Patch "MIPS: Flush wrong invalid FTLB entry for huge page" has been added to the 4.10-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    MIPS: Flush wrong invalid FTLB entry for huge page

to the 4.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mips-flush-wrong-invalid-ftlb-entry-for-huge-page.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0115f6cbf26663c86496bc56eeea293f85b77897 Mon Sep 17 00:00:00 2001
From: Huacai Chen <chenhc@lemote.com>
Date: Thu, 16 Mar 2017 21:00:27 +0800
Subject: MIPS: Flush wrong invalid FTLB entry for huge page

From: Huacai Chen <chenhc@lemote.com>

commit 0115f6cbf26663c86496bc56eeea293f85b77897 upstream.

On VTLB+FTLB platforms (such as Loongson-3A R2), FTLB's pagesize is
usually configured the same as PAGE_SIZE. In such a case, Huge page
entry is not suitable to write in FTLB.

Unfortunately, when a huge page is created, its page table entries
haven't created immediately. Then the TLB refill handler will fetch an
invalid page table entry which has no "HUGE" bit, and this entry may be
written to FTLB. Since it is invalid, TLB load/store handler will then
use tlbwi to write the valid entry at the same place. However, the
valid entry is a huge page entry which isn't suitable for FTLB.

Our solution is to modify build_huge_handler_tail. Flush the invalid
old entry (whether it is in FTLB or VTLB, this is in order to reduce
branches) and use tlbwr to write the valid new entry.

Signed-off-by: Rui Wang <wangr@lemote.com>
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J . Hill <Steven.Hill@caviumnetworks.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: Huacai Chen <chenhc@lemote.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15754/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/mm/tlbex.c |   25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -762,7 +762,8 @@ static void build_huge_update_entries(u3
 static void build_huge_handler_tail(u32 **p, struct uasm_reloc **r,
 				    struct uasm_label **l,
 				    unsigned int pte,
-				    unsigned int ptr)
+				    unsigned int ptr,
+				    unsigned int flush)
 {
 #ifdef CONFIG_SMP
 	UASM_i_SC(p, pte, 0, ptr);
@@ -771,6 +772,22 @@ static void build_huge_handler_tail(u32
 #else
 	UASM_i_SW(p, pte, 0, ptr);
 #endif
+	if (cpu_has_ftlb && flush) {
+		BUG_ON(!cpu_has_tlbinv);
+
+		UASM_i_MFC0(p, ptr, C0_ENTRYHI);
+		uasm_i_ori(p, ptr, ptr, MIPS_ENTRYHI_EHINV);
+		UASM_i_MTC0(p, ptr, C0_ENTRYHI);
+		build_tlb_write_entry(p, l, r, tlb_indexed);
+
+		uasm_i_xori(p, ptr, ptr, MIPS_ENTRYHI_EHINV);
+		UASM_i_MTC0(p, ptr, C0_ENTRYHI);
+		build_huge_update_entries(p, pte, ptr);
+		build_huge_tlb_write_entry(p, l, r, pte, tlb_random, 0);
+
+		return;
+	}
+
 	build_huge_update_entries(p, pte, ptr);
 	build_huge_tlb_write_entry(p, l, r, pte, tlb_indexed, 0);
 }
@@ -2197,7 +2214,7 @@ static void build_r4000_tlb_load_handler
 		uasm_l_tlbl_goaround2(&l, p);
 	}
 	uasm_i_ori(&p, wr.r1, wr.r1, (_PAGE_ACCESSED | _PAGE_VALID));
-	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2);
+	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2, 1);
 #endif
 
 	uasm_l_nopage_tlbl(&l, p);
@@ -2252,7 +2269,7 @@ static void build_r4000_tlb_store_handle
 	build_tlb_probe_entry(&p);
 	uasm_i_ori(&p, wr.r1, wr.r1,
 		   _PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID | _PAGE_DIRTY);
-	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2);
+	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2, 1);
 #endif
 
 	uasm_l_nopage_tlbs(&l, p);
@@ -2308,7 +2325,7 @@ static void build_r4000_tlb_modify_handl
 	build_tlb_probe_entry(&p);
 	uasm_i_ori(&p, wr.r1, wr.r1,
 		   _PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID | _PAGE_DIRTY);
-	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2);
+	build_huge_handler_tail(&p, &r, &l, wr.r1, wr.r2, 0);
 #endif
 
 	uasm_l_nopage_tlbm(&l, p);


Patches currently in stable-queue which might be from chenhc@lemote.com are

queue-4.10/mips-flush-wrong-invalid-ftlb-entry-for-huge-page.patch
queue-4.10/mips-check-tlb-before-handle_ri_rdhwr-for-loongson-3.patch
queue-4.10/mips-c-r4k-fix-loongson-3-s-vcache-scache-waysize-calculation.patch
queue-4.10/mips-add-mips_cpu_ftlb-for-loongson-3a-r2.patch