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Subject[PATCH 5/7] x86/cpu: Move early cpu initialization into a separate translation unit
Date
__pgtable_l5_enabled shouldn't be needed after system has booted, we can
mark it as __initdata, but it requires preparation.

This patch moves early cpu initialization into a separate translation
unit. This limits effect of USE_EARLY_PGTABLE_L5 to less code.

Without the change cpu_init() uses __pgtable_l5_enabled. cpu_init() is
not __init function and it leads to section mismatch.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/x86/kernel/cpu/Makefile | 1 +
arch/x86/kernel/cpu/common.c | 194 ++++-------------------------------
arch/x86/kernel/cpu/cpu.h | 7 ++
arch/x86/kernel/cpu/early.c | 159 ++++++++++++++++++++++++++++
4 files changed, 189 insertions(+), 172 deletions(-)
create mode 100644 arch/x86/kernel/cpu/early.c

diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
index a66229f51b12..6d88889706a8 100644
--- a/arch/x86/kernel/cpu/Makefile
+++ b/arch/x86/kernel/cpu/Makefile
@@ -19,6 +19,7 @@ CFLAGS_common.o := $(nostackp)

obj-y := intel_cacheinfo.o scattered.o topology.o
obj-y += common.o
+obj-y += early.o
obj-y += rdrand.o
obj-y += match.o
obj-y += bugs.o
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a32f3c02327f..381675c7e485 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -47,7 +47,6 @@
#include <asm/pat.h>
#include <asm/microcode.h>
#include <asm/microcode_intel.h>
-#include <asm/intel-family.h>
#include <asm/cpu_device_id.h>

#ifdef CONFIG_X86_LOCAL_APIC
@@ -98,7 +97,7 @@ static const struct cpu_dev default_cpu = {
.c_x86_vendor = X86_VENDOR_UNKNOWN,
};

-static const struct cpu_dev *this_cpu = &default_cpu;
+const struct cpu_dev *this_cpu_dev = &default_cpu;

DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
#ifdef CONFIG_X86_64
@@ -419,7 +418,7 @@ cpuid_dependent_features[] = {
{ 0, 0 }
};

-static void filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
+void filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
{
const struct cpuid_dependent_feature *df;

@@ -464,10 +463,10 @@ static const char *table_lookup_model(struct cpuinfo_x86 *c)
if (c->x86_model >= 16)
return NULL; /* Range check */

- if (!this_cpu)
+ if (!this_cpu_dev)
return NULL;

- info = this_cpu->legacy_models;
+ info = this_cpu_dev->legacy_models;

while (info->family) {
if (info->family == c->x86)
@@ -544,7 +543,7 @@ void switch_to_new_gdt(int cpu)
load_percpu_segment(cpu);
}

-static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
+const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};

static void get_model_name(struct cpuinfo_x86 *c)
{
@@ -602,8 +601,8 @@ void cpu_detect_cache_sizes(struct cpuinfo_x86 *c)
c->x86_tlbsize += ((ebx >> 16) & 0xfff) + (ebx & 0xfff);
#else
/* do processor-specific cache resizing */
- if (this_cpu->legacy_cache_size)
- l2size = this_cpu->legacy_cache_size(c, l2size);
+ if (this_cpu_dev->legacy_cache_size)
+ l2size = this_cpu_dev->legacy_cache_size(c, l2size);

/* Allow user to override all this if necessary. */
if (cachesize_override != -1)
@@ -626,8 +625,8 @@ u16 __read_mostly tlb_lld_1g[NR_INFO];

static void cpu_detect_tlb(struct cpuinfo_x86 *c)
{
- if (this_cpu->c_detect_tlb)
- this_cpu->c_detect_tlb(c);
+ if (this_cpu_dev->c_detect_tlb)
+ this_cpu_dev->c_detect_tlb(c);

pr_info("Last level iTLB entries: 4KB %d, 2MB %d, 4MB %d\n",
tlb_lli_4k[ENTRIES], tlb_lli_2m[ENTRIES],
@@ -689,7 +688,7 @@ void detect_ht(struct cpuinfo_x86 *c)
#endif
}

-static void get_cpu_vendor(struct cpuinfo_x86 *c)
+void get_cpu_vendor(struct cpuinfo_x86 *c)
{
char *v = c->x86_vendor_id;
int i;
@@ -702,8 +701,8 @@ static void get_cpu_vendor(struct cpuinfo_x86 *c)
(cpu_devs[i]->c_ident[1] &&
!strcmp(v, cpu_devs[i]->c_ident[1]))) {

