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- This is basically PeterZ's idea to nest the alternative macros to avoid the
need to "spell out" the number of alternates in an ALTERNATIVE_n() macro and thus have an ever-increasing complexity in those definitions. For ease of bisection, the old macros are converted to the new, nested variants in a step-by-step manner so that in case an issue is encountered during testing, one can pinpoint the place where it fails easier. Because debugging alternatives is a serious pain. -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmaU/+MACgkQEsHwGGHe VUpMGhAAqVbB3DZohv0Oa4BRRvaKFuQ3L7H0NTjK/pbT3EG+phol0zrHby2MnGjD HWXskps86n91QBB/06vAyZRimV/dvAPvlSKllsRx6ie3VCE4FJPzA4nTWQn/41dC HWamj78mQuSMgioLzIYdTY79KObtJcUw/X/xz+TTMemfkzkQxukKY7+Y71nZbuKi rUuCSrfAWNHQaIaoGs2JowGw7te7yNOtKQMCW5TdNLwvJfOAECuoLIFeiEcWHvoO uGl6FTABNLp26wmaeceUxdjBbTJcM3iV3joZQYED7B+mbJcU/a7tZw7I+mavPrbh Y6+EOn7rzR0wbcmj0iJ74TKr+uKDme/Qzm3YEKgGvJPj9tRjTDwxWRBnyTeCMbav NkKVwWTep8K+1qJtGVBwACY6iz89u3P8V5owD8O++KIPQa8rA0m8pN5gaU3PVYYQ D2UUdqXWIPIFoD4Sveb/WFU8OJKY+Nx7IK8KD03h5tiXW8MmGSa2e5b57gIfCLP7 DbSHyCkTiqEdBrSM4/RaVVckD6NZ39M87H+iV51vYUkCYmODa/riMj0M7SVMi5Jo S/30jvdHEzWnmDBbOsn9d1XbvB5I+zz3BrcZQ2VSyBx+Y9m+SZ9qsyMEkOWw4uKM kfFp+XlYVWSnQFo7jY3UUIgVrU9dmdX1WxNX7/2HABDjg3MtWog= =tGap -----END PGP SIGNATURE----- Merge tag 'x86_alternatives_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 alternatives updates from Borislav Petkov: "This is basically PeterZ's idea to nest the alternative macros to avoid the need to "spell out" the number of alternates in an ALTERNATIVE_n() macro and thus have an ever-increasing complexity in those definitions. For ease of bisection, the old macros are converted to the new, nested variants in a step-by-step manner so that in case an issue is encountered during testing, one can pinpoint the place where it fails easier. Because debugging alternatives is a serious pain" * tag 'x86_alternatives_for_v6.11_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/alternatives, kvm: Fix a couple of CALLs without a frame pointer x86/alternative: Replace the old macros x86/alternative: Convert the asm ALTERNATIVE_3() macro x86/alternative: Convert the asm ALTERNATIVE_2() macro x86/alternative: Convert the asm ALTERNATIVE() macro x86/alternative: Convert ALTERNATIVE_3() x86/alternative: Convert ALTERNATIVE_TERNARY() x86/alternative: Convert alternative_call_2() x86/alternative: Convert alternative_call() x86/alternative: Convert alternative_io() x86/alternative: Convert alternative_input() x86/alternative: Convert alternative_2() x86/alternative: Convert alternative() x86/alternatives: Add nested alternatives macros x86/alternative: Zap alternative_ternary()
This commit is contained in:
Linus Torvalds
commit
208c6772d3
@ -156,102 +156,50 @@ static inline int alternatives_text_reserved(void *start, void *end)
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#define ALT_CALL_INSTR "call BUG_func"
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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_slen "772b-771b"
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#define alt_total_slen "773b-771b"
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#define alt_rlen "775f-774f"
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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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#define OLDINSTR(oldinstr) \
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"# ALT: oldinstr\n" \
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"771:\n\t" oldinstr "\n772:\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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".skip -(((" alt_rlen ")-(" alt_slen ")) > 0) * " \
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"((" alt_rlen ")-(" alt_slen ")),0x90\n" \
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"773:\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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#define ALTINSTR_ENTRY(ft_flags) \
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".pushsection .altinstructions,\"a\"\n" \
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" .long 771b - .\n" /* label */ \
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" .long 774f - .\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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" .byte " alt_rlen "\n" /* replacement len */ \
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".popsection\n"
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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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#define ALTINSTR_REPLACEMENT(newinstr) /* replacement */ \
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".pushsection .altinstr_replacement, \"ax\"\n" \
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"# ALT: replacement\n" \
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"774:\n\t" newinstr "\n775:\n" \
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".popsection\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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OLDINSTR(oldinstr) \
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ALTINSTR_ENTRY(ft_flags) \
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ALTINSTR_REPLACEMENT(newinstr)
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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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ALTERNATIVE(ALTERNATIVE(oldinstr, newinstr1, ft_flags1), newinstr2, ft_flags2)
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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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ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, 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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#define ALTERNATIVE_3(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, \
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newinstr3, ft_flags3) \
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ALTERNATIVE(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2), \
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newinstr3, ft_flags3)
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/*
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* Alternative instructions for different CPU types or capabilities.
