Now the random crashes are observed on ARM TI am437x-idk-evm used with
-RT Kernel v4.4-rt2 and with Highmem enabled.
The reason of issue is that, newly introduced switch_kmaps() does not
take into account FIX_KMAP_BEGIN, which was re-added by
commit a5f4c561b3b1 ("ARM: 8415/1: early fixmap support for earlycon")
(K4.3) for ARM and since that the value of FIX_KMAP_BEGIN
is not 0 any more.
Hence update switch_kmaps() so it will take into FIX_KMAP_BEGIN while
calculating fixmap idx. This patch also introduces fixmap_idx() to
make code simpler and remove duplicated code.
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
arch/arm/mm/highmem.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index deabc36..542692d 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -34,6 +34,11 @@ static inline pte_t get_fixmap_pte(unsigned long vaddr)
return *ptep;
}
+static unsigned int fixmap_idx(int type)
+{
+ return FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+}
+
void *kmap(struct page *page)
{
might_sleep();
@@ -80,7 +85,7 @@ void *kmap_atomic(struct page *page)
type = kmap_atomic_idx_push();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
/*
@@ -110,7 +115,7 @@ void __kunmap_atomic(void *kvaddr)
if (kvaddr >= (void *)FIXADDR_START) {
type = kmap_atomic_idx();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
if (cache_is_vivt())
__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
@@ -146,7 +151,7 @@ void *kmap_atomic_pfn(unsigned long pfn)
return page_address(page);
type = kmap_atomic_idx_push();
- idx = FIX_KMAP_BEGIN + type + KM_TYPE_NR * smp_processor_id();
+ idx = fixmap_idx(type);
vaddr = __fix_to_virt(idx);
#ifdef CONFIG_DEBUG_HIGHMEM
BUG_ON(!pte_none(get_fixmap_pte(vaddr)));
@@ -167,7 +172,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
* Clear @prev's kmap_atomic mappings
*/
for (i = 0; i < prev_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
+ int idx = fixmap_idx(i);
set_fixmap_pte(idx, __pte(0));
}
@@ -175,7 +180,7 @@ void switch_kmaps(struct task_struct *prev_p, struct task_struct *next_p)
* Restore @next_p's kmap_atomic mappings
*/
for (i = 0; i < next_p->kmap_idx; i++) {
- int idx = i + KM_TYPE_NR * smp_processor_id();
+ int idx = fixmap_idx(i);
if (!pte_none(next_p->kmap_pte[i]))
set_fixmap_pte(idx, next_p->kmap_pte[i]);
--
2.7.0
--
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