); \
ALT_CALL_NO_ARG6; \
(void)sizeof(func(arg1, arg2, arg3, arg4, arg5)); \
(void)alternative_callN(5, int, func); \
})
#define alternative_call5(func, arg1, arg2, arg3, arg4, arg5) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
typeof(arg5) v5_ = (arg5); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_ARG(v5_, 5); \
ALT_CALL_NO_ARG6; \
alternative_callN(5, typeof(func(arg1, arg2, arg3, \
arg4, arg5)), \
func); \
})
#define alternative_vcall6(func, arg1, arg2, arg3, arg4, arg5, arg6) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
typeof(arg5) v5_ = (arg5); \
typeof(arg6) v6_ = (arg6); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_ARG(v5_, 5); \
ALT_CALL_ARG(v6_, 6); \
(void)sizeof(func(arg1, arg2, arg3, arg4, arg5, arg6)); \
(void)alternative_callN(6, int, func); \
})
#define alternative_call6(func, arg1, arg2, arg3, arg4, arg5, arg6) ({ \
typeof(arg2) v2_ = (arg2); \
typeof(arg3) v3_ = (arg3); \
typeof(arg4) v4_ = (arg4); \
typeof(arg5) v5_ = (arg5); \
typeof(arg6) v6_ = (arg6); \
ALT_CALL_ARG(arg1, 1); \
ALT_CALL_ARG(v2_, 2); \
ALT_CALL_ARG(v3_, 3); \
ALT_CALL_ARG(v4_, 4); \
ALT_CALL_ARG(v5_, 5); \
ALT_CALL_ARG(v6_, 6); \
alternative_callN(6, typeof(func(arg1, arg2, arg3, \
arg4, arg5, arg6)), \
func); \
})
#define alternative_vcall__(nr) alternative_vcall ## nr
#define alternative_call__(nr) alternative_call ## nr
#define alternative_vcall_(nr) alternative_vcall__(nr)
#define alternative_call_(nr) alternative_call__(nr)
#define alternative_vcall(func, args...) \
alternative_vcall_(count_args(args))(func, ## args)
#define alternative_call(func, args...) \
alternative_call_(count_args(args))(func, ## args)
#endif /* !__ASSEMBLY__ */
#endif /* __X86_ALTERNATIVE_H__ */
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