This is an assembler version to fixup DAR not being set
by dcbX, icbi instructions. There are two versions, one
uses selfmodifing code, the other uses a
jump table but is much bigger(default).
Signed-off-by: Joakim Tjernlund <joakim.tjernl...@transmode.se>
---
arch/ppc/kernel/head_8xx.S | 149 +++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 146 insertions(+), 3 deletions(-)
diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S
index 48e9dde..f4c3f41 100644
--- a/arch/ppc/kernel/head_8xx.S
+++ b/arch/ppc/kernel/head_8xx.S
@@ -511,8 +511,17 @@ DataTLBError:
stw r20, 0(r0)
stw r21, 4(r0)
- mfspr r20, DSISR
- andis. r21, r20, 0x4800 /* !translation or protection */
+ mfspr r20, DAR
+ cmpwi cr0, r20, 0x00f0
+ beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
+DARFixed:
+ /* As the DAR fixup may clear store we may have all 3 states zero.
+ * Make sure only 0x0200(store) falls down into DIRTY handling
+ */
+ mfspr r21, DSISR
+ andis. r21, r21, 0x4a00 /* !translation, protection or store */
+ srwi r21, r21, 16
+ cmpwi cr0, r21, 0x0200 /* just store ? */
bne- 2f
/* Only Change bit left now, do it here as it is faster
* than trapping to the C fault handler.
@@ -534,7 +543,7 @@ DataTLBError:
* are initialized in mapin_ram(). This will avoid the problem,
* assuming we only use the dcbi instruction on kernel addresses.
*/
- mfspr r20, DAR
+ /* DAR is in r20 already */
rlwinm r21, r20, 0, 0, 19
ori r21, r21, MD_EVALID
mfspr r20, M_CASID
@@ -618,6 +627,140 @@ DataTLBError:
STD_EXCEPTION(0x1f00, Trap_1f, UnknownException)
. = 0x2000
+/* This is the procedure to calculate the data EA for buggy dcbx,dcbi
instructions
+ * by decoding the registers used by the dcbx instruction and adding them.
+ * DAR is set to the calculated address and r10 also holds the EA on exit.
+ */
+ /* define if you don't want to use self modifying code */
+#define NO_SELF_MODIFYING_CODE
+FixupDAR:/* Entry point for dcbx workaround. */
+ /* fetch instruction from memory. */
+ mfspr r20, SRR0
+ andis. r21, r20, 0x8000 /* Address >= 0x80000000 */
+ DO_8xx_CPU6(0x3780, r3)
+ mtspr MD_EPN, r20
+ mfspr r21, M_TWB /* Get level 1 table entry address */
+ beq- 3f /* Branch if user space */
+ lis r21, (swapper_pg_dir-PAGE_OFFSET)@h
+ ori r21, r21, (swapper_pg_dir-PAGE_OFFSET)@l
+ rlwimi r21, r20, 32-20, 0xffc /* r21 = r21&~0xffc|(r20>>20)&0xffc */
+3: lwz r21, 0(r21) /* Get the level 1 entry */
+ tophys (r21, r21)
+ DO_8xx_CPU6(0x3b80, r3)
+ mtspr MD_TWC, r21 /* Load pte table base address */
+ mfspr r21, MD_TWC /* ....and get the pte address */
+ lwz r21, 0(r21) /* Get the pte */
+ /* concat physical page address(r21) and page offset(r20) */
+ rlwimi r21, r20, 0, 20, 31
+ lwz r21,0(r21)
+/* Check if it really is a dcbx instruction. */
+/* dcbt and dcbtst does not generate DTLB Misses/Errors,
+ * no need to include them here */
+ srwi r20, r21, 26 /* check if major OP code is 31 */
+ cmpwi cr0, r20, 31
+ bne- 141f
+ rlwinm r20, r21, 0, 21, 30
+ cmpwi cr0, r20, 2028 /* Is dcbz? */
+ beq+ 142f
+ cmpwi cr0, r20, 940 /* Is dcbi? */
+ beq+ 142f
+ cmpwi cr0, r20, 108 /* Is dcbst? */
+ beq+ 144f /* Fix up store bit! */
+ cmpwi cr0, r20, 172 /* Is dcbf? */
+ beq+ 142f
+ cmpwi cr0, r20, 1964 /* Is icbi? */
+ beq+ 142f
