path: root/arch/sparc/mm
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authorDavid S. Miller <>2014-08-04 20:07:37 -0700
committerDavid S. Miller <>2014-08-04 20:16:00 -0700
commit4ca9a23765da3260058db3431faf5b4efd8cf926 (patch)
treea7bafd8e1e1ed1de0e1afa82f4a45fbd485ff41e /arch/sparc/mm
parentfe418231b195c205701c0cc550a03f6c9758fd9e (diff)
sparc64: Guard against flushing openfirmware mappings.
Based almost entirely upon a patch by Christopher Alexander Tobias Schulze. In commit db64fe02258f1507e13fe5212a989922323685ce ("mm: rewrite vmap layer") lazy VMAP tlb flushing was added to the vmalloc layer. This causes problems on sparc64. Sparc64 has two VMAP mapped regions and they are not contiguous with eachother. First we have the malloc mapping area, then another unrelated region, then the vmalloc region. This "another unrelated region" is where the firmware is mapped. If the lazy TLB flushing logic in the vmalloc code triggers after we've had both a module unload and a vfree or similar, it will pass an address range that goes from somewhere inside the malloc region to somewhere inside the vmalloc region, and thus covering the openfirmware area entirely. The sparc64 kernel learns about openfirmware's dynamic mappings in this region early in the boot, and then services TLB misses in this area. But openfirmware has some locked TLB entries which are not mentioned in those dynamic mappings and we should thus not disturb them. These huge lazy TLB flush ranges causes those openfirmware locked TLB entries to be removed, resulting in all kinds of problems including hard hangs and crashes during reboot/reset. Besides causing problems like this, such huge TLB flush ranges are also incredibly inefficient. A plea has been made with the author of the VMAP lazy TLB flushing code, but for now we'll put a safety guard into our flush_tlb_kernel_range() implementation. Since the implementation has become non-trivial, stop defining it as a macro and instead make it a function in a C source file. Signed-off-by: David S. Miller <>
Diffstat (limited to 'arch/sparc/mm')
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index db5ddde0b335..2cfb0f25e0ed 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -2707,3 +2707,26 @@ void hugetlb_setup(struct pt_regs *regs)
+#ifdef CONFIG_SMP
+#define do_flush_tlb_kernel_range smp_flush_tlb_kernel_range
+#define do_flush_tlb_kernel_range __flush_tlb_kernel_range
+void flush_tlb_kernel_range(unsigned long start, unsigned long end)
+ if (start < HI_OBP_ADDRESS && end > LOW_OBP_ADDRESS) {
+ if (start < LOW_OBP_ADDRESS) {
+ flush_tsb_kernel_range(start, LOW_OBP_ADDRESS);
+ do_flush_tlb_kernel_range(start, LOW_OBP_ADDRESS);
+ }
+ if (end > HI_OBP_ADDRESS) {
+ flush_tsb_kernel_range(end, HI_OBP_ADDRESS);
+ do_flush_tlb_kernel_range(end, HI_OBP_ADDRESS);
+ }
+ } else {
+ flush_tsb_kernel_range(start, end);
+ do_flush_tlb_kernel_range(start, end);
+ }