arch/ppc64/mm/hash_low.S

   1 /*
   2  * ppc64 MMU hashtable management routines
   3  *
   4  * (c) Copyright IBM Corp. 2003
   5  *
   6  * Maintained by: Benjamin Herrenschmidt
   7  *                <benh@kernel.crashing.org>
   8  *
   9  * This file is covered by the GNU Public Licence v2 as
  10  * described in the kernel's COPYING file.
  11  */
  12
  13 #include <asm/processor.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/mmu.h>
  16 #include <asm/page.h>
  17 #include <asm/types.h>
  18 #include <asm/ppc_asm.h>
  19 #include <asm/offsets.h>
  20 #include <asm/cputable.h>
  21
  22         .text
  23
  24 /*
  25  * Stackframe:
  26  *
  27  *         +-> Back chain                       (SP + 256)
  28  *         |   General register save area       (SP + 112)
  29  *         |   Parameter save area              (SP + 48)
  30  *         |   TOC save area                    (SP + 40)
  31  *         |   link editor doubleword           (SP + 32)
  32  *         |   compiler doubleword              (SP + 24)
  33  *         |   LR save area                     (SP + 16)
  34  *         |   CR save area                     (SP + 8)
  35  * SP ---> +-- Back chain                       (SP + 0)
  36  */
  37 #define STACKFRAMESIZE  256
  38
  39 /* Save parameters offsets */
  40 #define STK_PARM(i)     (STACKFRAMESIZE + 48 + ((i)-3)*8)
  41
  42 /* Save non-volatile offsets */
  43 #define STK_REG(i)      (112 + ((i)-14)*8)
  44
  45 /*
  46  * _hash_page(unsigned long ea, unsigned long access, unsigned long vsid,
  47  *              pte_t *ptep, unsigned long trap, int local)
  48  *
  49  * Adds a page to the hash table. This is the non-LPAR version for now
  50  */
  51
  52 _GLOBAL(__hash_page)
  53         mflr    r0
  54         std     r0,16(r1)
  55         stdu    r1,-STACKFRAMESIZE(r1)
  56         /* Save all params that we need after a function call */
  57         std     r6,STK_PARM(r6)(r1)
  58         std     r8,STK_PARM(r8)(r1)
  59
  60         /* Add _PAGE_PRESENT to access */
  61         ori     r4,r4,_PAGE_PRESENT
  62
  63         /* Save non-volatile registers.
  64          * r31 will hold "old PTE"
  65          * r30 is "new PTE"
  66          * r29 is "va"
  67          * r28 is a hash value
  68          * r27 is hashtab mask (maybe dynamic patched instead ?)
  69          */
  70         std     r27,STK_REG(r27)(r1)
  71         std     r28,STK_REG(r28)(r1)
  72         std     r29,STK_REG(r29)(r1)
  73         std     r30,STK_REG(r30)(r1)
  74         std     r31,STK_REG(r31)(r1)
  75
  76         /* Step 1:
  77          *
  78          * Check permissions, atomically mark the linux PTE busy
  79          * and hashed.
  80          */
  81 1:
  82         ldarx   r31,0,r6
  83         /* Check access rights (access & ~(pte_val(*ptep))) */
  84         andc.   r0,r4,r31
  85         bne-    htab_wrong_access
  86         /* Check if PTE is busy */
  87         andi.   r0,r31,_PAGE_BUSY
  88         /* If so, just bail out and refault if needed. Someone else
  89          * is changing this PTE anyway and might hash it.
