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authorJosh Poimboeuf <jpoimboe@redhat.com>2016-08-18 10:59:08 -0500
committerIngo Molnar <mingo@kernel.org>2016-08-18 18:41:33 +0200
commit4950d6d48a0c43cc61d0bbb76fb10e0214b79c66 (patch)
treed73a8e4b7c0670f0183862261808f6abb23ae36e /arch
parent8b927d734122f3021c5999aaeffaa2a36ab224c2 (diff)
download96b-common-4950d6d48a0c43cc61d0bbb76fb10e0214b79c66.tar.gz
x86/dumpstack: Remove 64-byte gap at end of irq stack
There has been a 64-byte gap at the end of the irq stack for at least 12 years. It predates git history, and I can't find any good reason for it. Remove it. What's the worst that could happen? Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nilay Vaish <nilayvaish@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/14f9281c5475cc44af95945ea7546bff2e3836db.1471535549.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/common.c2
-rw-r--r--arch/x86/kernel/dumpstack_64.c9
-rw-r--r--arch/x86/kernel/setup_percpu.c2
3 files changed, 5 insertions, 8 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 809eda03c527..6ef55e83fb8a 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1281,7 +1281,7 @@ DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
EXPORT_PER_CPU_SYMBOL(current_task);
DEFINE_PER_CPU(char *, irq_stack_ptr) =
- init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE - 64;
+ init_per_cpu_var(irq_stack_union.irq_stack) + IRQ_STACK_SIZE;
DEFINE_PER_CPU(unsigned int, irq_count) __visible = -1;
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index daf9f6321856..066eb5c77fd6 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -103,9 +103,6 @@ in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
return (stack >= irq_stack && stack < irq_stack_end);
}
-static const unsigned long irq_stack_size =
- (IRQ_STACK_SIZE - 64) / sizeof(unsigned long);
-
enum stack_type {
STACK_IS_UNKNOWN,
STACK_IS_NORMAL,
@@ -133,7 +130,7 @@ analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
return STACK_IS_NORMAL;
*stack_end = irq_stack;
- irq_stack = irq_stack - irq_stack_size;
+ irq_stack -= (IRQ_STACK_SIZE / sizeof(long));
if (in_irq_stack(stack, irq_stack, *stack_end))
return STACK_IS_IRQ;
@@ -256,8 +253,8 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
preempt_disable();
cpu = smp_processor_id();
- irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
- irq_stack = (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
+ irq_stack_end = (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
+ irq_stack = irq_stack_end - (IRQ_STACK_SIZE / sizeof(long));
/*
* Debugging aid: "show_stack(NULL, NULL);" prints the
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 7a40e068302d..d182799c4264 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -246,7 +246,7 @@ void __init setup_per_cpu_areas(void)
#ifdef CONFIG_X86_64
per_cpu(irq_stack_ptr, cpu) =
per_cpu(irq_stack_union.irq_stack, cpu) +
- IRQ_STACK_SIZE - 64;
+ IRQ_STACK_SIZE;
#endif
#ifdef CONFIG_NUMA
per_cpu(x86_cpu_to_node_map, cpu) =