- this_cpu = cpu_devs[i];
- c->x86_vendor = this_cpu->c_x86_vendor;
+ this_cpu_dev = cpu_devs[i];
+ c->x86_vendor = this_cpu_dev->c_x86_vendor;
return;
}
}
@@ -712,7 +711,7 @@ static void get_cpu_vendor(struct cpuinfo_x86 *c)
"CPU: Your system may be unstable.\n", v);

c->x86_vendor = X86_VENDOR_UNKNOWN;
- this_cpu = &default_cpu;
+ this_cpu_dev = &default_cpu;
}

void cpu_detect(struct cpuinfo_x86 *c)
@@ -867,7 +866,7 @@ void get_cpu_cap(struct cpuinfo_x86 *c)
apply_forced_caps(c);
}

-static void get_cpu_address_sizes(struct cpuinfo_x86 *c)
+void get_cpu_address_sizes(struct cpuinfo_x86 *c)
{
u32 eax, ebx, ecx, edx;

@@ -883,7 +882,7 @@ static void get_cpu_address_sizes(struct cpuinfo_x86 *c)
#endif
}

-static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
+void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_32
int i;
@@ -909,155 +908,6 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
#endif
}

-static const __initconst struct x86_cpu_id cpu_no_speculation[] = {
- { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW, X86_FEATURE_ANY },
- { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW, X86_FEATURE_ANY },
- { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT, X86_FEATURE_ANY },
- { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL, X86_FEATURE_ANY },
- { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW, X86_FEATURE_ANY },
- { X86_VENDOR_CENTAUR, 5 },
- { X86_VENDOR_INTEL, 5 },
- { X86_VENDOR_NSC, 5 },
- { X86_VENDOR_ANY, 4 },
- {}
-};
-
-static const __initconst struct x86_cpu_id cpu_no_meltdown[] = {
- { X86_VENDOR_AMD },
- {}
-};
-
-static bool __init cpu_vulnerable_to_meltdown(struct cpuinfo_x86 *c)
-{
- u64 ia32_cap = 0;
-
- if (x86_match_cpu(cpu_no_meltdown))
- return false;
-
- if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
- rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
-
- /* Rogue Data Cache Load? No! */
- if (ia32_cap & ARCH_CAP_RDCL_NO)
- return false;
-
- return true;
-}
-
-/*
- * Do minimum CPU detection early.
- * Fields really needed: vendor, cpuid_level, family, model, mask,
- * cache alignment.
- * The others are not touched to avoid unwanted side effects.
- *
- * WARNING: this function is only called on the boot CPU. Don't add code
- * here that is supposed to run on all CPUs.
- */
-static void __init early_identify_cpu(struct cpuinfo_x86 *c)
-{
-#ifdef CONFIG_X86_64
- c->x86_clflush_size = 64;
- c->x86_phys_bits = 36;
- c->x86_virt_bits = 48;
-#else
- c->x86_clflush_size = 32;
- c->x86_phys_bits = 32;
- c->x86_virt_bits = 32;
-#endif
- c->x86_cache_alignment = c->x86_clflush_size;
-
- memset(&c->x86_capability, 0, sizeof c->x86_capability);
- c->extended_cpuid_level = 0;
-
- /* cyrix could have cpuid enabled via c_identify()*/
- if (have_cpuid_p()) {
- cpu_detect(c);
- get_cpu_vendor(c);
- get_cpu_cap(c);
- get_cpu_address_sizes(c);
- setup_force_cpu_cap(X86_FEATURE_CPUID);
-
- if (this_cpu->c_early_init)
- this_cpu->c_early_init(c);
-
- c->cpu_index = 0;
- filter_cpuid_features(c, false);
-
- if (this_cpu->c_bsp_init)
- this_cpu->c_bsp_init(c);
- } else {
- identify_cpu_without_cpuid(c);
- setup_clear_cpu_cap(X86_FEATURE_CPUID);
- }
-
- setup_force_cpu_cap(X86_FEATURE_ALWAYS);
-
- if (!x86_match_cpu(cpu_no_speculation)) {
- if (cpu_vulnerable_to_meltdown(c))
- setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
- setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
- setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
- }
-
- fpu__init_system(c);
-
-#ifdef CONFIG_X86_32
- /*
- * Regardless of whether PCID is enumerated, the SDM says
- * that it can't be enabled in 32-bit mode.
- */
- setup_clear_cpu_cap(X86_FEATURE_PCID);
-#endif
-
- /*
- * Later in the boot process pgtable_l5_enabled() relies on
- * cpu_feature_enabled(X86_FEATURE_LA57). If 5-level paging is not
- * enabled by this point we need to clear the feature bit to avoid
- * false-positives at the later stage.
- *
- * pgtable_l5_enabled() can be false here for several reasons:
- * - 5-level paging is disabled compile-time;
- * - it's 32-bit kernel;
- * - machine doesn't support 5-level paging;
- * - user specified 'no5lvl' in kernel command line.
- */
- if (!pgtable_l5_enabled())
- setup_clear_cpu_cap(X86_FEATURE_LA57);
-}
-
-void __init early_cpu_init(void)
-{
- const struct cpu_dev *const *cdev;
- int count = 0;
-
-#ifdef CONFIG_PROCESSOR_SELECT
- pr_info("KERNEL supported cpus:\n");
-#endif
-
- for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
- const struct cpu_dev *cpudev = *cdev;
-
- if (count >= X86_VENDOR_NUM)
- break;
- cpu_devs[count] = cpudev;
- count++;
-
-#ifdef CONFIG_PROCESSOR_SELECT
- {
- unsigned int j;
-
- for (j = 0; j < 2; j++) {
- if (!cpudev->c_ident[j])
- continue;
- pr_info(" %s %s\n", cpudev->c_vendor,
- cpudev->c_ident[j]);
- }
- }
-#endif
- }
- early_identify_cpu(&boot_cpu_data);
-}
-
/*
* The NOPL instruction is supposed to exist on all CPUs of family >= 6;
* unfortunately, that's not true in practice because of early VIA
@@ -1234,8 +1084,8 @@ static void identify_cpu(struct cpuinfo_x86 *c)