  90          */
  91         bne-    bail_ok
  92         /* Prepare new PTE value (turn access RW into DIRTY, then
  93          * add BUSY,HASHPTE and ACCESSED)
  94          */
  95         rlwinm  r30,r4,32-9+7,31-7,31-7 /* _PAGE_RW -> _PAGE_DIRTY */
  96         or      r30,r30,r31
  97         ori     r30,r30,_PAGE_BUSY | _PAGE_ACCESSED | _PAGE_HASHPTE
  98         /* Write the linux PTE atomically (setting busy) */
  99         stdcx.  r30,0,r6
 100         bne-    1b
 101         isync
 102
 103         /* Step 2:
 104          *
 105          * Insert/Update the HPTE in the hash table. At this point,
 106          * r4 (access) is re-useable, we use it for the new HPTE flags
 107          */
 108
 109         /* Calc va and put it in r29 */
 110         rldicr  r29,r5,28,63-28
 111         rldicl  r3,r3,0,36
 112         or      r29,r3,r29
 113
 114         /* Calculate hash value for primary slot and store it in r28 */
 115         rldicl  r5,r5,0,25              /* vsid & 0x0000007fffffffff */
 116         rldicl  r0,r3,64-12,48          /* (ea >> 12) & 0xffff */
 117         xor     r28,r5,r0
 118
 119         /* Convert linux PTE bits into HW equivalents */
 120         andi.   r3,r30,0x1fe            /* Get basic set of flags */
 121         xori    r3,r3,HW_NO_EXEC        /* _PAGE_EXEC -> NOEXEC */
 122         rlwinm  r0,r30,32-9+1,30,30     /* _PAGE_RW -> _PAGE_USER (r0) */
 123         rlwinm  r4,r30,32-7+1,30,30     /* _PAGE_DIRTY -> _PAGE_USER (r4) */
 124         and     r0,r0,r4                /* _PAGE_RW & _PAGE_DIRTY -> r0 bit 30 */
 125         andc    r0,r30,r0               /* r0 = pte & ~r0 */
 126         rlwimi  r3,r0,32-1,31,31        /* Insert result into PP lsb */
 127
 128         /* We eventually do the icache sync here (maybe inline that
 129          * code rather than call a C function...)
 130          */
 131 BEGIN_FTR_SECTION
 132 BEGIN_FTR_SECTION
 133         mr      r4,r30
 134         mr      r5,r7
 135         bl      .hash_page_do_lazy_icache
 136 END_FTR_SECTION_IFSET(CPU_FTR_NOEXECUTE)
 137 END_FTR_SECTION_IFCLR(CPU_FTR_COHERENT_ICACHE)
 138
 139         /* At this point, r3 contains new PP bits, save them in
 140          * place of "access" in the param area (sic)
 141          */
 142         std     r3,STK_PARM(r4)(r1)
 143
 144         /* Get htab_hash_mask */
 145         ld      r4,htab_hash_mask@got(2)
 146         ld      r27,0(r4)       /* htab_hash_mask -> r27 */
 147
 148         /* Check if we may already be in the hashtable, in this case, we
 149          * go to out-of-line code to try to modify the HPTE
 150          */
 151         andi.   r0,r31,_PAGE_HASHPTE
 152         bne     htab_modify_pte
 153
 154 htab_insert_pte:
 155         /* Clear hpte bits in new pte (we also clear BUSY btw) and
 156          * add _PAGE_HASHPTE
 157          */
 158         lis     r0,_PAGE_HPTEFLAGS@h
 159         ori     r0,r0,_PAGE_HPTEFLAGS@l
 160         andc    r30,r30,r0
 161         ori     r30,r30,_PAGE_HASHPTE
 162
 163         /* page number in r5 */
 164         rldicl  r5,r31,64-PTE_SHIFT,PTE_SHIFT
 165
 166         /* Calculate primary group hash */
 167         and     r0,r28,r27
 168         rldicr  r3,r0,3,63-3    /* r0 = (hash & mask) << 3 */
 169
 170         /* Call ppc_md.hpte_insert */
 171         ld      r7,STK_PARM(r4)(r1)     /* Retreive new pp bits */
 172         mr      r4,r29                  /* Retreive va */
 173         li      r6,0                    /* no vflags */
 174 _GLOBAL(htab_call_hpte_insert1)
 175         bl      .                       /* Will be patched by htab_finish_init() */
 176         cmpdi   0,r3,0
 177         bge     htab_pte_insert_ok      /* Insertion successful */
 178         cmpdi   0,r3,-2                 /* Critical failure */
 179         beq-    htab_pte_insert_failure
 180
 181         /* Now try secondary slot */
 182