+141: mfspr r20, DAR /* r20 must hold DAR at exit */
+ b DARFixed /* Nope, go back to normal TLB processing */
+
+144: mfspr r20, DSISR
+ rlwinm r20, r20,0,7,5 /* Clear store bit for buggy dcbst insn */
+ mtspr DSISR, r20
+142: /* continue, it was a dcbx, dcbi instruction. */
+#ifdef CONFIG_8xx_CPU6
+ lwz r3, 8(r0) /* restore r3 from memory */
+#endif
+#ifndef NO_SELF_MODIFYING_CODE
+ andis. r20,r21,0x1f /* test if reg RA is r0 */
+ li r20,modified_instr@l
+ dcbtst r0,r20 /* touch for store */
+ rlwinm r21,r21,0,0,20 /* Zero lower 10 bits */
+ oris r21,r21,640 /* Transform instr. to a "add r20,RA,RB" */
+ ori r21,r21,532
+ stw r21,0(r20) /* store add/and instruction */
+ dcbf 0,r20 /* flush new instr. to memory. */
+ icbi 0,r20 /* invalidate instr. cache line */
+ lwz r21, 4(r0) /* restore r21 from memory */
+ mfspr r20, M_TW /* restore r20 from M_TW */
+ isync /* Wait until new instr is loaded from memory */
+modified_instr:
+ .space 4 /* this is where the add instr. is stored */
+ bne+ 143f
+ subf r20,r0,r20 /* r20=r20-r0, only if reg RA is r0 */
+143: mtdar r20 /* store faulting EA in DAR */
+ b DARFixed /* Go back to normal TLB handling */
+#else
+ mfctr r20
+ mtdar r20 /* save ctr reg in DAR */
+ rlwinm r20, r21, 24, 24, 28 /* offset into jump table for reg RB */
+ addi r20, r20, 150f@l /* add start of table */
+ mtctr r20 /* load ctr with jump address */
+ xor r20, r20, r20 /* sum starts at zero */
+ bctr /* jump into table */
+150:
+ add r20, r20, r0 ;b 151f
+ add r20, r20, r1 ;b 151f
+ add r20, r20, r2 ;b 151f
+ add r20, r20, r3 ;b 151f
+ add r20, r20, r4 ;b 151f
+ add r20, r20, r5 ;b 151f
+ add r20, r20, r6 ;b 151f
+ add r20, r20, r7 ;b 151f
+ add r20, r20, r8 ;b 151f
+ add r20, r20, r9 ;b 151f
+ add r20, r20, r10 ;b 151f
+ add r20, r20, r11 ;b 151f
+ add r20, r20, r12 ;b 151f
+ add r20, r20, r13 ;b 151f
+ add r20, r20, r14 ;b 151f
+ add r20, r20, r15 ;b 151f
+ add r20, r20, r16 ;b 151f
+ add r20, r20, r17 ;b 151f
+ add r20, r20, r18 ;b 151f
+ add r20, r20, r19 ;b 151f
+ mtctr r21 ;b 154f /* r20 needs special handling */
+ mtctr r21 ;b 153f /* r21 needs special handling */
+ add r20, r20, r22 ;b 151f
+ add r20, r20, r23 ;b 151f
+ add r20, r20, r24 ;b 151f
+ add r20, r20, r25 ;b 151f
+ add r20, r20, r26 ;b 151f
+ add r20, r20, r27 ;b 151f
+ add r20, r20, r28 ;b 151f
+ add r20, r20, r29 ;b 151f
+ add r20, r20, r30 ;b 151f
+ add r20, r20, r31
+151:
+ rlwinm. r21,r21,19,24,28 /* offset into jump table for reg RA */
+ beq 152f /* if reg RA is zero, don't add it */
+ addi r21, r21, 150b@l /* add start of table */
+ mtctr r21 /* load ctr with jump address */
+ rlwinm r21,r21,0,16,10 /* make sure we don't execute this more
than once */
+ bctr /* jump into table */
+152:
+ mfdar r21
+ mtctr r21 /* restore ctr reg from DAR */
+ mtdar r20 /* save fault EA to DAR */
+ b DARFixed /* Go back to normal TLB handling */
+
+ /* special handling for r20,r21 since these are modified already */
+153: lwz r21, 4(r0) /* load r21 from memory */
+ b 155f
+154: mfspr r21, M_TW /* load r20 from M_TW */
+155: add r20, r20, r21 /* add it */
+ mfctr r21 /* restore r21 */
+ b 151b
+#endif
/*
* This code finishes saving the registers to the exception frame
--
1.7.3.4
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