generic_identify(c);

- if (this_cpu->c_identify)
- this_cpu->c_identify(c);
+ if (this_cpu_dev->c_identify)
+ this_cpu_dev->c_identify(c);

/* Clear/Set all flags overridden by options, after probe */
apply_forced_caps(c);
@@ -1254,8 +1104,8 @@ static void identify_cpu(struct cpuinfo_x86 *c)
* At the end of this section, c->x86_capability better
* indicate the features this CPU genuinely supports!
*/
- if (this_cpu->c_init)
- this_cpu->c_init(c);
+ if (this_cpu_dev->c_init)
+ this_cpu_dev->c_init(c);

/* Disable the PN if appropriate */
squash_the_stupid_serial_number(c);
@@ -1389,7 +1239,7 @@ void print_cpu_info(struct cpuinfo_x86 *c)
const char *vendor = NULL;

if (c->x86_vendor < X86_VENDOR_NUM) {
- vendor = this_cpu->c_vendor;
+ vendor = this_cpu_dev->c_vendor;
} else {
if (c->cpuid_level >= 0)
vendor = c->x86_vendor_id;
@@ -1763,8 +1613,8 @@ void cpu_init(void)

static void bsp_resume(void)
{
- if (this_cpu->c_bsp_resume)
- this_cpu->c_bsp_resume(&boot_cpu_data);
+ if (this_cpu_dev->c_bsp_resume)
+ this_cpu_dev->c_bsp_resume(&boot_cpu_data);
}

static struct syscore_ops cpu_syscore_ops = {
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index e806b11a99af..d633835b59ee 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -45,8 +45,15 @@ struct _tlb_table {
extern const struct cpu_dev *const __x86_cpu_dev_start[],
*const __x86_cpu_dev_end[];

+extern const struct cpu_dev *cpu_devs[];
+extern const struct cpu_dev *this_cpu_dev;
+
extern void get_cpu_cap(struct cpuinfo_x86 *c);
+extern void get_cpu_vendor(struct cpuinfo_x86 *c);
+extern void get_cpu_address_sizes(struct cpuinfo_x86 *c);
extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
+extern void identify_cpu_without_cpuid(struct cpuinfo_x86 *c);
+extern void filter_cpuid_features(struct cpuinfo_x86 *c, bool warn);

unsigned int aperfmperf_get_khz(int cpu);

