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[PATCH 4.8 32/49] sparc64: Handle extremely large kernel TSB range flushes sanely.

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4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "David S. Miller" <davem@davemloft.net>


[ Upstream commit 849c498766060a16aad5b0e0d03206726e7d2fa4 ]

If the number of pages we are flushing is more than twice the number
of entries in the TSB, just scan the TSB table for matches rather
than probing each and every page in the range.

Based upon a patch and report by James Clarke.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/sparc/mm/tsb.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -27,6 +27,20 @@ static inline int tag_compare(unsigned l
 	return (tag == (vaddr >> 22));
 }
 
+static void flush_tsb_kernel_range_scan(unsigned long start, unsigned long end)
+{
+	unsigned long idx;
+
+	for (idx = 0; idx < KERNEL_TSB_NENTRIES; idx++) {
+		struct tsb *ent = &swapper_tsb[idx];
+		unsigned long match = idx << 13;
+
+		match |= (ent->tag << 22);
+		if (match >= start && match < end)
+			ent->tag = (1UL << TSB_TAG_INVALID_BIT);
+	}
+}
+
 /* TSB flushes need only occur on the processor initiating the address
  * space modification, not on each cpu the address space has run on.
  * Only the TLB flush needs that treatment.
@@ -36,6 +50,9 @@ void flush_tsb_kernel_range(unsigned lon
 {
 	unsigned long v;
 
+	if ((end - start) >> PAGE_SHIFT >= 2 * KERNEL_TSB_NENTRIES)
+		return flush_tsb_kernel_range_scan(start, end);
+
 	for (v = start; v < end; v += PAGE_SIZE) {
 		unsigned long hash = tsb_hash(v, PAGE_SHIFT,
 					      KERNEL_TSB_NENTRIES);

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[PATCH 4.8 00/49] 4.8.10-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 07/49] ipv4: allow local fragmentation in ip_finish_output_gso() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 42/49] sparc64: Convert NG4copy_{from,to}_user to accurate exception reporting. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 36/49] sparc64: Handle extremely large kernel TLB range flushes more gracefully. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 43/49] sparc64: Convert NGcopy_{from,to}_user to accurate exception reporting. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 24/49] mlxsw: spectrum: Fix refcount bug on span entries Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 33/49] sparc64: Fix illegal relative branches in hypervisor patched TLB code. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:30 +0100
  [PATCH 4.8 37/49] sparc64: Delete __ret_efault. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 04/49] bgmac: stop clearing DMA receive control register right after it is set Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 11/49] dccp: fix out of bound access in dccp_v4_err() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 32/49] sparc64: Handle extremely large kernel TSB range flushes sanely. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 02/49] net: clear sk_err_soft in sk_clone_lock() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 28/49] sctp: change sk state only when it has assocs in sctp_shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 10/49] dccp: do not send reset to already closed sockets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 38/49] sparc64: Prepare to move to more saner user copy exception handling. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 09/49] dccp: do not release listeners too soon Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 40/49] sparc64: Convert GENcopy_{from,to}_user to accurate exception reporting. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 15/49] bpf: fix htab map destruction when extra reserve is in use Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  [PATCH 4.8 13/49] ipv6: dccp: add missing bind_conflict to dccp_ipv6_mapped Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 10:40 +0100
  Re: [PATCH 4.8 00/49] 4.8.10-stable review Guenter Roeck <linux@roeck-us.net> - 2016-11-19 17:30 +0100
    Re: [PATCH 4.8 00/49] 4.8.10-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-11-19 18:00 +0100
  Re: [PATCH 4.8 00/49] 4.8.10-stable review Shuah Khan <shuah.kh@samsung.com> - 2016-11-21 17:40 +0100

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