powerpc/8xx: drop unused self-modifying code alternative to FixupDAR.

The code which fixups the DAR on TLB errors for dbcX instructions
has a self-modifying code alternative that has never been used.

Drop it.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b095e12c82fcba1ac4c09fc3b85d969f36614746.1566417610.git.christophe.leroy@c-s.fr

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5ab9178..5db461d 100644 (file)
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -574,8 +574,6 @@ InstructionBreakpoint:
  * by decoding the registers used by the dcbx instruction and adding them.
  * DAR is set to the calculated address.
  */
- /* define if you don't want to use self modifying code */
-#define NO_SELF_MODIFYING_CODE
 FixupDAR:/* Entry point for dcbx workaround. */
        mtspr   SPRN_M_TW, r10
        /* fetch instruction from memory. */
@@ -639,27 +637,6 @@ FixupDAR:/* Entry point for dcbx workaround. */
        rlwinm  r10, r10,0,7,5  /* Clear store bit for buggy dcbst insn */
        mtspr   SPRN_DSISR, r10
 142:   /* continue, it was a dcbx, dcbi instruction. */
-#ifndef NO_SELF_MODIFYING_CODE
-       andis.  r10,r11,0x1f    /* test if reg RA is r0 */
-       li      r10,modified_instr@l
-       dcbtst  r0,r10          /* touch for store */
-       rlwinm  r11,r11,0,0,20  /* Zero lower 10 bits */
-       oris    r11,r11,640     /* Transform instr. to a "add r10,RA,RB" */
-       ori     r11,r11,532
-       stw     r11,0(r10)      /* store add/and instruction */
-       dcbf    0,r10           /* flush new instr. to memory. */
-       icbi    0,r10           /* invalidate instr. cache line */
-       mfspr   r11, SPRN_SPRG_SCRATCH1 /* restore r11 */
-       mfspr   r10, SPRN_SPRG_SCRATCH0 /* restore r10 */
-       isync                   /* Wait until new instr is loaded from memory */
-modified_instr:
-       .space  4               /* this is where the add instr. is stored */
-       bne+    143f
-       subf    r10,r0,r10      /* r10=r10-r0, only if reg RA is r0 */
-143:   mtdar   r10             /* store faulting EA in DAR */
-       mfspr   r10,SPRN_M_TW
-       b       DARFixed        /* Go back to normal TLB handling */
-#else
        mfctr   r10
        mtdar   r10                     /* save ctr reg in DAR */
        rlwinm  r10, r11, 24, 24, 28    /* offset into jump table for reg RB */
@@ -723,7 +700,6 @@ modified_instr:
        add     r10, r10, r11   /* add it */
        mfctr   r11             /* restore r11 */
        b       151b
-#endif
 
 /*
  * This is where the main kernel code starts.