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Re: [Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu ex
From: |
James Hogan |
Subject: |
Re: [Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu exception |
Date: |
Thu, 29 Oct 2015 23:42:56 +0000 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Thu, Oct 29, 2015 at 05:17:52PM +0000, Yongbok Kim wrote:
> Correct updating XContext.Region field on mmu exceptions.
> If Config3.CTXTC = 0 then the R field of XContext has to be updated
> with the value of bits 63..62 of the virtual address upon a TLB
> exception.
It wouldn't hurt to mention how the existing behaviour is wrong, since
it requires a little staring (and counting of zeros) to see it, i.e.
that the old mask incorrectly selected bits 47:46 of the address, and
shifted them down into the middle of BadVPN2.
> Also fixed the below line which overs 80 characters.
>
> Signed-off-by: Yongbok Kim <address@hidden>
Reviewed-by: James Hogan <address@hidden>
Cheers
James
> ---
> target-mips/helper.c | 7 ++++---
> 1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/target-mips/helper.c b/target-mips/helper.c
> index 2d86323..b3fe816 100644
> --- a/target-mips/helper.c
> +++ b/target-mips/helper.c
> @@ -293,9 +293,10 @@ static void raise_mmu_exception(CPUMIPSState *env,
> target_ulong address,
> (env->CP0_EntryHi & 0xFF) | (address & (TARGET_PAGE_MASK << 1));
> #if defined(TARGET_MIPS64)
> env->CP0_EntryHi &= env->SEGMask;
> - env->CP0_XContext = (env->CP0_XContext & ((~0ULL) << (env->SEGBITS -
> 7))) |
> - ((address & 0xC00000000000ULL) >> (55 -
> env->SEGBITS)) |
> - ((address & ((1ULL << env->SEGBITS) - 1) &
> 0xFFFFFFFFFFFFE000ULL) >> 9);
> + env->CP0_XContext =
> + /* PTEBase */ (env->CP0_XContext & ((~0ULL) << (env->SEGBITS -
> 7))) |
> + /* R */ (extract64(address, 62, 2) << (env->SEGBITS - 9)) |
> + /* BadVPN2 */ (extract64(address, 13, env->SEGBITS - 13) << 4);
> #endif
> cs->exception_index = exception;
> env->error_code = error_code;
> --
> 1.7.1
>
>
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