 183         /* page number in r5 */
 184         rldicl  r5,r31,64-PTE_SHIFT,PTE_SHIFT
 185
 186         /* Calculate secondary group hash */
 187         andc    r0,r27,r28
 188         rldicr  r3,r0,3,63-3    /* r0 = (~hash & mask) << 3 */
 189
 190         /* Call ppc_md.hpte_insert */
 191         ld      r7,STK_PARM(r4)(r1)     /* Retreive new pp bits */
 192         mr      r4,r29                  /* Retreive va */
 193         li      r6,HPTE_V_SECONDARY@l   /* secondary slot */
 194 _GLOBAL(htab_call_hpte_insert2)
 195         bl      .                       /* Will be patched by htab_finish_init() */
 196         cmpdi   0,r3,0
 197         bge+    htab_pte_insert_ok      /* Insertion successful */
 198         cmpdi   0,r3,-2                 /* Critical failure */
 199         beq-    htab_pte_insert_failure
 200
 201         /* Both are full, we need to evict something */
 202         mftb    r0
 203         /* Pick a random group based on TB */
 204         andi.   r0,r0,1
 205         mr      r5,r28
 206         bne     2f
 207         not     r5,r5
 208 2:      and     r0,r5,r27
 209         rldicr  r3,r0,3,63-3    /* r0 = (hash & mask) << 3 */
 210         /* Call ppc_md.hpte_remove */
 211 _GLOBAL(htab_call_hpte_remove)
 212         bl      .                       /* Will be patched by htab_finish_init() */
 213
 214         /* Try all again */
 215         b       htab_insert_pte
 216
 217 bail_ok:
 218         li      r3,0
 219         b       bail
 220
 221 htab_pte_insert_ok:
 222         /* Insert slot number & secondary bit in PTE */
 223         rldimi  r30,r3,12,63-15
 224
 225         /* Write out the PTE with a normal write
 226          * (maybe add eieio may be good still ?)
 227          */
 228 htab_write_out_pte:
 229         ld      r6,STK_PARM(r6)(r1)
 230         std     r30,0(r6)
 231         li      r3, 0
 232 bail:
 233         ld      r27,STK_REG(r27)(r1)
 234         ld      r28,STK_REG(r28)(r1)
 235         ld      r29,STK_REG(r29)(r1)
 236         ld      r30,STK_REG(r30)(r1)
 237         ld      r31,STK_REG(r31)(r1)
 238         addi    r1,r1,STACKFRAMESIZE
 239         ld      r0,16(r1)
 240         mtlr    r0
 241         blr
 242
 243 htab_modify_pte:
 244         /* Keep PP bits in r4 and slot idx from the PTE around in r3 */
 245         mr      r4,r3
 246         rlwinm  r3,r31,32-12,29,31
 247
 248         /* Secondary group ? if yes, get a inverted hash value */
 249         mr      r5,r28
 250         andi.   r0,r31,_PAGE_SECONDARY
 251         beq     1f
 252         not     r5,r5
 253 1:
 254         /* Calculate proper slot value for ppc_md.hpte_updatepp */
 255         and     r0,r5,r27
 256         rldicr  r0,r0,3,63-3    /* r0 = (hash & mask) << 3 */
 257         add     r3,r0,r3        /* add slot idx */
 258
 259         /* Call ppc_md.hpte_updatepp */
 260         mr      r5,r29                  /* va */
 261         li      r6,0                    /* large is 0 */
 262         ld      r7,STK_PARM(r8)(r1)     /* get "local" param */
 263 _GLOBAL(htab_call_hpte_updatepp)
 264         bl      .                       /* Will be patched by htab_finish_init() */
 265
 266         /* if we failed because typically the HPTE wasn't really here
 267          * we try an insertion.
 268          */
 269         cmpdi   0,r3,-1
 270         beq-    htab_insert_pte
 271
 272         /* Clear the BUSY bit and Write out the PTE */
 273         li      r0,_PAGE_BUSY
 274         andc    r30,r30,r0
 275         b       htab_write_out_pte
 276
 277 htab_wrong_access:
 278         /* Bail out clearing reservation */
 279         stdcx.  r31,0,r6
 280         li      r3,1
 281         b       bail
 282
 283 htab_pte_insert_failure:
 284         /* Bail out restoring old PTE */
 285         ld      r6,STK_PARM(r6)(r1)
 286         std     r31,0(r6)
 287         li      r3,-1
 288         b       bail
 289
 290