traps: x86: converge trap_init functions

- set_system_gate on i386 is really set_system_trap_gate
 - set_system_gate on x86_64 is really set_system_intr_gate
 - ist=0 means no special stack switch is done:
	- introduce STACKFAULT_STACK, DOUBLEFAULT_STACK, NMI_STACK,
		DEBUG_STACK and MCE_STACK as on x86_64.
	- use the _ist variants with XXX_STACK set to zero
 - remove set_system_gate

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

traps: x86: correct copy/paste bug: a trap is a GATE_TRAP

Fix copy/paste/forgot-to-edit bug in desc.h.

Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/traps_32.c

@@ -847,10 +847,12 @@ void __init trap_init(void)
 #endif
 
 	set_intr_gate(0, &divide_error);
-	set_intr_gate(1, &debug);
-	set_intr_gate(2, &nmi);
-	set_system_intr_gate(3, &int3); /* int3 can be called from all */
-	set_system_intr_gate(4, &overflow); /* int4 can be called from all */
+	set_intr_gate_ist(1, &debug, DEBUG_STACK);
+	set_intr_gate_ist(2, &nmi, NMI_STACK);
+	/* int3 can be called from all */
+	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
+	/* int4 can be called from all */
+	set_system_intr_gate(4, &overflow);
 	set_intr_gate(5, &bounds);
 	set_intr_gate(6, &invalid_op);
 	set_intr_gate(7, &device_not_available);
@@ -858,14 +860,14 @@ void __init trap_init(void)
 	set_intr_gate(9, &coprocessor_segment_overrun);
 	set_intr_gate(10, &invalid_TSS);
 	set_intr_gate(11, &segment_not_present);
-	set_intr_gate(12, &stack_segment);
+	set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK);
 	set_intr_gate(13, &general_protection);
 	set_intr_gate(14, &page_fault);
 	set_intr_gate(15, &spurious_interrupt_bug);
 	set_intr_gate(16, &coprocessor_error);
 	set_intr_gate(17, &alignment_check);
 #ifdef CONFIG_X86_MCE
-	set_intr_gate(18, &machine_check);
+	set_intr_gate_ist(18, &machine_check, MCE_STACK);
 #endif
 	set_intr_gate(19, &simd_coprocessor_error);
 
@@ -881,7 +883,7 @@ void __init trap_init(void)
 		printk("done.\n");
 	}
 
-	set_system_gate(SYSCALL_VECTOR, &system_call);
+	set_system_trap_gate(SYSCALL_VECTOR, &system_call);
 
 	/* Reserve all the builtin and the syscall vector: */
 	for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)

arch/x86/kernel/traps_64.c

@@ -647,9 +647,9 @@ void __init trap_init(void)
 	set_intr_gate_ist(1, &debug, DEBUG_STACK);
 	set_intr_gate_ist(2, &nmi, NMI_STACK);
 	/* int3 can be called from all */
-	set_system_gate_ist(3, &int3, DEBUG_STACK);
+	set_system_intr_gate_ist(3, &int3, DEBUG_STACK);
 	/* int4 can be called from all */
-	set_system_gate(4, &overflow);
+	set_system_intr_gate(4, &overflow);
 	set_intr_gate(5, &bounds);
 	set_intr_gate(6, &invalid_op);
 	set_intr_gate(7, &device_not_available);
@@ -669,7 +669,7 @@ void __init trap_init(void)
 	set_intr_gate(19, &simd_coprocessor_error);
 
 #ifdef CONFIG_IA32_EMULATION
-	set_system_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
+	set_system_intr_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
 #endif
 	/*
 	 * Should be a barrier for any external CPU state:

include/asm-x86/desc.h

@@ -351,22 +351,18 @@ static inline void set_system_intr_gate(unsigned int n, void *addr)
 	_set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
 }
 
+static inline void set_system_trap_gate(unsigned int n, void *addr)
+{
+	BUG_ON((unsigned)n > 0xFF);
+	_set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
+}
+
 static inline void set_trap_gate(unsigned int n, void *addr)
 {
 	BUG_ON((unsigned)n > 0xFF);
 	_set_gate(n, GATE_TRAP, addr, 0, 0, __KERNEL_CS);
 }
 
-static inline void set_system_gate(unsigned int n, void *addr)
-{
-	BUG_ON((unsigned)n > 0xFF);
-#ifdef CONFIG_X86_32
-	_set_gate(n, GATE_TRAP, addr, 0x3, 0, __KERNEL_CS);
-#else
-	_set_gate(n, GATE_INTERRUPT, addr, 0x3, 0, __KERNEL_CS);
-#endif
-}
-
 static inline void set_task_gate(unsigned int n, unsigned int gdt_entry)
 {
 	BUG_ON((unsigned)n > 0xFF);
@@ -379,7 +375,7 @@ static inline void set_intr_gate_ist(int n, void *addr, unsigned ist)
 	_set_gate(n, GATE_INTERRUPT, addr, 0, ist, __KERNEL_CS);
 }
 
-static inline void set_system_gate_ist(int n, void *addr, unsigned ist)
+static inline void set_system_intr_gate_ist(int n, void *addr, unsigned ist)
 {
 	BUG_ON((unsigned)n > 0xFF);
 	_set_gate(n, GATE_INTERRUPT, addr, 0x3, ist, __KERNEL_CS);

include/asm-x86/page_32.h

@@ -20,6 +20,12 @@
 #endif
 #define THREAD_SIZE 	(PAGE_SIZE << THREAD_ORDER)
 
+#define STACKFAULT_STACK 0
+#define DOUBLEFAULT_STACK 1
+#define NMI_STACK 0
+#define DEBUG_STACK 0
+#define MCE_STACK 0
+#define N_EXCEPTION_STACKS 1
 
 #ifdef CONFIG_X86_PAE
 /* 44=32+12, the limit we can fit into an unsigned long pfn */