The change to flush_kernel_vmap_range() wasn't sufficient to avoid the
SMP stalls. The
problem is some drivers call these routines with interrupts disabled.
Interrupts need to be
enabled for flush_tlb_all() and flush_cache_all() to work. This version
adds checks to ensure
interrupts are not disabled before calling routines that need IPI
interrupts. When interrupts
are disabled, we now drop into slower code.
The attached change fixes the ordering of cache and TLB flushes in
several cases. When we
flush the cache using the existing PTE/TLB entries, we need to flush the
TLB after doing the cache
flush. We don't need to do this when we flush the entire instruction
and data caches as these
flushes don't use the existing TLB entries. The same is true for
tmpalias region flushes.
The flush_kernel_vmap_range() and invalidate_kernel_vmap_range()
routines have been
updated.
Secondly, we added a new purge_kernel_dcache_range_asm() routine to
pacache.S and
use it in invalidate_kernel_vmap_range(). Nominally, purges are faster
than flushes as the
cache lines don't have to be written back to memory.
Hopefully, this is sufficient to resolve the remaining problems due to
cache speculation. So far,
testing indicates that this is the case. I did work up a patch using
tmpalias flushes, but there
is a performance hit because we need the physical address for each page,
and we also need
to sequence access to the tmpalias flush code. This increases the
probability of stalls.
Signed-off-by: John David Anglin <dave.anglin@xxxxxxxx>
diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index 3742508cc534..bd5ce31936f5 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -26,6 +26,7 @@ void flush_user_icache_range_asm(unsigned long, unsigned long);
void flush_kernel_icache_range_asm(unsigned long, unsigned long);
void flush_user_dcache_range_asm(unsigned long, unsigned long);
void flush_kernel_dcache_range_asm(unsigned long, unsigned long);
+void purge_kernel_dcache_range_asm(unsigned long, unsigned long);
void flush_kernel_dcache_page_asm(void *);
void flush_kernel_icache_page(void *);
diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index 19c0c141bc3f..c9c122da222f 100644
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -465,10 +465,14 @@ EXPORT_SYMBOL(copy_user_page);
int __flush_tlb_range(unsigned long sid, unsigned long start,
unsigned long end)
{
- unsigned long flags, size;
+ unsigned long flags;
- size = (end - start);
- if (size >= parisc_tlb_flush_threshold) {
+#ifdef CONFIG_SMP
+ if (!arch_irqs_disabled() &&
+ end - start >= parisc_tlb_flush_threshold) {
+#else
+ 1f (end - start >= parisc_tlb_flush_threshold) {
+#endif
flush_tlb_all();
return 1;
}
@@ -539,13 +543,15 @@ void flush_cache_mm(struct mm_struct *mm)
struct vm_area_struct *vma;
pgd_t *pgd;
- /* Flush the TLB to avoid speculation if coherency is required. */
- if (parisc_requires_coherency())
- flush_tlb_all();
-
/* Flushing the whole cache on each cpu takes forever on
rp3440, etc. So, avoid it if the mm isn't too big. */
+#ifdef CONFIG_SMP
+ if (!arch_irqs_disabled() &&
+ mm_total_size(mm) >= parisc_cache_flush_threshold) {
+#else
if (mm_total_size(mm) >= parisc_cache_flush_threshold) {
+#endif
+ flush_tlb_all();
flush_cache_all();
return;
}
@@ -553,9 +559,9 @@ void flush_cache_mm(struct mm_struct *mm)
if (mm->context == mfsp(3)) {
for (vma = mm->mmap; vma; vma = vma->vm_next) {
flush_user_dcache_range_asm(vma->vm_start, vma->vm_end);