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@ -266,14 +214,11 @@ static inline int alternatives_text_reserved(void *start, void *end)
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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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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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@ -283,18 +228,28 @@ static inline int alternatives_text_reserved(void *start, void *end)
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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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asm_inline volatile(ALTERNATIVE(oldinstr, newinstr, ft_flags) \
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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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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 %c[old]", "call %c[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_io, but for replacing a direct call with another one.
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*
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* Use the %c operand modifier which is the generic way to print a bare
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* constant expression with all syntax-specific punctuation omitted. %P
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* is the x86-specific variant which can handle constants too, for
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* historical reasons, but it should be used primarily for PIC
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* references: i.e., if used for a function, it would add the PLT
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* suffix.
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*/
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#define alternative_call(oldfunc, newfunc, ft_flags, output, input...) \
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asm_inline volatile(ALTERNATIVE("call %c[old]", "call %c[new]", ft_flags) \
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: ALT_OUTPUT_SP(output) \
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: [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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@ -302,12 +257,12 @@ static inline int alternatives_text_reserved(void *start, void *end)
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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 %c[old]", "call %c[new1]", ft_flags1, \
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"call %c[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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#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 %c[old]", "call %c[new1]", ft_flags1, \
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"call %c[new2]", ft_flags2) \
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: ALT_OUTPUT_SP(output) \
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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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@ -322,6 +277,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
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*/
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#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr
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#define ALT_OUTPUT_SP(...) ASM_CALL_CONSTRAINT, ## __VA_ARGS__
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/* Macro for creating assembler functions avoiding any C magic. */
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#define DEFINE_ASM_FUNC(func, instr, sec) \
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asm (".pushsection " #sec ", \"ax\"\n" \
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@ -388,22 +345,23 @@ void nop_func(void);
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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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#define __ALTERNATIVE(oldinst, newinst, flag) \
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740: \
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oldinst ; \
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741: \
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.skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\
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742: \
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.pushsection .altinstructions,"a" ; \
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altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \
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.popsection ; \
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.pushsection .altinstr_replacement,"ax" ; \
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743: \
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newinst ; \
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744: \
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.popsection ;
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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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__ALTERNATIVE(\oldinstr, \newinstr, \ft_flags)
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.endm
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#define old_len 141b-140b
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@ -411,66 +369,19 @@ void nop_func(void);
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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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__ALTERNATIVE(__ALTERNATIVE(\oldinstr, \newinstr1, \ft_flags1),
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\newinstr2, \ft_flags2)
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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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__ALTERNATIVE(ALTERNATIVE_2(\oldinstr, \newinstr1, \ft_flags1, \newinstr2, \ft_flags2),
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\newinstr3, \ft_flags3)
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.endm
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/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */
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@ -54,7 +54,7 @@ static inline void clear_page(void *page)
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clear_page_rep, X86_FEATURE_REP_GOOD,
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clear_page_erms, X86_FEATURE_ERMS,
|
||||
"=D" (page),
|
||||
"0" (page)
|
||||
"D" (page)
|
||||
: "cc", "memory", "rax", "rcx");
|
||||
}
|
||||
|
||||
|
||||
@ -432,6 +432,11 @@ static int alt_replace_call(u8 *instr, u8 *insn_buff, struct alt_instr *a)
|
||||
return 5;
|
||||
}
|
||||
|
||||
static inline u8 * instr_va(struct alt_instr *i)
|
||||
{
|
||||
return (u8 *)&i->instr_offset + i->instr_offset;
|
||||
}
|
||||
|
||||
/*
|
||||
* Replace instructions with better alternatives for this CPU type. This runs
|
||||
* before SMP is initialized to avoid SMP problems with self modifying code.
