Merge tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core x86 updates from Ingo Molnar:

 - The biggest change is the rework of the percpu code, to support the
   'Named Address Spaces' GCC feature, by Uros Bizjak:

      - This allows C code to access GS and FS segment relative memory
        via variables declared with such attributes, which allows the
        compiler to better optimize those accesses than the previous
        inline assembly code.

      - The series also includes a number of micro-optimizations for
        various percpu access methods, plus a number of cleanups of %gs
        accesses in assembly code.

      - These changes have been exposed to linux-next testing for the
        last ~5 months, with no known regressions in this area.

 - Fix/clean up __switch_to()'s broken but accidentally working handling
   of FPU switching - which also generates better code

 - Propagate more RIP-relative addressing in assembly code, to generate
   slightly better code

 - Rework the CPU mitigations Kconfig space to be less idiosyncratic, to
   make it easier for distros to follow & maintain these options

 - Rework the x86 idle code to cure RCU violations and to clean up the
   logic

 - Clean up the vDSO Makefile logic

 - Misc cleanups and fixes

* tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
  x86/idle: Select idle routine only once
  x86/idle: Let prefer_mwait_c1_over_halt() return bool
  x86/idle: Cleanup idle_setup()
  x86/idle: Clean up idle selection
  x86/idle: Sanitize X86_BUG_AMD_E400 handling
  sched/idle: Conditionally handle tick broadcast in default_idle_call()
  x86: Increase brk randomness entropy for 64-bit systems
  x86/vdso: Move vDSO to mmap region
  x86/vdso/kbuild: Group non-standard build attributes and primary object file rules together
  x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o
  x86/retpoline: Ensure default return thunk isn't used at runtime
  x86/vdso: Use CONFIG_COMPAT_32 to specify vdso32
  x86/vdso: Use $(addprefix ) instead of $(foreach )
  x86/vdso: Simplify obj-y addition
  x86/vdso: Consolidate targets and clean-files
  x86/bugs: Rename CONFIG_RETHUNK              => CONFIG_MITIGATION_RETHUNK
  x86/bugs: Rename CONFIG_CPU_SRSO             => CONFIG_MITIGATION_SRSO
  x86/bugs: Rename CONFIG_CPU_IBRS_ENTRY       => CONFIG_MITIGATION_IBRS_ENTRY
  x86/bugs: Rename CONFIG_CPU_UNRET_ENTRY      => CONFIG_MITIGATION_UNRET_ENTRY
  x86/bugs: Rename CONFIG_SLS                  => CONFIG_MITIGATION_SLS
  ...

3 files changed, 31 insertions, 24 deletions

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index f8ae10222fd0..3282a747b645 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -817,7 +817,7 @@ static void fix_erratum_1386(struct cpuinfo_x86 *c)
 
 void init_spectral_chicken(struct cpuinfo_x86 *c)
 {
-#ifdef CONFIG_CPU_UNRET_ENTRY
+#ifdef CONFIG_MITIGATION_UNRET_ENTRY
 	u64 value;
 
 	/*
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 0767ab63ca63..4dd00066c12a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -668,7 +668,7 @@ enum gds_mitigations {
 	GDS_MITIGATION_HYPERVISOR,
 };
 
-#if IS_ENABLED(CONFIG_GDS_FORCE_MITIGATION)
+#if IS_ENABLED(CONFIG_MITIGATION_GDS_FORCE)
 static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FORCE;
 #else
 static enum gds_mitigations gds_mitigation __ro_after_init = GDS_MITIGATION_FULL;
@@ -979,10 +979,10 @@ static void __init retbleed_select_mitigation(void)
 		return;
 
 	case RETBLEED_CMD_UNRET:
-		if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY)) {
+		if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) {
 			retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
 		} else {
-			pr_err("WARNING: kernel not compiled with CPU_UNRET_ENTRY.\n");
+			pr_err("WARNING: kernel not compiled with MITIGATION_UNRET_ENTRY.\n");
 			goto do_cmd_auto;
 		}
 		break;
@@ -991,24 +991,24 @@ static void __init retbleed_select_mitigation(void)
 		if (!boot_cpu_has(X86_FEATURE_IBPB)) {
 			pr_err("WARNING: CPU does not support IBPB.\n");
 			goto do_cmd_auto;
-		} else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) {
+		} else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) {
 			retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
 		} else {
-			pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n");
+			pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n");
 			goto do_cmd_auto;
 		}
 		break;
 
 	case RETBLEED_CMD_STUFF:
-		if (IS_ENABLED(CONFIG_CALL_DEPTH_TRACKING) &&
+		if (IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) &&
 		    spectre_v2_enabled == SPECTRE_V2_RETPOLINE) {
 			retbleed_mitigation = RETBLEED_MITIGATION_STUFF;
 
 		} else {
-			if (IS_ENABLED(CONFIG_CALL_DEPTH_TRACKING))
+			if (IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING))
 				pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n");
 			else
-				pr_err("WARNING: kernel not compiled with CALL_DEPTH_TRACKING.\n");
+				pr_err("WARNING: kernel not compiled with MITIGATION_CALL_DEPTH_TRACKING.\n");
 
 			goto do_cmd_auto;
 		}
@@ -1018,9 +1018,10 @@ do_cmd_auto:
 	case RETBLEED_CMD_AUTO:
 		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||
 		    boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) {
-			if (IS_ENABLED(CONFIG_CPU_UNRET_ENTRY))
+			if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY))
 				retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
-			else if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY) && boot_cpu_has(X86_FEATURE_IBPB))
+			else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) &&
+				 boot_cpu_has(X86_FEATURE_IBPB))
 				retbleed_mitigation = RETBLEED_MITIGATION_IBPB;
 		}
 
