linux-kernel - [PATCH 04/17] x86-64: Convert exception stacks to per-cpu

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Date:	Fri, 16 Jan 2009 09:16:23 -0500
From:	Brian Gerst <brgerst@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Brian Gerst <brgerst@...il.com>
Subject: [PATCH 04/17] x86-64: Convert exception stacks to per-cpu

Move the exception stacks to per-cpu, removing specific allocation code.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/kernel/cpu/common.c |   23 ++++++++---------------
 1 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 5ddbca0..70ce998 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -908,8 +908,9 @@ void __cpuinit pda_init(int cpu)
 	}
 }
 
-static char boot_exception_stacks[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ +
-				  DEBUG_STKSZ] __page_aligned_bss;
+static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks
+	[(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ])
+	__aligned(PAGE_SIZE);
 
 extern asmlinkage void ignore_sysret(void);
 
@@ -967,15 +968,12 @@ void __cpuinit cpu_init(void)
 	struct tss_struct *t = &per_cpu(init_tss, cpu);
 	struct orig_ist *orig_ist = &per_cpu(orig_ist, cpu);
 	unsigned long v;
-	char *estacks = NULL;
 	struct task_struct *me;
 	int i;
 
 	/* CPU 0 is initialised in head64.c */
 	if (cpu != 0)
 		pda_init(cpu);
-	else
-		estacks = boot_exception_stacks;
 
 	me = current;
 
@@ -1009,18 +1007,13 @@ void __cpuinit cpu_init(void)
 	 * set up and load the per-CPU TSS
 	 */
 	if (!orig_ist->ist[0]) {
-		static const unsigned int order[N_EXCEPTION_STACKS] = {
-		  [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER,
-		  [DEBUG_STACK - 1] = DEBUG_STACK_ORDER
+		static const unsigned int sizes[N_EXCEPTION_STACKS] = {
+		  [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STKSZ,
+		  [DEBUG_STACK - 1] = DEBUG_STKSZ
 		};
+		char *estacks = per_cpu(exception_stacks, cpu);
 		for (v = 0; v < N_EXCEPTION_STACKS; v++) {
-			if (cpu) {
-				estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]);
-				if (!estacks)
-					panic("Cannot allocate exception "
-					      "stack %ld %d\n", v, cpu);
-			}
-			estacks += PAGE_SIZE << order[v];
+			estacks += sizes[v];
 			orig_ist->ist[v] = t->x86_tss.ist[v] =
 					(unsigned long)estacks;
 		}
-- 
1.6.1.rc1

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