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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-10-31 01:42:19 -0400
committerJosh Boyer <jwboyer@linux.vnet.ibm.com>2007-11-01 08:15:30 -0400
commitb98ac05d5e460301fbea24cceed0f2a601c82e22 (patch)
tree2e556ad28a007d13339300fbbd4942d0ec9f023c /arch/ppc/mm
parente701d269aa28996f3502780951fe1b12d5d66b49 (diff)
[POWERPC] 4xx: Deal with 44x virtually tagged icache
The 44x family has an interesting "feature" which is a virtually tagged instruction cache (yuck !). So far, we haven't dealt with it properly, which means we've been mostly lucky or people didn't report the problems, unless people have been running custom patches in their distro... This is an attempt at fixing it properly. I chose to do it by setting a global flag whenever we change a PTE that was previously marked executable, and flush the entire instruction cache upon return to user space when that happens. This is a bit heavy handed, but it's hard to do more fine grained flushes as the icbi instruction, on those processor, for some very strange reasons (since the cache is virtually mapped) still requires a valid TLB entry for reading in the target address space, which isn't something I want to deal with. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Diffstat (limited to 'arch/ppc/mm')
-rw-r--r--arch/ppc/mm/44x_mmu.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/ppc/mm/44x_mmu.c b/arch/ppc/mm/44x_mmu.c
index 0a0a0487b334..6536a25cfcb8 100644
--- a/arch/ppc/mm/44x_mmu.c
+++ b/arch/ppc/mm/44x_mmu.c
@@ -61,6 +61,7 @@ extern char etext[], _stext[];
61 */ 61 */
62unsigned int tlb_44x_index = 0; 62unsigned int tlb_44x_index = 0;
63unsigned int tlb_44x_hwater = 62; 63unsigned int tlb_44x_hwater = 62;
64int icache_44x_need_flush;
64 65
65/* 66/*
66 * "Pins" a 256MB TLB entry in AS0 for kernel lowmem 67 * "Pins" a 256MB TLB entry in AS0 for kernel lowmem