diff --git a/arch/x86/kernel/cpu/early.c b/arch/x86/kernel/cpu/early.c
new file mode 100644
index 000000000000..cb42c1d909f6
--- /dev/null
+++ b/arch/x86/kernel/cpu/early.c
@@ -0,0 +1,159 @@
+#include <linux/linkage.h>
+#include <linux/kernel.h>
+
+#include <asm/processor.h>
+#include <asm/cpu.h>
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+#include <asm/fpu/internal.h>
+
+#include "cpu.h"
+
+static const __initconst struct x86_cpu_id cpu_no_speculation[] = {
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CEDARVIEW, X86_FEATURE_ANY },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_CLOVERVIEW, X86_FEATURE_ANY },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_LINCROFT, X86_FEATURE_ANY },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PENWELL, X86_FEATURE_ANY },
+ { X86_VENDOR_INTEL, 6, INTEL_FAM6_ATOM_PINEVIEW, X86_FEATURE_ANY },
+ { X86_VENDOR_CENTAUR, 5 },
+ { X86_VENDOR_INTEL, 5 },
+ { X86_VENDOR_NSC, 5 },
+ { X86_VENDOR_ANY, 4 },
+ {}
+};
+
+static const __initconst struct x86_cpu_id cpu_no_meltdown[] = {
+ { X86_VENDOR_AMD },
+ {}
+};
+
+static bool __init cpu_vulnerable_to_meltdown(struct cpuinfo_x86 *c)
+{
+ u64 ia32_cap = 0;
+
+ if (x86_match_cpu(cpu_no_meltdown))
+ return false;
+
+ if (cpu_has(c, X86_FEATURE_ARCH_CAPABILITIES))
+ rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
+
+ /* Rogue Data Cache Load? No! */
+ if (ia32_cap & ARCH_CAP_RDCL_NO)
+ return false;
+
+ return true;
+}
+
+/*
+ * Do minimum CPU detection early.
+ * Fields really needed: vendor, cpuid_level, family, model, mask,
+ * cache alignment.
+ * The others are not touched to avoid unwanted side effects.
+ *
+ * WARNING: this function is only called on the boot CPU. Don't add code
+ * here that is supposed to run on all CPUs.
+ */
+static void __init early_identify_cpu(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_64
+ c->x86_clflush_size = 64;
+ c->x86_phys_bits = 36;
+ c->x86_virt_bits = 48;
+#else
+ c->x86_clflush_size = 32;
+ c->x86_phys_bits = 32;
+ c->x86_virt_bits = 32;
+#endif
+ c->x86_cache_alignment = c->x86_clflush_size;
+
+ memset(&c->x86_capability, 0, sizeof c->x86_capability);
+ c->extended_cpuid_level = 0;
+
+ /* cyrix could have cpuid enabled via c_identify()*/
+ if (have_cpuid_p()) {
+ cpu_detect(c);
+ get_cpu_vendor(c);
+ get_cpu_cap(c);
+ get_cpu_address_sizes(c);
+ setup_force_cpu_cap(X86_FEATURE_CPUID);
+
+ if (this_cpu_dev->c_early_init)
+ this_cpu_dev->c_early_init(c);
+
+ c->cpu_index = 0;
+ filter_cpuid_features(c, false);
+
+ if (this_cpu_dev->c_bsp_init)
+ this_cpu_dev->c_bsp_init(c);
+ } else {
+ identify_cpu_without_cpuid(c);
+ setup_clear_cpu_cap(X86_FEATURE_CPUID);
+ }
+
+ setup_force_cpu_cap(X86_FEATURE_ALWAYS);
+
+ if (!x86_match_cpu(cpu_no_speculation)) {
+ if (cpu_vulnerable_to_meltdown(c))
+ setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+ }
+
+ fpu__init_system(c);
+
+#ifdef CONFIG_X86_32
+ /*
+ * Regardless of whether PCID is enumerated, the SDM says
+ * that it can't be enabled in 32-bit mode.
+ */
+ setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
+
+ /*
+ * Later in the boot process pgtable_l5_enabled() relies on
+ * cpu_feature_enabled(X86_FEATURE_LA57). If 5-level paging is not
+ * enabled by this point we need to clear the feature bit to avoid
+ * false-positives at the later stage.
+ *
+ * pgtable_l5_enabled() can be false here for several reasons:
+ * - 5-level paging is disabled compile-time;
+ * - it's 32-bit kernel;
+ * - machine doesn't support 5-level paging;
+ * - user specified 'no5lvl' in kernel command line.
+ */
+ if (!pgtable_l5_enabled())
+ setup_clear_cpu_cap(X86_FEATURE_LA57);
+}
+
+void __init early_cpu_init(void)
+{
+ const struct cpu_dev *const *cdev;
+ int count = 0;
+
+#ifdef CONFIG_PROCESSOR_SELECT
+ pr_info("KERNEL supported cpus:\n");
+#endif
+
+ for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
+ const struct cpu_dev *cpudev = *cdev;
+
+ if (count >= X86_VENDOR_NUM)
+ break;
+ cpu_devs[count] = cpudev;
+ count++;
+
+#ifdef CONFIG_PROCESSOR_SELECT
+ {
+ unsigned int j;
+
+ for (j = 0; j < 2; j++) {
+ if (!cpudev->c_ident[j])
+ continue;
+ pr_info(" %s %s\n", cpudev->c_vendor,
+ cpudev->c_ident[j]);
+ }
+ }
+#endif
+ }
+ early_identify_cpu(&boot_cpu_data);
+}
--
2.17.0
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