Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 229 insertions, 0 deletions

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
new file mode 100644
index 0000000000..998a08f17e
--- /dev/null
+++ b/arch/x86/kernel/fpu/init.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * x86 FPU boot time init code:
+ */
+#include <asm/fpu/api.h>
+#include <asm/tlbflush.h>
+#include <asm/setup.h>
+
+#include <linux/sched.h>
+#include <linux/sched/task.h>
+#include <linux/init.h>
+
+#include "internal.h"
+#include "legacy.h"
+#include "xstate.h"
+
+/*
+ * Initialize the registers found in all CPUs, CR0 and CR4:
+ */
+static void fpu__init_cpu_generic(void)
+{
+	unsigned long cr0;
+	unsigned long cr4_mask = 0;
+
+	if (boot_cpu_has(X86_FEATURE_FXSR))
+		cr4_mask |= X86_CR4_OSFXSR;
+	if (boot_cpu_has(X86_FEATURE_XMM))
+		cr4_mask |= X86_CR4_OSXMMEXCPT;
+	if (cr4_mask)
+		cr4_set_bits(cr4_mask);
+
+	cr0 = read_cr0();
+	cr0 &= ~(X86_CR0_TS|X86_CR0_EM); /* clear TS and EM */
+	if (!boot_cpu_has(X86_FEATURE_FPU))
+		cr0 |= X86_CR0_EM;
+	write_cr0(cr0);
+
+	/* Flush out any pending x87 state: */
+#ifdef CONFIG_MATH_EMULATION
+	if (!boot_cpu_has(X86_FEATURE_FPU))
+		fpstate_init_soft(&current->thread.fpu.fpstate->regs.soft);
+	else
+#endif
+		asm volatile ("fninit");
+}
+
+/*
+ * Enable all supported FPU features. Called when a CPU is brought online:
+ */
+void fpu__init_cpu(void)
+{
+	fpu__init_cpu_generic();
+	fpu__init_cpu_xstate();
+}
+
+static bool __init fpu__probe_without_cpuid(void)
+{
+	unsigned long cr0;
+	u16 fsw, fcw;
+
+	fsw = fcw = 0xffff;
+
+	cr0 = read_cr0();
+	cr0 &= ~(X86_CR0_TS | X86_CR0_EM);
+	write_cr0(cr0);
+
+	asm volatile("fninit ; fnstsw %0 ; fnstcw %1" : "+m" (fsw), "+m" (fcw));
+
+	pr_info("x86/fpu: Probing for FPU: FSW=0x%04hx FCW=0x%04hx\n", fsw, fcw);
+
+	return fsw == 0 && (fcw & 0x103f) == 0x003f;
+}
+
+static void __init fpu__init_system_early_generic(void)
+{
+	if (!boot_cpu_has(X86_FEATURE_CPUID) &&
+	    !test_bit(X86_FEATURE_FPU, (unsigned long *)cpu_caps_cleared)) {
+		if (fpu__probe_without_cpuid())
+			setup_force_cpu_cap(X86_FEATURE_FPU);
+		else
+			setup_clear_cpu_cap(X86_FEATURE_FPU);
+	}
+
+#ifndef CONFIG_MATH_EMULATION
+	if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_FPU)) {
+		pr_emerg("x86/fpu: Giving up, no FPU found and no math emulation present\n");
+		for (;;)
+			asm volatile("hlt");
+	}
+#endif
+}
+
+/*
+ * Boot time FPU feature detection code:
+ */
+unsigned int mxcsr_feature_mask __ro_after_init = 0xffffffffu;
+EXPORT_SYMBOL_GPL(mxcsr_feature_mask);
+
+static void __init fpu__init_system_mxcsr(void)
+{
+	unsigned int mask = 0;
+
+	if (boot_cpu_has(X86_FEATURE_FXSR)) {
+		/* Static because GCC does not get 16-byte stack alignment right: */
+		static struct fxregs_state fxregs __initdata;
+
+		asm volatile("fxsave %0" : "+m" (fxregs));
+
+		mask = fxregs.mxcsr_mask;
+
+		/*
+		 * If zero then use the default features mask,
+		 * which has all features set, except the
+		 * denormals-are-zero feature bit:
+		 */
+		if (mask == 0)
+			mask = 0x0000ffbf;
+	}
+	mxcsr_feature_mask &= mask;
+}
+
+/*
+ * Once per bootup FPU initialization sequences that will run on most x86 CPUs:
+ */
+static void __init fpu__init_system_generic(void)
+{
+	/*
+	 * Set up the legacy init FPU context. Will be updated when the
+	 * CPU supports XSAVE[S].
