[Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu exception

[Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu exception

[Yongbok Kim]

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.
Also fixed the below line which overs 80 characters.

Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
---
 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

Re: [Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu exception

[James Hogan]

[-- Attachment #1: Type: text/plain, Size: 1884 bytes --]

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 <yongbok.kim@imgtec.com>

Reviewed-by: James Hogan <james.hogan@imgtec.com>

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
> 
> 

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

Re: [Qemu-devel] [PATCH v4] target-mips: fix updating XContext on mmu exception

[Leon Alrae]

On 29/10/15 17:17, 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.
> Also fixed the below line which overs 80 characters.
> 
> Signed-off-by: Yongbok Kim <yongbok.kim@imgtec.com>
> ---
>  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;
> 

Thanks for cleaning up the XContext calculation. I applied this one as
well as SIGRIE and RDHWR patches to the target-mips queue.

Regards,
Leon