diff options
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/include/asm/alternative.h | 14 | ||||
-rw-r--r-- | arch/x86/include/asm/cpufeature.h | 8 | ||||
-rw-r--r-- | arch/x86/include/asm/text-patching.h | 2 | ||||
-rw-r--r-- | arch/x86/kernel/alternative.c | 133 | ||||
-rw-r--r-- | arch/x86/kernel/callthunks.c | 9 | ||||
-rw-r--r-- | arch/x86/kernel/cpu/cpuid-deps.c | 3 |
6 files changed, 71 insertions, 98 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index 0cb2396de066..ba99ef75f56c 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -286,20 +286,6 @@ static inline int alternatives_text_reserved(void *start, void *end) asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \ : : "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, ft_flags1, newinstr2, \ - ft_flags2, input...) \ - asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, \ - newinstr2, ft_flags2) \ - : : "i" (0), ## input) - /* Like alternative_input, but with a single output argument */ #define alternative_io(oldinstr, newinstr, ft_flags, output, input...) \ asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \ diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index b96f9cabea0c..0b9611da6c53 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -149,8 +149,12 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; extern void setup_clear_cpu_cap(unsigned int bit); extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit); -#define setup_force_cpu_cap(bit) do { \ - set_cpu_cap(&boot_cpu_data, bit); \ +#define setup_force_cpu_cap(bit) do { \ + \ + if (!boot_cpu_has(bit)) \ + WARN_ON(alternatives_patched); \ + \ + set_cpu_cap(&boot_cpu_data, bit); \ set_bit(bit, (unsigned long *)cpu_caps_set); \ } while (0) diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h index 345aafbc1964..6259f1937fe7 100644 --- a/arch/x86/include/asm/text-patching.h +++ b/arch/x86/include/asm/text-patching.h @@ -15,7 +15,7 @@ extern void text_poke_early(void *addr, const void *opcode, size_t len); -extern void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len); +extern void apply_relocation(u8 *buf, const u8 * const instr, size_t instrlen, u8 *repl, size_t repl_len); /* * Clear and restore the kernel write-protection flag on the local CPU. diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 45a280f2161c..7555c15b7183 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -125,6 +125,20 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] = }; /* + * Nomenclature for variable names to simplify and clarify this code and ease + * any potential staring at it: + * + * @instr: source address of the original instructions in the kernel text as + * generated by the compiler. + * + * @buf: temporary buffer on which the patching operates. This buffer is + * eventually text-poked into the kernel image. + * + * @replacement/@repl: pointer to the opcodes which are replacing @instr, located + * in the .altinstr_replacement section. + */ + +/* * Fill the buffer with a single effective instruction of size @len. * * In order not to issue an ORC stack depth tracking CFI entry (Call Frame Info) @@ -133,28 +147,28 @@ const unsigned char * const x86_nops[ASM_NOP_MAX+1] = * each single-byte NOPs). If @len to fill out is > ASM_NOP_MAX, pad with INT3 and * *jump* over instead of executing long and daft NOPs. */ -static void add_nop(u8 *instr, unsigned int len) +static void add_nop(u8 *buf, unsigned int len) { - u8 *target = instr + len; + u8 *target = buf + len; if (!len) return; if (len <= ASM_NOP_MAX) { - memcpy(instr, x86_nops[len], len); + memcpy(buf, x86_nops[len], len); return; } if (len < 128) { - __text_gen_insn(instr, JMP8_INSN_OPCODE, instr, target, JMP8_INSN_SIZE); - instr += JMP8_INSN_SIZE; + __text_gen_insn(buf, JMP8_INSN_OPCODE, buf, target, JMP8_INSN_SIZE); + buf += JMP8_INSN_SIZE; } else { - __text_gen_insn(instr, JMP32_INSN_OPCODE, instr, target, JMP32_INSN_SIZE); - instr += JMP32_INSN_SIZE; + __text_gen_insn(buf, JMP32_INSN_OPCODE, buf, target, JMP32_INSN_SIZE); + buf += JMP32_INSN_SIZE; } - for (;instr < target; instr++) - *instr = INT3_INSN_OPCODE; + for (;buf < target; buf++) + *buf = INT3_INSN_OPCODE; } extern s32 __retpoline_sites[], __retpoline_sites_end[]; @@ -187,12 +201,12 @@ static bool insn_is_nop(struct insn *insn) * Find the offset of the first non-NOP instruction starting at @offset * but no further than @len. */ -static int skip_nops(u8 *instr, int offset, int len) +static int skip_nops(u8 *buf, int offset, int len) { struct insn insn; for (; offset < len; offset += insn.length) { - if (insn_decode_kernel(&insn, &instr[offset])) + if (insn_decode_kernel(&insn, &buf[offset])) break; if (!insn_is_nop(&insn)) @@ -203,66 +217,32 @@ static int skip_nops(u8 *instr, int offset, int len) } /* - * Optimize a sequence of NOPs, possibly preceded by an unconditional jump - * to the end of the NOP sequence into a single NOP. - */ -static bool -__optimize_nops(u8 *instr, size_t len, struct insn *insn, int *next, int *prev, int *target) -{ - int i = *next - insn->length; - - switch (insn->opcode.bytes[0]) { - case JMP8_INSN_OPCODE: - case JMP32_INSN_OPCODE: - *prev = i; - *target = *next + insn->immediate.value; - return false; - } - - if (insn_is_nop(insn)) { - int nop = i; - - *next = skip_nops(instr, *next, len); - if (*target && *next == *target) - nop = *prev; - - add_nop(instr + nop, *next - nop); - DUMP_BYTES(ALT, instr, len, "%px: [%d:%d) optimized NOPs: ", instr, nop, *next); - return true; - } - - *target = 0; - return false; -} - -/* * "noinline" to cause control flow change and thus invalidate I$ and * cause refetch after modification. */ -static void __init_or_module noinline optimize_nops(u8 *instr, size_t len) +static void noinline optimize_nops(const u8 * const instr, u8 *buf, size_t len) { - int prev, target = 0; - for (int next, i = 0; i < len; i = next) { struct insn insn; - if (insn_decode_kernel(&insn, &instr[i])) + if (insn_decode_kernel(&insn, &buf[i])) return; next = i + insn.length; - __optimize_nops(instr, len, &insn, &next, &prev, &target); - } -} + if (insn_is_nop(&insn)) { + int nop = i; -static void __init_or_module noinline optimize_nops_inplace(u8 *instr, size_t len) -{ - unsigned long flags; + /* Has the NOP already been optimized? */ + if (i + insn.length == len) + return; - local_irq_save(flags); - optimize_nops(instr, len); - sync_core(); - local_irq_restore(flags); + next = skip_nops(buf, next, len); + + add_nop(buf + nop, next - nop); + DUMP_BYTES(ALT, buf, len, "%px: [%d:%d) optimized NOPs: ", instr, nop, next); + } + } } /* @@ -335,11 +315,9 @@ bool need_reloc(unsigned long offset, u8 *src, size_t src_len) return (target < src || target > src + src_len); } -void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) +static void __apply_relocation(u8 *buf, const u8 * const instr, size_t instrlen, u8 *repl, size_t repl_len) { - int prev, target = 0; - - for (int next, i = 0; i < len; i = next) { + for (int next, i = 0; i < instrlen; i = next) { struct insn insn; if (WARN_ON_ONCE(insn_decode_kernel(&insn, &buf[i]))) @@ -347,9 +325,6 @@ void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) next = i + insn.length; - if (__optimize_nops(buf, len, &insn, &next, &prev, &target)) - continue; - switch (insn.opcode.bytes[0]) { case 0x0f: if (insn.opcode.bytes[1] < 0x80 || @@ -361,10 +336,10 @@ void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) case JMP8_INSN_OPCODE: case JMP32_INSN_OPCODE: case CALL_INSN_OPCODE: - if (need_reloc(next + insn.immediate.value, src, src_len)) { + if (need_reloc(next + insn.immediate.value, repl, repl_len)) { apply_reloc(insn.immediate.nbytes, buf + i + insn_offset_immediate(&insn), - src - dest); + repl - instr); } /* @@ -372,7 +347,7 @@ void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) */ if (insn.opcode.bytes[0] == JMP32_INSN_OPCODE) { s32 imm = insn.immediate.value; - imm += src - dest; + imm += repl - instr; imm += JMP32_INSN_SIZE - JMP8_INSN_SIZE; if ((imm >> 31) == (imm >> 7)) { buf[i+0] = JMP8_INSN_OPCODE; @@ -385,15 +360,21 @@ void apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len) } if (insn_rip_relative(&insn)) { - if (need_reloc(next + insn.displacement.value, src, src_len)) { + if (need_reloc(next + insn.displacement.value, repl, repl_len)) { apply_reloc(insn.displacement.nbytes, buf + i + insn_offset_displacement(&insn), - src - dest); + repl - instr); } } } } +void apply_relocation(u8 *buf, const u8 * const instr, size_t instrlen, u8 *repl, size_t repl_len) +{ + __apply_relocation(buf, instr, instrlen, repl, repl_len); + optimize_nops(instr, buf, repl_len); +} + /* Low-level backend functions usable from alternative code replacements. */ DEFINE_ASM_FUNC(nop_func, "", .entry.text); EXPORT_SYMBOL_GPL(nop_func); @@ -464,9 +445,9 @@ static int alt_replace_call(u8 *instr, u8 *insn_buff, struct alt_instr *a) void __init_or_module noinline apply_alternatives(struct alt_instr *start, struct alt_instr *end) { - struct alt_instr *a; - u8 *instr, *replacement; u8 insn_buff[MAX_PATCH_LEN]; + u8 *instr, *replacement; + struct alt_instr *a; DPRINTK(ALT, "alt table %px, -> %px", start, end); @@ -504,7 +485,9 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, * patch if feature is *NOT* present. */ if (!boot_cpu_has(a->cpuid) == !(a->flags & ALT_FLAG_NOT)) { - optimize_nops_inplace(instr, a->instrlen); + memcpy(insn_buff, instr, a->instrlen); + optimize_nops(instr, insn_buff, a->instrlen); + text_poke_early(instr, insn_buff, a->instrlen); continue; } @@ -526,7 +509,7 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start, for (; insn_buff_sz < a->instrlen; insn_buff_sz++) insn_buff[insn_buff_sz] = 0x90; - apply_relocation(insn_buff, a->instrlen, instr, replacement, a->replacementlen); + apply_relocation(insn_buff, instr, a->instrlen, replacement, a->replacementlen); DUMP_BYTES(ALT, instr, a->instrlen, "%px: old_insn: ", instr); DUMP_BYTES(ALT, replacement, a->replacementlen, "%px: rpl_insn: ", replacement); @@ -761,7 +744,7 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end) len = patch_retpoline(addr, &insn, bytes); if (len == insn.length) { - optimize_nops(bytes, len); + optimize_nops(addr, bytes, len); DUMP_BYTES(RETPOLINE, ((u8*)addr), len, "%px: orig: ", addr); DUMP_BYTES(RETPOLINE, ((u8*)bytes), len, "%px: repl: ", addr); text_poke_early(addr, bytes, len); diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index e92ff0c11db8..465647456753 100644 --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -185,8 +185,7 @@ static void *patch_dest(void *dest, bool direct) u8 *pad = dest - tsize; memcpy(insn_buff, skl_call_thunk_template, tsize); - apply_relocation(insn_buff, tsize, pad, - skl_call_thunk_template, tsize); + apply_relocation(insn_buff, pad, tsize, skl_call_thunk_template, tsize); /* Already patched? */ if (!bcmp(pad, insn_buff, tsize)) @@ -308,8 +307,7 @@ static bool is_callthunk(void *addr) pad = (void *)(dest - tmpl_size); memcpy(insn_buff, skl_call_thunk_template, tmpl_size); - apply_relocation(insn_buff, tmpl_size, pad, - skl_call_thunk_template, tmpl_size); + apply_relocation(insn_buff, pad, tmpl_size, skl_call_thunk_template, tmpl_size); return !bcmp(pad, insn_buff, tmpl_size); } @@ -327,8 +325,7 @@ int x86_call_depth_emit_accounting(u8 **pprog, void *func, void *ip) return 0; memcpy(insn_buff, skl_call_thunk_template, tmpl_size); - apply_relocation(insn_buff, tmpl_size, ip, - skl_call_thunk_template, tmpl_size); + apply_relocation(insn_buff, ip, tmpl_size, skl_call_thunk_template, tmpl_size); memcpy(*pprog, insn_buff, tmpl_size); *pprog += tmpl_size; diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c index 946813d816bf..b7d9f530ae16 100644 --- a/arch/x86/kernel/cpu/cpuid-deps.c +++ b/arch/x86/kernel/cpu/cpuid-deps.c @@ -114,6 +114,9 @@ static void do_clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature) if (WARN_ON(feature >= MAX_FEATURE_BITS)) return; + if (boot_cpu_has(feature)) + WARN_ON(alternatives_patched); + clear_feature(c, feature); /* Collect all features to disable, handling dependencies */ |