From: Zwane Mwaikambo <zwane@linuxpower.ca>
The 4/4 code right now is setup for 8k stacks, this patch should allow for
arbitrary stack sizes. Some parts are rather ugly (e.g. STACK_PAGE_COUNT)
so (abusive too) comments are welcome.
I've tested it with 4k,8k and 16k stacks on UP and SMP, but i believe it
diff -upN reference/arch/i386/kernel/entry_trampoline.c current/arch/i386/kernel/entry_trampoline.c
--- reference/arch/i386/kernel/entry_trampoline.c 2004-05-01 15:03:30.000000000 -0700
+++ current/arch/i386/kernel/entry_trampoline.c 2004-05-01 15:05:36.000000000 -0700
@@ -21,7 +21,9 @@ extern char __entry_tramp_start, __entry
void __init init_entry_mappings(void)
{
#ifdef CONFIG_X86_HIGH_ENTRY
+
void *tramp;
+ int p;
/*
* We need a high IDT and GDT for the 4G/4G split:
@@ -37,7 +39,7 @@ void __init init_entry_mappings(void)
/*
* Virtual kernel stack:
*/
- BUG_ON(__kmap_atomic_vaddr(KM_VSTACK0) & (THREAD_SIZE-1));
+ BUG_ON(__kmap_atomic_vaddr(KM_VSTACK_TOP) & (THREAD_SIZE-1));
BUG_ON(sizeof(struct desc_struct)*NR_CPUS*GDT_ENTRIES > 2*PAGE_SIZE);
BUG_ON((unsigned int)&__entry_tramp_end - (unsigned int)&__entry_tramp_start > 2*PAGE_SIZE);
@@ -45,15 +47,15 @@ void __init init_entry_mappings(void)
* set up the initial thread's virtual stack related
* fields:
*/
- current->thread.stack_page0 = virt_to_page((char *)current->thread_info);
- current->thread.stack_page1 = virt_to_page((char *)current->thread_info + PAGE_SIZE);
- current->thread_info->virtual_stack = (void *)__kmap_atomic_vaddr(KM_VSTACK0);
-
- __kunmap_atomic_type(KM_VSTACK0);
- __kunmap_atomic_type(KM_VSTACK1);
- __kmap_atomic(current->thread.stack_page0, KM_VSTACK0);
- __kmap_atomic(current->thread.stack_page1, KM_VSTACK1);
+ for (p = 0; p < ARRAY_SIZE(current->thread.stack_page); p++)
+ current->thread.stack_page[p] = virt_to_page((char *)current->thread_info + (p*PAGE_SIZE));
+
+ current->thread_info->virtual_stack = (void *)__kmap_atomic_vaddr(KM_VSTACK_TOP);
+ for (p = 0; p < ARRAY_SIZE(current->thread.stack_page); p++) {
+ __kunmap_atomic_type(KM_VSTACK_TOP-p);
+ __kmap_atomic(current->thread.stack_page[p], KM_VSTACK_TOP-p);
+ }
#endif
current->thread_info->real_stack = (void *)current->thread_info;
current->thread_info->user_pgd = NULL;
diff -upN reference/arch/i386/kernel/process.c current/arch/i386/kernel/process.c
--- reference/arch/i386/kernel/process.c 2004-05-01 15:03:30.000000000 -0700
+++ current/arch/i386/kernel/process.c 2004-05-01 15:05:36.000000000 -0700
@@ -345,7 +345,7 @@ int copy_thread(int nr, unsigned long cl
{
struct pt_regs * childregs;
struct task_struct *tsk;
- int err;
+ int err, i;
childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
struct_cpy(childregs, regs);
@@ -360,10 +360,11 @@ int copy_thread(int nr, unsigned long cl
* get the two stack pages, for the virtual stack.
*
* IMPORTANT: this code relies on the fact that the task
- * structure is an 8K aligned piece of physical memory.
+ * structure is an THREAD_SIZE aligned piece of physical memory.
*/
- p->thread.stack_page0 = virt_to_page((unsigned long)p->thread_info);
- p->thread.stack_page1 = virt_to_page((unsigned long)p->thread_info + PAGE_SIZE);
+ for (i = 0; i < ARRAY_SIZE(p->thread.stack_page); i++)
+ p->thread.stack_page[i] =
+ virt_to_page((unsigned long)p->thread_info + (i*PAGE_SIZE));
p->thread.eip = (unsigned long) ret_from_fork;
p->thread_info->real_stack = p->thread_info;
@@ -519,22 +520,23 @@ struct task_struct fastcall * __switch_t
__unlazy_fpu(prev_p);
#ifdef CONFIG_X86_HIGH_ENTRY
+{
+ int i;
/*
* Set the ptes of the virtual stack. (NOTE: a one-page TLB flush is
* needed because otherwise NMIs could interrupt the
* user-return code with a virtual stack and stale TLBs.)