|
||||
@ -447,7 +452,7 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
|
||||
{
|
||||
u8 insn_buff[MAX_PATCH_LEN];
|
||||
u8 *instr, *replacement;
|
||||
struct alt_instr *a;
|
||||
struct alt_instr *a, *b;
|
||||
|
||||
DPRINTK(ALT, "alt table %px, -> %px", start, end);
|
||||
|
||||
@ -473,7 +478,18 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
|
||||
for (a = start; a < end; a++) {
|
||||
int insn_buff_sz = 0;
|
||||
|
||||
instr = (u8 *)&a->instr_offset + a->instr_offset;
|
||||
/*
|
||||
* In case of nested ALTERNATIVE()s the outer alternative might
|
||||
* add more padding. To ensure consistent patching find the max
|
||||
* padding for all alt_instr entries for this site (nested
|
||||
* alternatives result in consecutive entries).
|
||||
*/
|
||||
for (b = a+1; b < end && instr_va(b) == instr_va(a); b++) {
|
||||
u8 len = max(a->instrlen, b->instrlen);
|
||||
a->instrlen = b->instrlen = len;
|
||||
}
|
||||
|
||||
instr = instr_va(a);
|
||||
replacement = (u8 *)&a->repl_offset + a->repl_offset;
|
||||
BUG_ON(a->instrlen > sizeof(insn_buff));
|
||||
BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32);
|
||||
@ -1641,7 +1657,7 @@ static noinline void __init alt_reloc_selftest(void)
|
||||
*/
|
||||
asm_inline volatile (
|
||||
ALTERNATIVE("", "lea %[mem], %%" _ASM_ARG1 "; call __alt_reloc_selftest;", X86_FEATURE_ALWAYS)
|
||||
: /* output */
|
||||
: ASM_CALL_CONSTRAINT
|
||||
: [mem] "m" (__alt_reloc_selftest_addr)
|
||||
: _ASM_ARG1
|
||||
);
|
||||
|
||||
@ -106,21 +106,17 @@ static inline u64 xfeatures_mask_independent(void)
|
||||
* Otherwise, if XSAVEOPT is enabled, XSAVEOPT replaces XSAVE because XSAVEOPT
|
||||
* supports modified optimization which is not supported by XSAVE.
|
||||
*
|
||||
* We use XSAVE as a fallback.
|
||||
*
|
||||
* The 661 label is defined in the ALTERNATIVE* macros as the address of the
|
||||
* original instruction which gets replaced. We need to use it here as the
|
||||
* address of the instruction where we might get an exception at.
|
||||
* Use XSAVE as a fallback.
|
||||
*/
|
||||
#define XSTATE_XSAVE(st, lmask, hmask, err) \
|
||||
asm volatile(ALTERNATIVE_3(XSAVE, \
|
||||
asm volatile("1: " ALTERNATIVE_3(XSAVE, \
|
||||
XSAVEOPT, X86_FEATURE_XSAVEOPT, \
|
||||
XSAVEC, X86_FEATURE_XSAVEC, \
|
||||
XSAVES, X86_FEATURE_XSAVES) \
|
||||
"\n" \
|
||||
"xor %[err], %[err]\n" \
|
||||
"3:\n" \
|
||||
_ASM_EXTABLE_TYPE_REG(661b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
|
||||
_ASM_EXTABLE_TYPE_REG(1b, 3b, EX_TYPE_EFAULT_REG, %[err]) \
|
||||
: [err] "=r" (err) \
|
||||
: "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
|
||||
: "memory")
|
||||
@ -130,11 +126,11 @@ static inline u64 xfeatures_mask_independent(void)
|
||||
* XSAVE area format.
|
||||
*/
|
||||
#define XSTATE_XRESTORE(st, lmask, hmask) \
|
||||
asm volatile(ALTERNATIVE(XRSTOR, \
|
||||
asm volatile("1: " ALTERNATIVE(XRSTOR, \
|
||||
XRSTORS, X86_FEATURE_XSAVES) \
|
||||
"\n" \
|
||||
"3:\n" \
|
||||
_ASM_EXTABLE_TYPE(661b, 3b, EX_TYPE_FPU_RESTORE) \
|
||||
_ASM_EXTABLE_TYPE(1b, 3b, EX_TYPE_FPU_RESTORE) \
|
||||
: \
|
||||
: "D" (st), "m" (*st), "a" (lmask), "d" (hmask) \
|
||||
: "memory")
|
||||
|
||||
@ -1069,7 +1069,7 @@ static __always_inline u8 test_cc(unsigned int condition, unsigned long flags)
|
||||
|
||||
flags = (flags & EFLAGS_MASK) | X86_EFLAGS_IF;
|
||||
asm("push %[flags]; popf; " CALL_NOSPEC
|
||||
: "=a"(rc) : [thunk_target]"r"(fop), [flags]"r"(flags));
|
||||
: "=a"(rc), ASM_CALL_CONSTRAINT : [thunk_target]"r"(fop), [flags]"r"(flags));
|
||||
return rc;
|
||||
}
|
||||
|
||||
|
||||
@ -284,6 +284,25 @@ the objtool maintainers.
