[PATCH for 2.6.22] [8/10] x86: change_page_attr bandaids

From: Andi Kleen
Date: Wed Jun 20 2007 - 06:24:55 EST



- Disable CLFLUSH again; it is still broken. Always do WBINVD.
- Always flush in the i386 case, not only when there are deferred pages.

These are both brute-force inefficient fixes, to be improved
next release cycle.

The changes to i386 are a little more extensive than strictly
needed (some dead code added), but it is more similar to the x86-64 version
now and the dead code will be used soon.

Signed-off-by: Andi Kleen <ak@xxxxxxx>

---
arch/i386/mm/pageattr.c | 30 ++++++++++++++++++------------
arch/x86_64/mm/pageattr.c | 7 ++++---
2 files changed, 22 insertions(+), 15 deletions(-)

Index: linux/arch/i386/mm/pageattr.c
===================================================================
--- linux.orig/arch/i386/mm/pageattr.c
+++ linux/arch/i386/mm/pageattr.c
@@ -68,14 +68,23 @@ static struct page *split_large_page(uns
return base;
}

-static void flush_kernel_map(void *arg)
+static void cache_flush_page(struct page *p)
{
- unsigned long adr = (unsigned long)arg;
+ unsigned long adr = (unsigned long)page_address(p);
+ int i;
+ for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
+ asm volatile("clflush (%0)" :: "r" (adr + i));
+}
+
+static void flush_kernel_map(void *arg)
+{
+ struct list_head *lh = (struct list_head *)arg;
+ struct page *p;

- if (adr && cpu_has_clflush) {
- int i;
- for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size)
- asm volatile("clflush (%0)" :: "r" (adr + i));
+ /* High level code is not ready for clflush yet */
+ if (0 && cpu_has_clflush) {
+ list_for_each_entry (p, lh, lru)
+ cache_flush_page(p);
} else if (boot_cpu_data.x86_model >= 4)
wbinvd();

@@ -181,9 +190,9 @@ __change_page_attr(struct page *page, pg
return 0;
}

-static inline void flush_map(void *adr)
+static inline void flush_map(struct list_head *l)
{
- on_each_cpu(flush_kernel_map, adr, 1, 1);
+ on_each_cpu(flush_kernel_map, l, 1, 1);
}

/*
@@ -225,11 +234,8 @@ void global_flush_tlb(void)
spin_lock_irq(&cpa_lock);
list_replace_init(&df_list, &l);
spin_unlock_irq(&cpa_lock);
- if (!cpu_has_clflush)
- flush_map(NULL);
+ flush_map(&l);
list_for_each_entry_safe(pg, next, &l, lru) {
- if (cpu_has_clflush)
- flush_map(page_address(pg));
__free_page(pg);
}
}
Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86_64/mm/pageattr.c
+++ linux/arch/x86_64/mm/pageattr.c
@@ -74,10 +74,11 @@ static void flush_kernel_map(void *arg)
struct page *pg;

/* When clflush is available always use it because it is
- much cheaper than WBINVD */
- if (!cpu_has_clflush)
+ much cheaper than WBINVD. Disable clflush for now because
+ the high level code is not ready yet */
+ if (1 || !cpu_has_clflush)
asm volatile("wbinvd" ::: "memory");
- list_for_each_entry(pg, l, lru) {
+ else list_for_each_entry(pg, l, lru) {
void *adr = page_address(pg);
if (cpu_has_clflush)
cache_flush_page(adr);
-
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