- if ((vma->vm_flags & VM_EXEC) == 0)
- continue;
- flush_user_icache_range_asm(vma->vm_start, vma->vm_end);
+ if (vma->vm_flags & VM_EXEC)
+ flush_user_icache_range_asm(vma->vm_start, vma->vm_end);
+ flush_tlb_range(vma, vma->vm_start, vma->vm_end);
}
return;
}
@@ -581,14 +587,13 @@ void flush_cache_mm(struct mm_struct *mm)
void flush_cache_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
- BUG_ON(!vma->vm_mm->context);
-
- /* Flush the TLB to avoid speculation if coherency is required. */
- if (parisc_requires_coherency())
+#ifdef CONFIG_SMP
+ if (!arch_irqs_disabled() &&
+ end - start >= parisc_cache_flush_threshold) {
+#else
+ if (end - start >= parisc_cache_flush_threshold) {
+#endif
flush_tlb_range(vma, start, end);
-
- if ((end - start) >= parisc_cache_flush_threshold
- || vma->vm_mm->context != mfsp(3)) {
flush_cache_all();
return;
}
@@ -596,6 +601,7 @@ void flush_cache_range(struct vm_area_struct *vma,
flush_user_dcache_range_asm(start, end);
if (vma->vm_flags & VM_EXEC)
flush_user_icache_range_asm(start, end);
+ flush_tlb_range(vma, start, end);
}
void
@@ -604,8 +610,7 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long
BUG_ON(!vma->vm_mm->context);
if (pfn_valid(pfn)) {
- if (parisc_requires_coherency())
- flush_tlb_page(vma, vmaddr);
+ flush_tlb_page(vma, vmaddr);
__flush_cache_page(vma, vmaddr, PFN_PHYS(pfn));
}
}
@@ -613,21 +618,41 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long
void flush_kernel_vmap_range(void *vaddr, int size)
{
unsigned long start = (unsigned long)vaddr;
+ unsigned long end = start + size;
- if ((unsigned long)size > parisc_cache_flush_threshold)
+#ifdef CONFIG_SMP
+ if (!arch_irqs_disabled() &&
+ (unsigned long)size >= parisc_cache_flush_threshold) {
+#else
+ if ((unsigned long)size >= parisc_cache_flush_threshold) {
+#endif
+ flush_tlb_kernel_range(start, end);
flush_data_cache();
- else
- flush_kernel_dcache_range_asm(start, start + size);
+ return;
+ }
+
+ flush_kernel_dcache_range_asm(start, end);
+ flush_tlb_kernel_range(start, end);
}
EXPORT_SYMBOL(flush_kernel_vmap_range);
void invalidate_kernel_vmap_range(void *vaddr, int size)
{
unsigned long start = (unsigned long)vaddr;
+ unsigned long end = start + size;
- if ((unsigned long)size > parisc_cache_flush_threshold)
+#ifdef CONFIG_SMP
+ if (!arch_irqs_disabled() &&
+ (unsigned long)size >= parisc_cache_flush_threshold) {
+#else
+ if ((unsigned long)size >= parisc_cache_flush_threshold) {
+#endif
+ flush_tlb_kernel_range(start, end);
flush_data_cache();
- else
- flush_kernel_dcache_range_asm(start, start + size);
+ return;
+ }
+
+ purge_kernel_dcache_range_asm(start, end);
+ flush_tlb_kernel_range(start, end);
}
EXPORT_SYMBOL(invalidate_kernel_vmap_range);
diff --git a/arch/parisc/kernel/pacache.S b/arch/parisc/kernel/pacache.S
index 2d40c4ff3f69..67b0f7532e83 100644
--- a/arch/parisc/kernel/pacache.S
+++ b/arch/parisc/kernel/pacache.S
@@ -1110,6 +1110,28 @@ ENTRY_CFI(flush_kernel_dcache_range_asm)
.procend
ENDPROC_CFI(flush_kernel_dcache_range_asm)
+ENTRY_CFI(purge_kernel_dcache_range_asm)
+ .proc
+ .callinfo NO_CALLS
+ .entry
+
+ ldil L%dcache_stride, %r1
+ ldw R%dcache_stride(%r1), %r23
+ ldo -1(%r23), %r21
+ ANDCM %r26, %r21, %r26
+
+1: cmpb,COND(<<),n %r26, %r25,1b
+ pdc,m %r23(%r26)
+
+ sync
+ syncdma
+ bv %r0(%r2)
+ nop
+ .exit
+
+ .procend
+ENDPROC_CFI(purge_kernel_dcache_range_asm)
+
ENTRY_CFI(flush_user_icache_range_asm)
.proc
.callinfo NO_CALLS
