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102 lines
2.5 KiB
Diff
102 lines
2.5 KiB
Diff
From: Felix Fietkau <nbd@openwrt.org>
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Date: Sun, 24 Jan 2016 01:03:51 +0100
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Subject: [PATCH] MIPS: fix cache flushing for highmem pages
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Most cache flush ops were no-op for highmem pages. This led to nasty
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segfaults and (in the case of page_address(page) == NULL) kernel
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crashes.
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Fix this by always flushing highmem pages using kmap/kunmap_atomic
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around the actual cache flush. This might be a bit inefficient, but at
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least it's stable.
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Signed-off-by: Felix Fietkau <nbd@openwrt.org>
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---
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--- a/arch/mips/mm/cache.c
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+++ b/arch/mips/mm/cache.c
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@@ -14,6 +14,7 @@
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <linux/mm.h>
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+#include <linux/highmem.h>
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#include <asm/cacheflush.h>
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#include <asm/processor.h>
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@@ -78,18 +79,29 @@ SYSCALL_DEFINE3(cacheflush, unsigned lon
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return 0;
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}
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+static void
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+flush_highmem_page(struct page *page)
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+{
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+ void *addr = kmap_atomic(page);
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+ flush_data_cache_page((unsigned long)addr);
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+ kunmap_atomic(addr);
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+}
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+
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void __flush_dcache_page(struct page *page)
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{
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struct address_space *mapping = page_mapping(page);
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unsigned long addr;
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- if (PageHighMem(page))
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- return;
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if (mapping && !mapping_mapped(mapping)) {
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SetPageDcacheDirty(page);
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return;
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}
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+ if (PageHighMem(page)) {
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+ flush_highmem_page(page);
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+ return;
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+ }
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+
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/*
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* We could delay the flush for the !page_mapping case too. But that
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* case is for exec env/arg pages and those are %99 certainly going to
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@@ -105,6 +117,11 @@ void __flush_anon_page(struct page *page
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{
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unsigned long addr = (unsigned long) page_address(page);
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+ if (PageHighMem(page)) {
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+ flush_highmem_page(page);
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+ return;
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+ }
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+
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if (pages_do_alias(addr, vmaddr)) {
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if (page_mapped(page) && !Page_dcache_dirty(page)) {
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void *kaddr;
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@@ -123,8 +140,10 @@ void __flush_icache_page(struct vm_area_
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{
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unsigned long addr;
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- if (PageHighMem(page))
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+ if (PageHighMem(page)) {
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+ flush_highmem_page(page);
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return;
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+ }
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addr = (unsigned long) page_address(page);
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flush_data_cache_page(addr);
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@@ -142,12 +161,17 @@ void __update_cache(struct vm_area_struc
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if (unlikely(!pfn_valid(pfn)))
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return;
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page = pfn_to_page(pfn);
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- if (page_mapping(page) && Page_dcache_dirty(page)) {
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+ if (!Page_dcache_dirty(page) || !page_mapping(page))
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+ return;
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+
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+ if (PageHighMem(page)) {
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+ flush_highmem_page(page);
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+ } else {
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addr = (unsigned long) page_address(page);
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if (exec || pages_do_alias(addr, address & PAGE_MASK))
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flush_data_cache_page(addr);
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- ClearPageDcacheDirty(page);
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}
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+ ClearPageDcacheDirty(page);
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}
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unsigned long _page_cachable_default;
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