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Message-ID: <20160114213048.GB19062@n2100.arm.linux.org.uk>
Date: Thu, 14 Jan 2016 21:30:48 +0000
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Grygorii Strashko <grygorii.strashko@...com>
Cc: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Sekhar Nori <nsekhar@...com>, linux-rt-users@...r.kernel.org,
linux-arm <linux-arm-kernel@...ts.infradead.org>,
linux-kernel@...r.kernel.org
Subject: Re: [4.4-rc6-rt1 PATCH 0/2] ARM: am437x: boot test report
On Thu, Jan 14, 2016 at 10:11:09PM +0200, Grygorii Strashko wrote:
> diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
> index deabc36..b9b4f9c 100644
> --- a/arch/arm/mm/highmem.c
> +++ b/arch/arm/mm/highmem.c
> @@ -167,7 +167,7 @@ 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 = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id();
>
> set_fixmap_pte(idx, __pte(0));
> }
> @@ -175,7 +175,7 @@ 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 = FIX_KMAP_BEGIN + i + KM_TYPE_NR * smp_processor_id();
>
> if (!pte_none(next_p->kmap_pte[i]))
> set_fixmap_pte(idx, next_p->kmap_pte[i]);
This looks like it introduces the 4th and 5th copies of the same
calcuation, so can I suggest that we do this to prevent this kind
of error?
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index d02f8187b1cc..61f0d5941116 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();
@@ -79,7 +84,7 @@ 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
/*
@@ -106,7 +111,7 @@ 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);
@@ -138,7 +143,7 @@ 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)));
--
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