*/
- __kunmap_atomic_type(KM_VSTACK0);
- __kunmap_atomic_type(KM_VSTACK1);
- __kmap_atomic(next->stack_page0, KM_VSTACK0);
- __kmap_atomic(next->stack_page1, KM_VSTACK1);
-
+ for (i = 0; i < ARRAY_SIZE(next->stack_page); i++) {
+ __kunmap_atomic_type(KM_VSTACK_TOP-i);
+ __kmap_atomic(next->stack_page[i], KM_VSTACK_TOP-i);
+ }
/*
* NOTE: here we rely on the task being the stack as well
*/
next_p->thread_info->virtual_stack =
- (void *)__kmap_atomic_vaddr(KM_VSTACK0);
-
+ (void *)__kmap_atomic_vaddr(KM_VSTACK_TOP);
+}
#if defined(CONFIG_PREEMPT) && defined(CONFIG_SMP)
/*
* If next was preempted on entry from userspace to kernel,
diff -upN reference/include/asm-i386/fixmap.h current/include/asm-i386/fixmap.h
--- reference/include/asm-i386/fixmap.h 2004-05-01 15:03:30.000000000 -0700
+++ current/include/asm-i386/fixmap.h 2004-05-01 15:05:36.000000000 -0700
@@ -115,10 +115,10 @@ extern void __set_fixmap (enum fixed_add
* Leave one empty page between vmalloc'ed areas and
* the start of the fixmap.
*
- * IMPORTANT: dont change FIXADDR_TOP without adjusting KM_VSTACK0
- * and KM_VSTACK1 so that the virtual stack is 8K aligned.
+ * IMPORTANT: we have to align FIXADDR_TOP so that the virtual stack
+ * is THREAD_SIZE aligned.
*/
-#define FIXADDR_TOP (0xffffe000UL)
+#define FIXADDR_TOP (0xffffe000UL & ~(THREAD_SIZE-1))
#define __FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
diff -upN reference/include/asm-i386/kmap_types.h current/include/asm-i386/kmap_types.h
--- reference/include/asm-i386/kmap_types.h 2004-05-01 15:03:30.000000000 -0700
+++ current/include/asm-i386/kmap_types.h 2004-05-01 15:05:36.000000000 -0700
@@ -2,15 +2,16 @@
#define _ASM_KMAP_TYPES_H
#include <linux/config.h>
+#include <linux/thread_info.h>
enum km_type {
/*
- * IMPORTANT: don't move these 3 entries, and only add entries in
- * pairs: the 4G/4G virtual stack must be 8K aligned on each cpu.
+ * IMPORTANT: don't move these 3 entries, be wary when adding entries,
+ * the 4G/4G virtual stack must be THREAD_SIZE aligned on each cpu.
*/
KM_BOUNCE_READ,
- KM_VSTACK1,
- KM_VSTACK0,
+ KM_VSTACK_BASE,
+ KM_VSTACK_TOP = KM_VSTACK_BASE + STACK_PAGE_COUNT-1,
KM_LDT_PAGE15,
KM_LDT_PAGE0 = KM_LDT_PAGE15 + 16-1,
@@ -30,8 +31,8 @@ enum km_type {
KM_SOFTIRQ1,
KM_FILLER,
/*
- * Add new entries in pairs:
- * the 4G/4G virtual stack must be 8K aligned on each cpu.
+ * Be wary when adding entries:
+ * the 4G/4G virtual stack must be THREAD_SIZE aligned on each cpu.
*/
KM_TYPE_NR
};
diff -upN reference/include/asm-i386/processor.h current/include/asm-i386/processor.h
--- reference/include/asm-i386/processor.h 2004-05-01 15:03:30.000000000 -0700
+++ current/include/asm-i386/processor.h 2004-05-01 15:05:36.000000000 -0700
@@ -400,10 +400,16 @@ struct tss_struct {
#define ARCH_MIN_TASKALIGN 16
+#ifdef CONFIG_4KSTACKS
+#define STACK_PAGE_COUNT (4096/PAGE_SIZE)
+#else
+#define STACK_PAGE_COUNT (8192/PAGE_SIZE) /* THREAD_SIZE/PAGE_SIZE */
+#endif
+
struct thread_struct {
/* cached TLS descriptors. */
struct desc_struct tls_array[GDT_ENTRY_TLS_ENTRIES];
- void *stack_page0, *stack_page1;
+ void *stack_page[STACK_PAGE_COUNT];
unsigned long esp0;
unsigned long sysenter_cs;
unsigned long eip;
diff -upN reference/include/asm-i386/thread_info.h current/include/asm-i386/thread_info.h
--- reference/include/asm-i386/thread_info.h 2004-05-01 15:03:30.000000000 -0700
+++ current/include/asm-i386/thread_info.h 2004-05-01 15:05:36.000000000 -0700
@@ -49,8 +49,10 @@ struct thread_info {
#endif
#define PREEMPT_ACTIVE 0x4000000
+
+/* if you change THREAD_SIZE here, don't forget to change STACK_PAGE_COUNT */
#ifdef CONFIG_4KSTACKS
-#define THREAD_SIZE (4096)
+#define THREAD_SIZE (4096)
#else
#define THREAD_SIZE (8192)
#endif