openwrt/target/linux/generic/pending-4.14/100-MIPS-fix-cache-flushing-for-highmem-pages.patch
Hauke Mehrtens b3f95490b9 kernel: generic: Add kernel 4.14 support
This adds initial support for kernel 4.14 based on the patches for
kernel 4.9.

In the configuration I deactivated some of the new possible security
features like:
CONFIG_REFCOUNT_FULL
CONFIG_SLAB_FREELIST_HARDENED
CONFIG_SOFTLOCKUP_DETECTOR
CONFIG_WARN_ALL_UNSEEDED_RANDOM

And these overlay FS options are also deactivated:
CONFIG_OVERLAY_FS_INDEX
CONFIG_OVERLAY_FS_REDIRECT_DIR

I activated this:
CONFIG_FORTIFY_SOURCE
CONFIG_POSIX_TIMERS
CONFIG_SLAB_MERGE_DEFAULT
CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED

I am not sure if I did the porting correct for the following patches:
target/linux/generic/backport-4.14/020-backport_netfilter_rtcache.patch
target/linux/generic/hack-4.14/220-gc_sections.patch
target/linux/generic/hack-4.14/321-powerpc_crtsavres_prereq.patch
target/linux/generic/pending-4.14/305-mips_module_reloc.patch
target/linux/generic/pending-4.14/611-netfilter_match_bypass_default_table.patch
target/linux/generic/pending-4.14/680-NET-skip-GRO-for-foreign-MAC-addresses.patch

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
2017-12-16 22:11:19 +01:00

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Diff

From: Felix Fietkau <nbd@nbd.name>
Subject: 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@nbd.name>
---
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -116,6 +116,13 @@ void __flush_anon_page(struct page *page
{
unsigned long addr = (unsigned long) page_address(page);
+ if (PageHighMem(page)) {
+ addr = (unsigned long)kmap_atomic(page);
+ flush_data_cache_page(addr);
+ __kunmap_atomic((void *)addr);
+ return;
+ }
+
if (pages_do_alias(addr, vmaddr)) {
if (page_mapcount(page) && !Page_dcache_dirty(page)) {
void *kaddr;