On 07/30/2014 02:41 PM, James Hogan wrote:
Hi Huacai,
On Tuesday 29 July 2014 14:54:40 Huacai Chen wrote:
In commit 2c8c53e28f1 (MIPS: Optimize TLB handlers for Octeon CPUs)
build_r4000_tlb_refill_handler() is modified. But it doesn't compatible
with the original code in HUGETLB case. Because there is a copy & paste
error and one line of code is missing. It is very easy to produce a bug
with LTP's hugemmap05 test.
Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
Signed-off-by: Binbin Zhou <zhoubb@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
arch/mips/mm/tlbex.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index e80e10b..343fe0f 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -1299,6 +1299,7 @@ static void build_r4000_tlb_refill_handler(void)
}
#ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
uasm_l_tlb_huge_update(&l, p);
+ UASM_i_LW(&p, K0, 0, K1);
build_huge_update_entries(&p, htlb_info.huge_pte, K1);
build_huge_tlb_write_entry(&p, &l, &r, K0, tlb_random,
htlb_info.restore_scratch);
build_huge_tlb_write_entry only uses K0 as a temp and clobbers without using
the value, so the K0 must be being used by the code generated by
build_huge_update_entires, but the patch you mentioned changed the second
argument from K0 to htlb_info.huge_pte.
So should the K0 in the new UASM_i_LW call be changed to htlb_info.huge_pte
too?
I don't know. You have to dump out the generated handler (by #define
DEBUG at the top of the file), then assemble/disassemble it. Looking at
the disassembly, we could make sensible statements about what is happening.
(David Daney on Cc)
Thanks
James
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