diff options
| -rw-r--r-- | arch/x86/include/asm/alternative.h | 120 | ||||
| -rw-r--r-- | arch/x86/kernel/alternative.c | 20 | ||||
| -rw-r--r-- | tools/objtool/arch/x86/special.c | 23 | ||||
| -rw-r--r-- | tools/objtool/special.c | 16 |
4 files changed, 167 insertions, 12 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 6db78909180a..7d9ebc516bde 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -161,8 +161,13 @@ static inline int alternatives_text_reserved(void *start, void *end) #define alt_end_marker "663" #define alt_slen "662b-661b" +#define n_alt_slen "772b-771b" + #define alt_total_slen alt_end_marker"b-661b" +#define n_alt_total_slen "773b-771b" + #define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f" +#define n_alt_rlen "775f-774f" #define OLDINSTR(oldinstr, num) \ "# ALT: oldnstr\n" \ @@ -172,6 +177,14 @@ static inline int alternatives_text_reserved(void *start, void *end) "((" alt_rlen(num) ")-(" alt_slen ")),0x90\n" \ alt_end_marker ":\n" +#define N_OLDINSTR(oldinstr) \ + "# N_ALT: oldinstr\n" \ + "771:\n\t" oldinstr "\n772:\n" \ + "# N_ALT: padding\n" \ + ".skip -(((" n_alt_rlen ")-(" n_alt_slen ")) > 0) * " \ + "((" n_alt_rlen ")-(" n_alt_slen ")),0x90\n" \ + "773:\n" + /* * gas compatible max based on the idea from: * http://graphics.stanford.edu/~seander/bithacks.html#IntegerMinOrMax @@ -209,10 +222,25 @@ static inline int alternatives_text_reserved(void *start, void *end) " .byte " alt_total_slen "\n" /* source len */ \ " .byte " alt_rlen(num) "\n" /* replacement len */ +#define N_ALTINSTR_ENTRY(ft_flags) \ + ".pushsection .altinstructions,\"a\"\n" \ + " .long 771b - .\n" /* label */ \ + " .long 774f - .\n" /* new instruction */ \ + " .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \ + " .byte " n_alt_total_slen "\n" /* source len */ \ + " .byte " n_alt_rlen "\n" /* replacement len */ \ + ".popsection\n" + #define ALTINSTR_REPLACEMENT(newinstr, num) /* replacement */ \ "# ALT: replacement " #num "\n" \ b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n" +#define N_ALTINSTR_REPLACEMENT(newinstr) /* replacement */ \ + ".pushsection .altinstr_replacement, \"ax\"\n" \ + "# N_ALT: replacement\n" \ + "774:\n\t" newinstr "\n775:\n" \ + ".popsection\n" + /* alternative assembly primitive: */ #define ALTERNATIVE(oldinstr, newinstr, ft_flags) \ OLDINSTR(oldinstr, 1) \ @@ -223,6 +251,12 @@ static inline int alternatives_text_reserved(void *start, void *end) ALTINSTR_REPLACEMENT(newinstr, 1) \ ".popsection\n" +/* Nested alternatives macro variant */ +#define N_ALTERNATIVE(oldinstr, newinstr, ft_flags) \ + N_OLDINSTR(oldinstr) \ + N_ALTINSTR_ENTRY(ft_flags) \ + N_ALTINSTR_REPLACEMENT(newinstr) + #define ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \ OLDINSTR_2(oldinstr, 1, 2) \ ".pushsection .altinstructions,\"a\"\n" \ @@ -234,11 +268,21 @@ static inline int alternatives_text_reserved(void *start, void *end) ALTINSTR_REPLACEMENT(newinstr2, 2) \ ".popsection\n" +#define N_ALTERNATIVE_2(oldinst, newinst1, flag1, newinst2, flag2) \ + N_ALTERNATIVE(N_ALTERNATIVE(oldinst, newinst1, flag1), \ + newinst2, flag2) + /* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ #define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \ ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \ newinstr_yes, ft_flags) +/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ +#define N_ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \ + N_ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \ + newinstr_yes, ft_flags) + + #define ALTERNATIVE_3(oldinsn, newinsn1, ft_flags1, newinsn2, ft_flags2, \ newinsn3, ft_flags3) \ OLDINSTR_3(oldinsn, 1, 2, 3) \ @@ -253,6 +297,12 @@ static inline int alternatives_text_reserved(void *start, void *end) ALTINSTR_REPLACEMENT(newinsn3, 3) \ ".popsection\n" + +#define N_ALTERNATIVE_3(oldinst, newinst1, flag1, newinst2, flag2, \ + newinst3, flag3) \ + N_ALTERNATIVE(N_ALTERNATIVE_2(oldinst, newinst1, flag1, newinst2, flag2), \ + newinst3, flag3) + /* * Alternative instructions for different CPU types or capabilities. * @@ -271,6 +321,12 @@ static inline int alternatives_text_reserved(void *start, void *end) #define alternative_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \ asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) ::: "memory") +#define