|
||||
|
||||
Otherwise the stack frame may not get created before the call.
|
||||
|
||||
objtool can help with pinpointing the exact function where it happens:
|
||||
|
||||
$ OBJTOOL_ARGS="--verbose" make arch/x86/kvm/
|
||||
|
||||
arch/x86/kvm/kvm.o: warning: objtool: .altinstr_replacement+0xc5: call without frame pointer save/setup
|
||||
arch/x86/kvm/kvm.o: warning: objtool: em_loop.part.0+0x29: (alt)
|
||||
arch/x86/kvm/kvm.o: warning: objtool: em_loop.part.0+0x0: <=== (sym)
|
||||
LD [M] arch/x86/kvm/kvm-intel.o
|
||||
0000 0000000000028220 <em_loop.part.0>:
|
||||
0000 28220: 0f b6 47 61 movzbl 0x61(%rdi),%eax
|
||||
0004 28224: 3c e2 cmp $0xe2,%al
|
||||
0006 28226: 74 2c je 28254 <em_loop.part.0+0x34>
|
||||
0008 28228: 48 8b 57 10 mov 0x10(%rdi),%rdx
|
||||
000c 2822c: 83 f0 05 xor $0x5,%eax
|
||||
000f 2822f: 48 c1 e0 04 shl $0x4,%rax
|
||||
0013 28233: 25 f0 00 00 00 and $0xf0,%eax
|
||||
0018 28238: 81 e2 d5 08 00 00 and $0x8d5,%edx
|
||||
001e 2823e: 80 ce 02 or $0x2,%dh
|
||||
...
|
||||
|
||||
2. file.o: warning: objtool: .text+0x53: unreachable instruction
|
||||
|
||||
|
||||
@ -9,6 +9,29 @@
|
||||
|
||||
void arch_handle_alternative(unsigned short feature, struct special_alt *alt)
|
||||
{
|
||||
static struct special_alt *group, *prev;
|
||||
|
||||
/*
|
||||
* Recompute orig_len for nested ALTERNATIVE()s.
|
||||
*/
|
||||
if (group && group->orig_sec == alt->orig_sec &&
|
||||
group->orig_off == alt->orig_off) {
|
||||
|
||||
struct special_alt *iter = group;
|
||||
for (;;) {
|
||||
unsigned int len = max(iter->orig_len, alt->orig_len);
|
||||
iter->orig_len = alt->orig_len = len;
|
||||
|
||||
if (iter == prev)
|
||||
break;
|
||||
|
||||
iter = list_next_entry(iter, list);
|
||||
}
|
||||
|
||||
} else group = alt;
|
||||
|
||||
prev = alt;
|
||||
|
||||
switch (feature) {
|
||||
case X86_FEATURE_SMAP:
|
||||
/*
|
||||
|
||||
@ -84,6 +84,14 @@ static int get_alt_entry(struct elf *elf, const struct special_entry *entry,
|
||||
entry->new_len);
|
||||
}
|
||||
|
||||
orig_reloc = find_reloc_by_dest(elf, sec, offset + entry->orig);
|
||||
if (!orig_reloc) {
|
||||
WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
|
||||
return -1;
|
||||
}
|
||||
|
||||
reloc_to_sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off);
|
||||
|
||||
if (entry->feature) {
|
||||
unsigned short feature;
|
||||
|
||||
@ -94,14 +102,6 @@ static int get_alt_entry(struct elf *elf, const struct special_entry *entry,
|
||||
arch_handle_alternative(feature, alt);
|
||||
}
|
||||
|
||||
orig_reloc = find_reloc_by_dest(elf, sec, offset + entry->orig);
|
||||
if (!orig_reloc) {
|
||||
WARN_FUNC("can't find orig reloc", sec, offset + entry->orig);
|
||||
return -1;
|
||||
}
|
||||
|
||||
reloc_to_sec_off(orig_reloc, &alt->orig_sec, &alt->orig_off);
|
||||
|
||||
if (!entry->group || alt->new_len) {
|
||||
new_reloc = find_reloc_by_dest(elf, sec, offset + entry->new);
|
||||
if (!new_reloc) {
|
||||
|
||||
Loading…
Reference in New Issue
Block a user