Re: [PATCH 4/8] 8xx: Fixup DAR from buggy dcbX instructions.
From: Scott Wood <hidden>
Date: 2009-10-14 17:19:41
On Sun, Oct 11, 2009 at 06:35:08PM +0200, Joakim Tjernlund wrote:
quoted hunk ↗ jump to hunk
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). --- arch/powerpc/kernel/head_8xx.S | 146 +++++++++++++++++++++++++++++++++++++++- 1 files changed, 145 insertions(+), 1 deletions(-)diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 093176c..9839e79 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S@@ -494,7 +494,8 @@ DataTLBError: mfspr r10, SPRN_DAR cmpwi cr0, r10, 0x00f0 - beq- 2f /* must be a buggy dcbX, icbi insn. */ + beq- FixDAR /* must be a buggy dcbX, icbi insn. */ +DARFix: /* Return from dcbx instruction bug workaround, r10 holds value of DAR */
Both FixDAR and DARFix? Could we make the labels a little clearer?
+/* 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. + */
How often does this happen? Could we just do it in C code after saving all the registers, and avoid the self modifying stuff (or the big switch statement equivalent)? -Scott