Merge branch 'x86/entry' into ras/core

to fixup conflicts in arch/x86/kernel/cpu/mce/core.c so MCE specific follow
up patches can be applied without creating a horrible merge conflict
afterwards.

1 files changed, 53 insertions, 0 deletions

diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
new file mode 100644
index 000000000000..4ae66f097101
--- /dev/null
+++ b/arch/x86/include/asm/irq_stack.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_IRQ_STACK_H
+#define _ASM_X86_IRQ_STACK_H
+
+#include <linux/ptrace.h>
+
+#include <asm/processor.h>
+
+#ifdef CONFIG_X86_64
+static __always_inline bool irqstack_active(void)
+{
+	return __this_cpu_read(irq_count) != -1;
+}
+
+void asm_call_on_stack(void *sp, void *func, void *arg);
+
+static __always_inline void __run_on_irqstack(void *func, void *arg)
+{
+	void *tos = __this_cpu_read(hardirq_stack_ptr);
+
+	__this_cpu_add(irq_count, 1);
+	asm_call_on_stack(tos - 8, func, arg);
+	__this_cpu_sub(irq_count, 1);
+}
+
+#else /* CONFIG_X86_64 */
+static inline bool irqstack_active(void) { return false; }
+static inline void __run_on_irqstack(void *func, void *arg) { }
+#endif /* !CONFIG_X86_64 */
+
+static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs)
+{
+	if (IS_ENABLED(CONFIG_X86_32))
+		return false;
+	if (!regs)
+		return !irqstack_active();
+	return !user_mode(regs) && !irqstack_active();
+}
+
+static __always_inline void run_on_irqstack_cond(void *func, void *arg,
+						 struct pt_regs *regs)
+{
+	void (*__func)(void *arg) = func;
+
+	lockdep_assert_irqs_disabled();
+
+	if (irq_needs_irq_stack(regs))
+		__run_on_irqstack(__func, arg);
+	else
+		__func(arg);
+}
+
+#endif