@@ -1099,7 +1100,7 @@ static enum spectre_v2_user_mitigation spectre_v2_user_stibp __ro_after_init =
 static enum spectre_v2_user_mitigation spectre_v2_user_ibpb __ro_after_init =
 	SPECTRE_V2_USER_NONE;
 
-#ifdef CONFIG_RETPOLINE
+#ifdef CONFIG_MITIGATION_RETPOLINE
 static bool spectre_v2_bad_module;
 
 bool retpoline_module_ok(bool has_retpoline)
@@ -1412,7 +1413,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 	     cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC ||
 	     cmd == SPECTRE_V2_CMD_EIBRS_LFENCE ||
 	     cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) &&
-	    !IS_ENABLED(CONFIG_RETPOLINE)) {
+	    !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) {
 		pr_err("%s selected but not compiled in. Switching to AUTO select\n",
 		       mitigation_options[i].option);
 		return SPECTRE_V2_CMD_AUTO;
@@ -1435,7 +1436,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 		return SPECTRE_V2_CMD_AUTO;
 	}
 
-	if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_CPU_IBRS_ENTRY)) {
+	if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) {
 		pr_err("%s selected but not compiled in. Switching to AUTO select\n",
 		       mitigation_options[i].option);
 		return SPECTRE_V2_CMD_AUTO;
@@ -1466,7 +1467,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 
 static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void)
 {
-	if (!IS_ENABLED(CONFIG_RETPOLINE)) {
+	if (!IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) {
 		pr_err("Kernel not compiled with retpoline; no mitigation available!");
 		return SPECTRE_V2_NONE;
 	}
@@ -1561,7 +1562,7 @@ static void __init spectre_v2_select_mitigation(void)
 			break;
 		}
 
-		if (IS_ENABLED(CONFIG_CPU_IBRS_ENTRY) &&
+		if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) &&
 		    boot_cpu_has_bug(X86_BUG_RETBLEED) &&
 		    retbleed_cmd != RETBLEED_CMD_OFF &&
 		    retbleed_cmd != RETBLEED_CMD_STUFF &&
@@ -2454,7 +2455,7 @@ static void __init srso_select_mitigation(void)
 		break;
 
 	case SRSO_CMD_SAFE_RET:
-		if (IS_ENABLED(CONFIG_CPU_SRSO)) {
+		if (IS_ENABLED(CONFIG_MITIGATION_SRSO)) {
 			/*
 			 * Enable the return thunk for generated code
 			 * like ftrace, static_call, etc.
@@ -2474,29 +2475,29 @@ static void __init srso_select_mitigation(void)
 			else
 				srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED;
 		} else {
-			pr_err("WARNING: kernel not compiled with CPU_SRSO.\n");
+			pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
 		}
 		break;
 
 	case SRSO_CMD_IBPB:
-		if (IS_ENABLED(CONFIG_CPU_IBPB_ENTRY)) {
+		if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) {
 			if (has_microcode) {
 				setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
 				srso_mitigation = SRSO_MITIGATION_IBPB;
 			}
 		} else {
-			pr_err("WARNING: kernel not compiled with CPU_IBPB_ENTRY.\n");
+			pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n");
 		}
 		break;
 
 	case SRSO_CMD_IBPB_ON_VMEXIT:
-		if (IS_ENABLED(CONFIG_CPU_SRSO)) {
+		if (IS_ENABLED(CONFIG_MITIGATION_SRSO)) {
 			if (!boot_cpu_has(X86_FEATURE_ENTRY_IBPB) && has_microcode) {
 				setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);
 				srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
 			}
 		} else {
-			pr_err("WARNING: kernel not compiled with CPU_SRSO.\n");
+			pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
                 }
 		break;
 	}
@@ -2846,3 +2847,8 @@ ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *bu
 	return cpu_show_common(dev, attr, buf, X86_BUG_GDS);
 }
 #endif
+
+void __warn_thunk(void)
+{
+	WARN_ONCE(1, "Unpatched return thunk in use. This should not happen!\n");
+}
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 6756025b35ca..39792077f65b 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1856,8 +1856,6 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	/* Init Machine Check Exception if available. */
 	mcheck_cpu_init(c);
 
-	select_idle_routine(c);
-
 #ifdef CONFIG_NUMA
 	numa_add_cpu(smp_processor_id());
 #endif
@@ -1967,6 +1965,7 @@ DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) = {
 	.top_of_stack	= TOP_OF_INIT_STACK,
 };
 EXPORT_PER_CPU_SYMBOL(pcpu_hot);
+EXPORT_PER_CPU_SYMBOL(const_pcpu_hot);
 
 #ifdef CONFIG_X86_64
 DEFINE_PER_CPU_FIRST(struct fixed_percpu_data,
@@ -2278,6 +2277,8 @@ void __init arch_cpu_finalize_init(void)
 {
 	identify_boot_cpu();
 
+	select_idle_routine();
+
 	/*
 	 * identify_boot_cpu() initialized SMT support information, let the
 	 * core code know.