[tip:x86/irq] x86/irq/64: Use cpu entry area instead of orig_ist

[tip-bot for Thomas Gleixner]

Commit-ID:  bf5882abab773afd1277415e2f826b21de28f30d
Gitweb:     https://git.kernel.org/tip/bf5882abab773afd1277415e2f826b21de28f30d
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Sun, 14 Apr 2019 17:59:51 +0200
Committer:  Borislav Petkov <bp@xxxxxxx>
CommitDate: Wed, 17 Apr 2019 13:02:48 +0200

x86/irq/64: Use cpu entry area instead of orig_ist

The orig_ist[] array is a shadow copy of the IST array in the TSS. The
reason why it exists is that older kernels used two TSS variants with
different pointers into the debug stack. orig_ist[] contains the real
starting points.

There is no point anymore to do so because the same information can be
retrieved using the base address of the cpu entry area mapping and the
offsets of the various exception stacks.

No functional change. Preparation for removing orig_ist.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Nicolai Stange <nstange@xxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20190414160144.885741626@xxxxxxxxxxxxx
---
 arch/x86/kernel/irq_64.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 182e8b245e06..7eb6f8d11bfd 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -18,6 +18,8 @@
 #include <linux/uaccess.h>
 #include <linux/smp.h>
 #include <linux/sched/task_stack.h>
+
+#include <asm/cpu_entry_area.h>
 #include <asm/io_apic.h>
 #include <asm/apic.h>
 
@@ -43,10 +45,9 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 {
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
 #define STACK_MARGIN	128
-	struct orig_ist *oist;
-	u64 irq_stack_top, irq_stack_bottom;
-	u64 estack_top, estack_bottom;
+	u64 irq_stack_top, irq_stack_bottom, estack_top, estack_bottom;
 	u64 curbase = (u64)task_stack_page(current);
+	struct cea_exception_stacks *estacks;
 
 	if (user_mode(regs))
 		return;
@@ -60,9 +61,9 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 	if (regs->sp >= irq_stack_bottom && regs->sp <= irq_stack_top)
 		return;
 
-	oist = this_cpu_ptr(&orig_ist);
-	estack_top = (u64)oist->ist[ESTACK_DB];
-	estack_bottom = estack_top - DEBUG_STKSZ + STACK_MARGIN;
+	estacks = __this_cpu_read(cea_exception_stacks);
+	estack_top = CEA_ESTACK_TOP(estacks, DB);
+	estack_bottom = CEA_ESTACK_BOT(estacks, DB) + STACK_MARGIN;
 	if (regs->sp >= estack_bottom && regs->sp <= estack_top)
 		return;