+	 */
+	fpstate_init_user(&init_fpstate);
+
+	fpu__init_system_mxcsr();
+}
+
+/*
+ * Enforce that 'MEMBER' is the last field of 'TYPE'.
+ *
+ * Align the computed size with alignment of the TYPE,
+ * because that's how C aligns structs.
+ */
+#define CHECK_MEMBER_AT_END_OF(TYPE, MEMBER) \
+	BUILD_BUG_ON(sizeof(TYPE) !=         \
+		     ALIGN(offsetofend(TYPE, MEMBER), _Alignof(TYPE)))
+
+/*
+ * We append the 'struct fpu' to the task_struct:
+ */
+static void __init fpu__init_task_struct_size(void)
+{
+	int task_size = sizeof(struct task_struct);
+
+	/*
+	 * Subtract off the static size of the register state.
+	 * It potentially has a bunch of padding.
+	 */
+	task_size -= sizeof(current->thread.fpu.__fpstate.regs);
+
+	/*
+	 * Add back the dynamically-calculated register state
+	 * size.
+	 */
+	task_size += fpu_kernel_cfg.default_size;
+
+	/*
+	 * We dynamically size 'struct fpu', so we require that
+	 * it be at the end of 'thread_struct' and that
+	 * 'thread_struct' be at the end of 'task_struct'.  If
+	 * you hit a compile error here, check the structure to
+	 * see if something got added to the end.
+	 */
+	CHECK_MEMBER_AT_END_OF(struct fpu, __fpstate);
+	CHECK_MEMBER_AT_END_OF(struct thread_struct, fpu);
+	CHECK_MEMBER_AT_END_OF(struct task_struct, thread);
+
+	arch_task_struct_size = task_size;
+}
+
+/*
+ * Set up the user and kernel xstate sizes based on the legacy FPU context size.
+ *
+ * We set this up first, and later it will be overwritten by
+ * fpu__init_system_xstate() if the CPU knows about xstates.
+ */
+static void __init fpu__init_system_xstate_size_legacy(void)
+{
+	unsigned int size;
+
+	/*
+	 * Note that the size configuration might be overwritten later
+	 * during fpu__init_system_xstate().
+	 */
+	if (!cpu_feature_enabled(X86_FEATURE_FPU)) {
+		size = sizeof(struct swregs_state);
+	} else if (cpu_feature_enabled(X86_FEATURE_FXSR)) {
+		size = sizeof(struct fxregs_state);
+		fpu_user_cfg.legacy_features = XFEATURE_MASK_FPSSE;
+	} else {
+		size = sizeof(struct fregs_state);
+		fpu_user_cfg.legacy_features = XFEATURE_MASK_FP;
+	}
+
+	fpu_kernel_cfg.max_size = size;
+	fpu_kernel_cfg.default_size = size;
+	fpu_user_cfg.max_size = size;
+	fpu_user_cfg.default_size = size;
+	fpstate_reset(&current->thread.fpu);
+}
+
+/*
+ * Called on the boot CPU once per system bootup, to set up the initial
+ * FPU state that is later cloned into all processes:
+ */
+void __init fpu__init_system(void)
+{
+	fpstate_reset(&current->thread.fpu);
+	fpu__init_system_early_generic();
+
+	/*
+	 * The FPU has to be operational for some of the
+	 * later FPU init activities:
+	 */
+	fpu__init_cpu();
+
+	fpu__init_system_generic();
+	fpu__init_system_xstate_size_legacy();
+	fpu__init_system_xstate(fpu_kernel_cfg.max_size);
+	fpu__init_task_struct_size();
+}