x86/idt: Make IDT init functions static inlines

Move these two functions from kernel/idt.c to include/asm/desc.h:

* init_idt_data()
* idt_init_desc()

These functions are needed to setup IDT entries very early and need to
be called from head64.c. To be usable this early, these functions need
to be compiled without instrumentation and the stack-protector feature.

These features need to be kept enabled for kernel/idt.c, so head64.c
must use its own versions.

[ bp: Take Kees' suggested patch title and add his Rev-by. ]

Signed-off-by: Joerg Roedel <[e-mail]>
Signed-off-by: Borislav Petkov <[e-mail]>
Reviewed-by: Kees Cook <[e-mail]>
Link: https://lkml.kernel.org/r/[e-mail]

arch/x86/include/asm/desc.h

···
 
 void alloc_intr_gate(unsigned int n, const void *addr);
 
+static inline void init_idt_data(struct idt_data *data, unsigned int n,
+				 const void *addr)
+{
+	BUG_ON(n > 0xFF);
+
+	memset(data, 0, sizeof(*data));
+	data->vector	= n;
+	data->addr	= addr;
+	data->segment	= __KERNEL_CS;
+	data->bits.type	= GATE_INTERRUPT;
+	data->bits.p	= 1;
+}
+
+static inline void idt_init_desc(gate_desc *gate, const struct idt_data *d)
+{
+	unsigned long addr = (unsigned long) d->addr;
+
+	gate->offset_low	= (u16) addr;
+	gate->segment		= (u16) d->segment;
+	gate->bits		= d->bits;
+	gate->offset_middle	= (u16) (addr >> 16);
+#ifdef CONFIG_X86_64
+	gate->offset_high	= (u32) (addr >> 32);
+	gate->reserved		= 0;
+#endif
+}
+
 extern unsigned long system_vectors[];
 
 extern void load_current_idt(void);

arch/x86/include/asm/desc_defs.h

···
 			p	: 1;
 } __attribute__((packed));
 
+struct idt_data {
+	unsigned int	vector;
+	unsigned int	segment;
+	struct idt_bits	bits;
+	const void	*addr;
+};
+
 struct gate_struct {
 	u16		offset_low;
 	u16		segment;

arch/x86/kernel/idt.c

···
 #include <asm/desc.h>
 #include <asm/hw_irq.h>
 
-struct idt_data {
-	unsigned int	vector;
-	unsigned int	segment;
-	struct idt_bits	bits;
-	const void	*addr;
-};
-
 #define DPL0		0x0
 #define DPL3		0x3
 
···
 }
 #endif
 
-static inline void idt_init_desc(gate_desc *gate, const struct idt_data *d)
-{
-	unsigned long addr = (unsigned long) d->addr;
-
-	gate->offset_low	= (u16) addr;
-	gate->segment		= (u16) d->segment;
-	gate->bits		= d->bits;
-	gate->offset_middle	= (u16) (addr >> 16);
-#ifdef CONFIG_X86_64
-	gate->offset_high	= (u32) (addr >> 32);
-	gate->reserved		= 0;
-#endif
-}
-
 static __init void
 idt_setup_from_table(gate_desc *idt, const struct idt_data *t, int size, bool sys)
 {
···
 		if (sys)
 			set_bit(t->vector, system_vectors);
 	}
-}
-
-static void init_idt_data(struct idt_data *data, unsigned int n,
-			  const void *addr)
-{
-	BUG_ON(n > 0xFF);
-
-	memset(data, 0, sizeof(*data));
-	data->vector	= n;
-	data->addr	= addr;
-	data->segment	= __KERNEL_CS;
-	data->bits.type	= GATE_INTERRUPT;
-	data->bits.p	= 1;
 }
 
 static __init void set_intr_gate(unsigned int n, const void *addr)