kernel: fix MIPS highmem breakage

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
SVN-Revision: 48468

diff --git a/target/linux/generic/patches-4.3/101-MIPS-fix-cache-flushing-for-highmem-pages.patch b/target/linux/generic/patches-4.3/101-MIPS-fix-cache-flushing-for-highmem-pages.patch
new file mode 100644 (file)
index 0000000..d7220af
--- /dev/null
+++ b/target/linux/generic/patches-4.3/101-MIPS-fix-cache-flushing-for-highmem-pages.patch
@@ -0,0 +1,95 @@
+From: Felix Fietkau <nbd@openwrt.org>
+Date: Sun, 24 Jan 2016 01:03:51 +0100
+Subject: [PATCH] MIPS: fix cache flushing for highmem pages
+
+Most cache flush ops were no-op for highmem pages. This led to nasty
+segfaults and (in the case of page_address(page) == NULL) kernel
+crashes.
+
+Fix this by always flushing highmem pages using kmap/kunmap_atomic
+around the actual cache flush. This might be a bit inefficient, but at
+least it's stable.
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/arch/mips/mm/cache.c
++++ b/arch/mips/mm/cache.c
+@@ -14,6 +14,7 @@
+ #include <linux/sched.h>
+ #include <linux/syscalls.h>
+ #include <linux/mm.h>
++#include <linux/highmem.h>
+ 
+ #include <asm/cacheflush.h>
+ #include <asm/processor.h>
+@@ -78,18 +79,29 @@ SYSCALL_DEFINE3(cacheflush, unsigned lon
+       return 0;
+ }
+ 
++static void
++flush_highmem_page(struct page *page)
++{
++      void *addr = kmap_atomic(page);
++      flush_data_cache_page((unsigned long)addr);
++      kunmap_atomic(addr);
++}
++
+ void __flush_dcache_page(struct page *page)
+ {
+       struct address_space *mapping = page_mapping(page);
+       unsigned long addr;
+ 
+-      if (PageHighMem(page))
+-              return;
+       if (mapping && !mapping_mapped(mapping)) {
+               SetPageDcacheDirty(page);
+               return;
+       }
+ 
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++              return;
++      }
++
+       /*
+        * We could delay the flush for the !page_mapping case too.  But that
+        * case is for exec env/arg pages and those are %99 certainly going to
+@@ -105,6 +117,11 @@ void __flush_anon_page(struct page *page
+ {
+       unsigned long addr = (unsigned long) page_address(page);
+ 
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++              return;
++      }
++
+       if (pages_do_alias(addr, vmaddr)) {
+               if (page_mapped(page) && !Page_dcache_dirty(page)) {
+                       void *kaddr;
+@@ -123,8 +140,10 @@ void __flush_icache_page(struct vm_area_
+ {
+       unsigned long addr;
+ 
+-      if (PageHighMem(page))
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
+               return;
++      }
+ 
+       addr = (unsigned long) page_address(page);
+       flush_data_cache_page(addr);
+@@ -142,7 +161,12 @@ void __update_cache(struct vm_area_struc
+       if (unlikely(!pfn_valid(pfn)))
+               return;
+       page = pfn_to_page(pfn);
+-      if (page_mapping(page) && Page_dcache_dirty(page)) {
++      if (!Page_dcache_dirty(page))
++              return;
++
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++      } else if (page_mapping(page)) {
+               addr = (unsigned long) page_address(page);
+               if (exec || pages_do_alias(addr, address & PAGE_MASK))
+                       flush_data_cache_page(addr);

diff --git a/target/linux/generic/patches-4.4/101-MIPS-fix-cache-flushing-for-highmem-pages.patch b/target/linux/generic/patches-4.4/101-MIPS-fix-cache-flushing-for-highmem-pages.patch
new file mode 100644 (file)
index 0000000..d7220af
--- /dev/null
+++ b/target/linux/generic/patches-4.4/101-MIPS-fix-cache-flushing-for-highmem-pages.patch
@@ -0,0 +1,95 @@
+From: Felix Fietkau <nbd@openwrt.org>
+Date: Sun, 24 Jan 2016 01:03:51 +0100
+Subject: [PATCH] MIPS: fix cache flushing for highmem pages
+
+Most cache flush ops were no-op for highmem pages. This led to nasty
+segfaults and (in the case of page_address(page) == NULL) kernel
+crashes.
+
+Fix this by always flushing highmem pages using kmap/kunmap_atomic
+around the actual cache flush. This might be a bit inefficient, but at
+least it's stable.
+
+Signed-off-by: Felix Fietkau <nbd@openwrt.org>
+---
+
+--- a/arch/mips/mm/cache.c
++++ b/arch/mips/mm/cache.c
+@@ -14,6 +14,7 @@
+ #include <linux/sched.h>
+ #include <linux/syscalls.h>
+ #include <linux/mm.h>
++#include <linux/highmem.h>
+ 
+ #include <asm/cacheflush.h>
+ #include <asm/processor.h>
+@@ -78,18 +79,29 @@ SYSCALL_DEFINE3(cacheflush, unsigned lon
+       return 0;
+ }
+ 
++static void
++flush_highmem_page(struct page *page)
++{
++      void *addr = kmap_atomic(page);
++      flush_data_cache_page((unsigned long)addr);
++      kunmap_atomic(addr);
++}
++
+ void __flush_dcache_page(struct page *page)
+ {
+       struct address_space *mapping = page_mapping(page);
+       unsigned long addr;
+ 
+-      if (PageHighMem(page))
+-              return;
+       if (mapping && !mapping_mapped(mapping)) {
+               SetPageDcacheDirty(page);
+               return;
+       }
+ 
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++              return;
++      }
++
+       /*
+        * We could delay the flush for the !page_mapping case too.  But that
+        * case is for exec env/arg pages and those are %99 certainly going to
+@@ -105,6 +117,11 @@ void __flush_anon_page(struct page *page
+ {
+       unsigned long addr = (unsigned long) page_address(page);
+ 
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++              return;
++      }
++
+       if (pages_do_alias(addr, vmaddr)) {
+               if (page_mapped(page) && !Page_dcache_dirty(page)) {
+                       void *kaddr;
+@@ -123,8 +140,10 @@ void __flush_icache_page(struct vm_area_
+ {
+       unsigned long addr;
+ 
+-      if (PageHighMem(page))
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
+               return;
++      }
+ 
+       addr = (unsigned long) page_address(page);
+       flush_data_cache_page(addr);
+@@ -142,7 +161,12 @@ void __update_cache(struct vm_area_struc
+       if (unlikely(!pfn_valid(pfn)))
+               return;
+       page = pfn_to_page(pfn);
+-      if (page_mapping(page) && Page_dcache_dirty(page)) {
++      if (!Page_dcache_dirty(page))
++              return;
++
++      if (PageHighMem(page)) {
++              flush_highmem_page(page);
++      } else if (page_mapping(page)) {
+               addr = (unsigned long) page_address(page);
+               if (exec || pages_do_alias(addr, address & PAGE_MASK))
+                       flush_data_cache_page(addr);