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Re: [Qemu-devel] [PATCH 2/7] target-mips: support Page Frame Number Exte
From: |
James Hogan |
Subject: |
Re: [Qemu-devel] [PATCH 2/7] target-mips: support Page Frame Number Extension field |
Date: |
Tue, 28 Apr 2015 14:47:25 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
On 28/04/15 14:35, James Hogan wrote:
>
>
> On 28/04/15 13:41, Leon Alrae wrote:
>> Update tlb->PFN to contain PFN concatenated with PFNX. PFNX is 0 if large
>> physical address is not supported.
>>
>> Signed-off-by: Leon Alrae <address@hidden>
>> ---
>> target-mips/op_helper.c | 32 ++++++++++++++++++++++++++------
>> 1 file changed, 26 insertions(+), 6 deletions(-)
>>
>> diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
>> index c9a60bd..6bff927 100644
>> --- a/target-mips/op_helper.c
>> +++ b/target-mips/op_helper.c
>> @@ -1825,6 +1825,16 @@ static void r4k_mips_tlb_flush_extra (CPUMIPSState
>> *env, int first)
>> }
>> }
>>
>> +static inline uint64_t get_tlb_pfn_from_entrylo(uint64_t entrylo)
>> +{
>> +#if defined(TARGET_MIPS64)
>> + return extract64(entrylo, 6, 54);
>> +#else
>> + return extract64(entrylo, 6, 24) | /* PFN */
>> + (extract64(entrylo, 32, 32) << 24); /* PFNX */
>
> Where does the 32,32 come from? The PRA I have seems to imply that PFNX
> starts at bit 30 and goes up to bit 54.
Ah right, I guess this is from the output of MFHC0/MTHC0 instructions.
The specification of those instructions specify the mangling they do:
GPR[rt]_31:0 <- data_61..30
GPR[rt]_63..32 <- (data_61)^31 // sign-extend
Note how the field it extracts starts at bit 30. IMO the stored values
of EntryLo PFN should be continuous rather than split up like the
MFHC0/MTHC0 versions.
Cheers
James
>
> That would of course also mean that the code for mfc0 EntryLo* needs
> tweaking so that PFNX doesn't cause XI/RI bits to be set at bits 30,31
> (haven't looked at other patches yet).
>
>> +#endif
>> +}
>> +
>> static void r4k_fill_tlb(CPUMIPSState *env, int idx)
>> {
>> r4k_tlb_t *tlb;
>> @@ -1848,13 +1858,13 @@ static void r4k_fill_tlb(CPUMIPSState *env, int idx)
>> tlb->C0 = (env->CP0_EntryLo0 >> 3) & 0x7;
>> tlb->XI0 = (env->CP0_EntryLo0 >> CP0EnLo_XI) & 1;
>> tlb->RI0 = (env->CP0_EntryLo0 >> CP0EnLo_RI) & 1;
>> - tlb->PFN[0] = (env->CP0_EntryLo0 >> 6) << 12;
>> + tlb->PFN[0] = get_tlb_pfn_from_entrylo(env->CP0_EntryLo0) << 12;
>> tlb->V1 = (env->CP0_EntryLo1 & 2) != 0;
>> tlb->D1 = (env->CP0_EntryLo1 & 4) != 0;
>> tlb->C1 = (env->CP0_EntryLo1 >> 3) & 0x7;
>> tlb->XI1 = (env->CP0_EntryLo1 >> CP0EnLo_XI) & 1;
>> tlb->RI1 = (env->CP0_EntryLo1 >> CP0EnLo_RI) & 1;
>> - tlb->PFN[1] = (env->CP0_EntryLo1 >> 6) << 12;
>> + tlb->PFN[1] = get_tlb_pfn_from_entrylo(env->CP0_EntryLo1) << 12;
>> }
>>
>> void r4k_helper_tlbinv(CPUMIPSState *env)
>> @@ -1971,6 +1981,16 @@ void r4k_helper_tlbp(CPUMIPSState *env)
>> }
>> }
>>
>> +static inline uint64_t get_entrylo_pfn_from_tlb(uint64_t tlb_pfn)
>> +{
>> +#if defined(TARGET_MIPS64)
>> + return tlb_pfn << 6;
>> +#else
>> + return (extract64(tlb_pfn, 0, 24) << 6) | /* PFN */
>> + (extract64(tlb_pfn, 24, 32) << 32); /* PFNX */
>
> same again. shouldn't it be 25 bits starting at bit 24, shifted to start
> at bit 30?
>
> Cheers
> James
>
>> +#endif
>> +}
>> +
>> void r4k_helper_tlbr(CPUMIPSState *env)
>> {
>> r4k_tlb_t *tlb;
>> @@ -1997,12 +2017,12 @@ void r4k_helper_tlbr(CPUMIPSState *env)
>> env->CP0_PageMask = tlb->PageMask;
>> env->CP0_EntryLo0 = tlb->G | (tlb->V0 << 1) | (tlb->D0 << 2) |
>> ((uint64_t)tlb->RI0 << CP0EnLo_RI) |
>> - ((uint64_t)tlb->XI0 << CP0EnLo_XI) |
>> - (tlb->C0 << 3) | (tlb->PFN[0] >> 6);
>> + ((uint64_t)tlb->XI0 << CP0EnLo_XI) | (tlb->C0 << 3)
>> |
>> + get_entrylo_pfn_from_tlb(tlb->PFN[0] >> 12);
>> env->CP0_EntryLo1 = tlb->G | (tlb->V1 << 1) | (tlb->D1 << 2) |
>> ((uint64_t)tlb->RI1 << CP0EnLo_RI) |
>> - ((uint64_t)tlb->XI1 << CP0EnLo_XI) |
>> - (tlb->C1 << 3) | (tlb->PFN[1] >> 6);
>> + ((uint64_t)tlb->XI1 << CP0EnLo_XI) | (tlb->C1 << 3)
>> |
>> + get_entrylo_pfn_from_tlb(tlb->PFN[1] >> 12);
>> }
>> }
>>
>>
>
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[Qemu-devel] [PATCH 7/7] target-mips: enable XPA and LPA features, Leon Alrae, 2015/04/28
[Qemu-devel] [PATCH 6/7] target-mips: remove invalid comments in translate_init.c, Leon Alrae, 2015/04/28
[Qemu-devel] [PATCH 4/7] target-mips: add MTHC0 and MFHC0 instructions, Leon Alrae, 2015/04/28