From: Mike Qiu <qiudayu@linux.vnet.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: paulus@samba.org, "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH] powerpc/mm: Fix hash computation function
Date: Wed, 30 Jan 2013 15:23:53 +0800 [thread overview]
Message-ID: <5108CA89.4080305@linux.vnet.ibm.com> (raw)
In-Reply-To: <1359524442-5861-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
With the fix, the machine can boot up successfully
Tested-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
于 2013/1/30 13:40, Aneesh Kumar K.V 写道:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> The ASM version of hash computation function was truncating the upper bit.
> Make the ASM version similar to hpt_hash function. Remove masking vsid bits.
> Without this patch, we observed hang during bootup due to not satisfying page
> fault request correctly. The fault handler used wrong hash values to update
> the HPTE. Hence we kept looping with page fault.
>
> hash_page(ea=000001003e260008, access=203, trap=300 ip=3fff91787134 dsisr 42000000
> The computed value of hash 000000000f22f390
> update: avpnv=4003e46054003e00, hash=000000000722f390, f=80000006, psize: 2 ...
>
> Reported-by: Mike Qiu <qiudayu@linux.vnet.ibm.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
> arch/powerpc/mm/hash_low_64.S | 62 +++++++++++++++++++++++------------------
> 1 file changed, 35 insertions(+), 27 deletions(-)
>
> diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
> index 5658508..7443481 100644
> --- a/arch/powerpc/mm/hash_low_64.S
> +++ b/arch/powerpc/mm/hash_low_64.S
> @@ -115,11 +115,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
> sldi r29,r5,SID_SHIFT - VPN_SHIFT
> rldicl r28,r3,64 - VPN_SHIFT,64 - (SID_SHIFT - VPN_SHIFT)
> or r29,r28,r29
> -
> - /* Calculate hash value for primary slot and store it in r28 */
> - rldicl r5,r5,0,25 /* vsid & 0x0000007fffffffff */
> - rldicl r0,r3,64-12,48 /* (ea >> 12) & 0xffff */
> - xor r28,r5,r0
> + /*
> + * Calculate hash value for primary slot and store it in r28
> + * r3 = va, r5 = vsid
> + * r0 = (va >> 12) & ((1ul << (28 - 12)) -1)
> + */
> + rldicl r0,r3,64-12,48
> + xor r28,r5,r0 /* hash */
> b 4f
>
> 3: /* Calc vpn and put it in r29 */
> @@ -130,11 +132,12 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
> /*
> * calculate hash value for primary slot and
> * store it in r28 for 1T segment
> + * r3 = va, r5 = vsid
> */
> - rldic r28,r5,25,25 /* (vsid << 25) & 0x7fffffffff */
> - clrldi r5,r5,40 /* vsid & 0xffffff */
> - rldicl r0,r3,64-12,36 /* (ea >> 12) & 0xfffffff */
> - xor r28,r28,r5
> + sldi r28,r5,25 /* vsid << 25 */
> + /* r0 = (va >> 12) & ((1ul << (40 - 12)) -1) */
> + rldicl r0,r3,64-12,36
> + xor r28,r28,r5 /* vsid ^ ( vsid << 25) */
> xor r28,r28,r0 /* hash */
>
> /* Convert linux PTE bits into HW equivalents */
> @@ -407,11 +410,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
> */
> rldicl r28,r3,64 - VPN_SHIFT,64 - (SID_SHIFT - VPN_SHIFT)
> or r29,r28,r29
> -
> - /* Calculate hash value for primary slot and store it in r28 */
> - rldicl r5,r5,0,25 /* vsid & 0x0000007fffffffff */
> - rldicl r0,r3,64-12,48 /* (ea >> 12) & 0xffff */
> - xor r28,r5,r0
> + /*
> + * Calculate hash value for primary slot and store it in r28
> + * r3 = va, r5 = vsid
> + * r0 = (va >> 12) & ((1ul << (28 - 12)) -1)
> + */
> + rldicl r0,r3,64-12,48
> + xor r28,r5,r0 /* hash */
> b 4f
>
> 3: /* Calc vpn and put it in r29 */
> @@ -426,11 +431,12 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
> /*
> * Calculate hash value for primary slot and
> * store it in r28 for 1T segment
> + * r3 = va, r5 = vsid
> */
> - rldic r28,r5,25,25 /* (vsid << 25) & 0x7fffffffff */
> - clrldi r5,r5,40 /* vsid & 0xffffff */
> - rldicl r0,r3,64-12,36 /* (ea >> 12) & 0xfffffff */
> - xor r28,r28,r5
> + sldi r28,r5,25 /* vsid << 25 */
> + /* r0 = (va >> 12) & ((1ul << (40 - 12)) -1) */
> + rldicl r0,r3,64-12,36
> + xor r28,r28,r5 /* vsid ^ ( vsid << 25) */
> xor r28,r28,r0 /* hash */
>
> /* Convert linux PTE bits into HW equivalents */
> @@ -752,25 +758,27 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
> rldicl r28,r3,64 - VPN_SHIFT,64 - (SID_SHIFT - VPN_SHIFT)
> or r29,r28,r29
>
> - /* Calculate hash value for primary slot and store it in r28 */
> - rldicl r5,r5,0,25 /* vsid & 0x0000007fffffffff */
> - rldicl r0,r3,64-16,52 /* (ea >> 16) & 0xfff */
> - xor r28,r5,r0
> + /* Calculate hash value for primary slot and store it in r28
> + * r3 = va, r5 = vsid
> + * r0 = (va >> 16) & ((1ul << (28 - 16)) -1)
> + */
> + rldicl r0,r3,64-16,52
> + xor r28,r5,r0 /* hash */
> b 4f
>
> 3: /* Calc vpn and put it in r29 */
> sldi r29,r5,SID_SHIFT_1T - VPN_SHIFT
> rldicl r28,r3,64 - VPN_SHIFT,64 - (SID_SHIFT_1T - VPN_SHIFT)
> or r29,r28,r29
> -
> /*
> * calculate hash value for primary slot and
> * store it in r28 for 1T segment
> + * r3 = va, r5 = vsid
> */
> - rldic r28,r5,25,25 /* (vsid << 25) & 0x7fffffffff */
> - clrldi r5,r5,40 /* vsid & 0xffffff */
> - rldicl r0,r3,64-16,40 /* (ea >> 16) & 0xffffff */
> - xor r28,r28,r5
> + sldi r28,r5,25 /* vsid << 25 */
> + /* r0 = (va >> 16) & ((1ul << (40 - 16)) -1) */
> + rldicl r0,r3,64-16,40
> + xor r28,r28,r5 /* vsid ^ ( vsid << 25) */
> xor r28,r28,r0 /* hash */
>
> /* Convert linux PTE bits into HW equivalents */
next prev parent reply other threads:[~2013-01-30 7:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-30 5:40 [PATCH] powerpc/mm: Fix hash computation function Aneesh Kumar K.V
2013-01-30 7:23 ` Mike Qiu [this message]
2013-02-04 3:29 ` Michael Ellerman
2013-02-04 4:24 ` Benjamin Herrenschmidt
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