x86, cpu: Clean up and unify the NOP selection infrastructure
Clean up and unify the NOP selection infrastructure:
- Make the atomic 5-byte NOP a part of the selection system.
- Pick NOPs once during early boot and then be done with it.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/r/1303166160-10315-3-git-send-email-hpa@linux.intel.com
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4a23467..846f61e 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -67,17 +67,30 @@
#define DPRINTK(fmt, args...) if (debug_alternative) \
printk(KERN_DEBUG fmt, args)
+/*
+ * Each GENERIC_NOPX is of X bytes, and defined as an array of bytes
+ * that correspond to that nop. Getting from one nop to the next, we
+ * add to the array the offset that is equal to the sum of all sizes of
+ * nops preceding the one we are after.
+ *
+ * Note: The GENERIC_NOP5_ATOMIC is at the end, as it breaks the
+ * nice symmetry of sizes of the previous nops.
+ */
#if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64)
-/* Use inline assembly to define this because the nops are defined
- as inline assembly strings in the include files and we cannot
- get them easily into strings. */
-asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nintelnops: "
- GENERIC_NOP1 GENERIC_NOP2 GENERIC_NOP3 GENERIC_NOP4 GENERIC_NOP5 GENERIC_NOP6
- GENERIC_NOP7 GENERIC_NOP8
- "\t.previous");
-extern const unsigned char intelnops[];
-static const unsigned char *const __initconst_or_module
-intel_nops[ASM_NOP_MAX+1] = {
+static const unsigned char intelnops[] =
+{
+ GENERIC_NOP1,
+ GENERIC_NOP2,
+ GENERIC_NOP3,
+ GENERIC_NOP4,
+ GENERIC_NOP5,
+ GENERIC_NOP6,
+ GENERIC_NOP7,
+ GENERIC_NOP8,
+ GENERIC_NOP5_ATOMIC
+};
+static const unsigned char * const intel_nops[ASM_NOP_MAX+2] =
+{
NULL,
intelnops,
intelnops + 1,
@@ -87,17 +100,25 @@
intelnops + 1 + 2 + 3 + 4 + 5,
intelnops + 1 + 2 + 3 + 4 + 5 + 6,
intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+ intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
};
#endif
#ifdef K8_NOP1
-asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk8nops: "
- K8_NOP1 K8_NOP2 K8_NOP3 K8_NOP4 K8_NOP5 K8_NOP6
- K8_NOP7 K8_NOP8
- "\t.previous");
-extern const unsigned char k8nops[];
-static const unsigned char *const __initconst_or_module
-k8_nops[ASM_NOP_MAX+1] = {
+static const unsigned char k8nops[] =
+{
+ K8_NOP1,
+ K8_NOP2,
+ K8_NOP3,
+ K8_NOP4,
+ K8_NOP5,
+ K8_NOP6,
+ K8_NOP7,
+ K8_NOP8,
+ K8_NOP5_ATOMIC
+};
+static const unsigned char * const k8_nops[ASM_NOP_MAX+2] =
+{
NULL,
k8nops,
k8nops + 1,
@@ -107,17 +128,25 @@
k8nops + 1 + 2 + 3 + 4 + 5,
k8nops + 1 + 2 + 3 + 4 + 5 + 6,
k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+ k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
};
#endif
#if defined(K7_NOP1) && !defined(CONFIG_X86_64)
-asm("\t" __stringify(__INITRODATA_OR_MODULE) "\nk7nops: "
- K7_NOP1 K7_NOP2 K7_NOP3 K7_NOP4 K7_NOP5 K7_NOP6
- K7_NOP7 K7_NOP8
- "\t.previous");
-extern const unsigned char k7nops[];
-static const unsigned char *const __initconst_or_module
-k7_nops[ASM_NOP_MAX+1] = {
+static const unsigned char k7nops[] =
+{
+ K7_NOP1,
+ K7_NOP2,
+ K7_NOP3,
+ K7_NOP4,
+ K7_NOP5,
+ K7_NOP6,
+ K7_NOP7,
+ K7_NOP8,
+ K7_NOP5_ATOMIC
+};
+static const unsigned char * const k7_nops[ASM_NOP_MAX+2] =
+{
NULL,
k7nops,
k7nops + 1,
@@ -127,17 +156,25 @@
k7nops + 1 + 2 + 3 + 4 + 5,
k7nops + 1 + 2 + 3 + 4 + 5 + 6,
k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+ k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
};
#endif
#ifdef P6_NOP1
-asm("\t" __stringify(__INITRODATA_OR_MODULE) "\np6nops: "
- P6_NOP1 P6_NOP2 P6_NOP3 P6_NOP4 P6_NOP5 P6_NOP6
- P6_NOP7 P6_NOP8
- "\t.previous");
-extern const unsigned char p6nops[];
-static const unsigned char *const __initconst_or_module
-p6_nops[ASM_NOP_MAX+1] = {
+static const unsigned char __initconst_or_module p6nops[] =
+{
+ P6_NOP1,
+ P6_NOP2,
+ P6_NOP3,
+ P6_NOP4,
+ P6_NOP5,
+ P6_NOP6,
+ P6_NOP7,
+ P6_NOP8,
+ P6_NOP5_ATOMIC
+};
+static const unsigned char * const p6_nops[ASM_NOP_MAX+2] =
+{
NULL,
p6nops,
p6nops + 1,
@@ -147,47 +184,53 @@
p6nops + 1 + 2 + 3 + 4 + 5,
p6nops + 1 + 2 + 3 + 4 + 5 + 6,
p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
+ p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
};
#endif
+/* Initialize these to a safe default */