n_alternative(oldinstr, newinstr, ft_flags) \ + asm_inline volatile (N_ALTERNATIVE(oldinstr, newinstr, ft_flags) : : : "memory") + +#define n_alternative_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \ + asm_inline volatile(N_ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) ::: "memory") + /* * Alternative inline assembly with input. * @@ -288,11 +344,32 @@ static inline int alternatives_text_reserved(void *start, void *end) asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \ : output : "i" (0), ## input) -/* Like alternative_io, but for replacing a direct call with another one. */ +#define n_alternative_io(oldinstr, newinstr, ft_flags, output, input...) \ + asm_inline volatile (N_ALTERNATIVE(oldinstr, newinstr, ft_flags) \ + : output : "i" (0), ## input) + +/* + * 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(oldfunc, newfunc, ft_flags, output, input...) \ asm_inline volatile (ALTERNATIVE("call %c[old]", "call %c[new]", ft_flags) \ : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input) +#define n_alternative_input(oldinstr, newinstr, ft_flags, input...) \ + asm_inline volatile (N_ALTERNATIVE(oldinstr, newinstr, ft_flags) \ + : : "i" (0), ## input) + +#define n_alternative_call(oldfunc, newfunc, ft_flags, output, input...) \ + asm_inline volatile (N_ALTERNATIVE("call %c[old]", "call %c[new]", ft_flags) \ + : 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. @@ -307,6 +384,15 @@ static inline int alternatives_text_reserved(void *start, void *end) : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ [new2] "i" (newfunc2), ## input) +#define n_alternative_call_2(oldfunc, newfunc1, ft_flags1, newfunc2, ft_flags2, \ + output, input...) \ + asm_inline volatile (N_ALTERNATIVE_2("call %c[old]", "call %c[new1]", ft_flags1,\ + "call %c[new2]", ft_flags2) \ + : 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 @@ -403,6 +489,27 @@ void nop_func(void); .popsection .endm +#define __N_ALTERNATIVE(oldinst, newinst, flag) \ +740: \ + oldinst ; \ +741: \ + .skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90 ;\ +742: \ + .pushsection .altinstructions,"a" ; \ + altinstr_entry 740b,743f,flag,742b-740b,744f-743f ; \ + .popsection ; \ + .pushsection .altinstr_replacement,"ax" ; \ +743: \ + newinst ; \ +744: \ + .popsection ; + + +.macro N_ALTERNATIVE oldinstr, newinstr, ft_flags + __N_ALTERNATIVE(\oldinstr, \newinstr, \ft_flags) +.endm + + #define old_len 141b-140b #define new_len1 144f-143f #define new_len2 145f-144f @@ -417,7 +524,6 @@ void nop_func(void); #define alt_max_2(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b))))) #define alt_max_3(a, b, c) (alt_max_2(alt_max_2(a, b), c)) - /* * Same as ALTERNATIVE macro above but for two alternatives. If CPU * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has @@ -445,6 +551,11 @@ void nop_func(void); .popsection .endm +.macro N_ALTERNATIVE_2 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2 + __N_ALTERNATIVE(__N_ALTERNATIVE(\oldinstr, \newinstr1, \ft_flags1), + \newinstr2, \ft_flags2) +.endm + .macro ALTERNATIVE_3 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, newinstr3, ft_flags3 140: \oldinstr @@ -470,6 +581,11 @@ void nop_func(void); .popsection .endm +.macro N_ALTERNATIVE_3 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, newinstr3, ft_flags3 + __N_ALTERNATIVE(N_ALTERNATIVE_2(\oldinstr, \newinstr1, \ft_flags1, \newinstr2, \ft_flags2), + \newinstr3, \ft_flags3) +.endm + /* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */ #define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \ ALTERNATIVE_2 oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 89de61243272..37596a417094 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -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); diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c index 4134d27c696b..4ea0f9815fda 100644 --- a/tools/objtool/arch/x86/special.c +++ b/tools/objtool/arch/x86/special.c @@ -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: /* diff --git a/tools/objtool/special.c b/tools/objtool/special.c index 91b1950f5bd8..097a69db82a0 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -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) { |