On 07/30/2014 05:48 PM, Huacai Chen wrote:
Hi, David,
For non-Octeon CPU, htlb_info.huge_pte is equal to K0, but I don't
know much about Octeon. So I think you know whether we should use K0
or htlb_info.huge_pte here, since you are the original author.
This is why I requested that somebody show me a disassembly of the
faulty handler. I cannot tell where the problem is unless I see that.
Really I think the problem is in build_is_huge_pte(), where we are
clobbering 'tmp' which is K0.
So you could reload tmp/K0 in build_is_huge_pte().
On Thu, Jul 31, 2014 at 5:44 AM, David Daney
<ddaney@xxxxxxxxxxxxxxxxxx> wrote:
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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