#ifdef CONFIG_X86_64
+const unsigned char * const *ideal_nops = p6_nops;
+#else
+const unsigned char * const *ideal_nops = intel_nops;
+#endif
-extern char __vsyscall_0;
-static const unsigned char *const *__init_or_module find_nop_table(void)
+void __init arch_init_ideal_nops(void)
{
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
- boot_cpu_has(X86_FEATURE_NOPL))
- return p6_nops;
- else
- return k8_nops;
+ switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_INTEL:
+ if (boot_cpu_has(X86_FEATURE_NOPL)) {
+ ideal_nops = p6_nops;
+ } else {
+#ifdef CONFIG_X86_64
+ ideal_nops = k8_nops;
+#else
+ ideal_nops = intel_nops;
+#endif
+ }
+
+ default:
+#ifdef CONFIG_X86_64
+ ideal_nops = k8_nops;
+#else
+ if (boot_cpu_has(X86_FEATURE_K8))
+ ideal_nops = k8_nops;
+ else if (boot_cpu_has(X86_FEATURE_K7))
+ ideal_nops = k7_nops;
+ else
+ ideal_nops = intel_nops;
+#endif
+ }
}
-#else /* CONFIG_X86_64 */
-
-static const unsigned char *const *__init_or_module find_nop_table(void)
-{
- if (boot_cpu_has(X86_FEATURE_K8))
- return k8_nops;
- else if (boot_cpu_has(X86_FEATURE_K7))
- return k7_nops;
- else if (boot_cpu_has(X86_FEATURE_NOPL))
- return p6_nops;
- else
- return intel_nops;
-}
-
-#endif /* CONFIG_X86_64 */
-
/* Use this to add nops to a buffer, then text_poke the whole buffer. */
static void __init_or_module add_nops(void *insns, unsigned int len)
{
- const unsigned char *const *noptable = find_nop_table();
-
while (len > 0) {
unsigned int noplen = len;
if (noplen > ASM_NOP_MAX)
noplen = ASM_NOP_MAX;
- memcpy(insns, noptable[noplen], noplen);
+ memcpy(insns, ideal_nops[noplen], noplen);
insns += noplen;
len -= noplen;
}
@@ -195,6 +238,7 @@
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern s32 __smp_locks[], __smp_locks_end[];
+extern char __vsyscall_0;
void *text_poke_early(void *addr, const void *opcode, size_t len);
/* Replace instructions with better alternatives for this CPU type.
@@ -678,29 +722,3 @@
wrote_text = 0;
__stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
}
-
-#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
-
-#ifdef CONFIG_X86_64
-unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 };
-#else
-unsigned char ideal_nop5[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
-#endif
-
-void __init arch_init_ideal_nop5(void)
-{
- /*
- * There is no good nop for all x86 archs. This selection
- * algorithm should be unified with the one in find_nop_table(),
- * but this should be good enough for now.
- *
- * For cases other than the ones below, use the safe (as in
- * always functional) defaults above.
- */
-#ifdef CONFIG_X86_64
- /* Don't use these on 32 bits due to broken virtualizers */
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
- memcpy(ideal_nop5, p6_nops[5], 5);
-#endif
-}
-#endif
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index a93742a..0ba15a6 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -260,9 +260,9 @@
return mod_code_status;
}
-static unsigned char *ftrace_nop_replace(void)
+static const unsigned char *ftrace_nop_replace(void)
{
- return ideal_nop5;
+ return ideal_nops[NOP_ATOMIC5];
}
static int
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 961b6b3..3fee346 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -34,7 +34,7 @@
code.offset = entry->target -
(entry->code + JUMP_LABEL_NOP_SIZE);
} else
- memcpy(&code, ideal_nop5, JUMP_LABEL_NOP_SIZE);
+ memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
get_online_cpus();
mutex_lock(&text_mutex);
text_poke_smp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
@@ -44,7 +44,8 @@
void arch_jump_label_text_poke_early(jump_label_t addr)
{
- text_poke_early((void *)addr, ideal_nop5, JUMP_LABEL_NOP_SIZE);
+ text_poke_early((void *)addr, ideal_nops[NOP_ATOMIC5],
+ JUMP_LABEL_NOP_SIZE);
}
#endif
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 5a0484a..390a663 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -691,8 +691,6 @@
void __init setup_arch(char **cmdline_p)
{
- unsigned long flags;
-
#ifdef CONFIG_X86_32
memcpy(&boot_cpu_data, &new_cpu_data, sizeof(new_cpu_data));
visws_early_detect();
@@ -1036,9 +1034,7 @@
mcheck_init();
- local_irq_save(flags);
- arch_init_ideal_nop5();
- local_irq_restore(flags);
+ arch_init_ideal_nops();
}
#ifdef CONFIG_X86_32