linux-kernel - [tip:x86/irq] x86/irq/64: Sanitize the top/bottom confusion

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Date:   Wed, 17 Apr 2019 07:04:39 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     x86@...nel.org, bp@...e.de, luto@...nel.org,
        linux-kernel@...r.kernel.org, sean.j.christopherson@...el.com,
        nstange@...e.de, mingo@...hat.com, tglx@...utronix.de,
        hpa@...or.com, jpoimboe@...hat.com, mingo@...nel.org
Subject: [tip:x86/irq] x86/irq/64: Sanitize the top/bottom confusion

Commit-ID:  df835e7083bee33e98635aca26b39b63ebc6cca7
Gitweb:     https://git.kernel.org/tip/df835e7083bee33e98635aca26b39b63ebc6cca7
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 14 Apr 2019 17:59:41 +0200
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Wed, 17 Apr 2019 12:34:49 +0200

x86/irq/64: Sanitize the top/bottom confusion

On x86, stacks go top to bottom, but the stack overflow check uses it
the other way round, which is just confusing. Clean it up and sanitize
the warning string a bit.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Nicolai Stange <nstange@...e.de>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/20190414160143.961241397@linutronix.de
---
 arch/x86/kernel/irq_64.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index f6dcc8fea5c0..cf200466d5c8 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -42,7 +42,7 @@ int sysctl_panic_on_stackoverflow;
 static inline void stack_overflow_check(struct pt_regs *regs)
 {
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
-#define STACK_TOP_MARGIN	128
+#define STACK_MARGIN	128
 	struct orig_ist *oist;
 	u64 irq_stack_top, irq_stack_bottom;
 	u64 estack_top, estack_bottom;
@@ -51,25 +51,25 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 	if (user_mode(regs))
 		return;
 
-	if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
+	if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_MARGIN &&
 	    regs->sp <= curbase + THREAD_SIZE)
 		return;
 
-	irq_stack_bottom = (u64)__this_cpu_read(irq_stack_ptr);
-	irq_stack_top = irq_stack_bottom - IRQ_STACK_SIZE + STACK_TOP_MARGIN;
-	if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
+	irq_stack_top = (u64)__this_cpu_read(irq_stack_ptr);
+	irq_stack_bottom = irq_stack_top - IRQ_STACK_SIZE + STACK_MARGIN;
+	if (regs->sp >= irq_stack_bottom && regs->sp <= irq_stack_top)
 		return;
 
 	oist = this_cpu_ptr(&orig_ist);
-	estack_bottom = (u64)oist->ist[DEBUG_STACK];
-	estack_top = estack_bottom - DEBUG_STKSZ + STACK_TOP_MARGIN;
-	if (regs->sp >= estack_top && regs->sp <= estack_bottom)
+	estack_top = (u64)oist->ist[DEBUG_STACK];
+	estack_bottom = estack_top - DEBUG_STKSZ + STACK_MARGIN;
+	if (regs->sp >= estack_bottom && regs->sp <= estack_top)
 		return;
 
-	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx,ip:%pF)\n",
+	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx, irq stack:%Lx-%Lx, exception stack: %Lx-%Lx, ip:%pF)\n",
 		current->comm, curbase, regs->sp,
-		irq_stack_top, irq_stack_bottom,
-		estack_top, estack_bottom, (void *)regs->ip);
+		irq_stack_bottom, irq_stack_top,
+		estack_bottom, estack_top, (void *)regs->ip);
 
 	if (sysctl_panic_on_stackoverflow)
 		panic("low stack detected by irq handler - check messages\n");