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authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2007-10-31 16:42:19 +1100
committerJosh Boyer <jwboyer@linux.vnet.ibm.com>2007-11-01 07:15:30 -0500
commitb98ac05d5e460301fbea24cceed0f2a601c82e22 (patch)
tree2e556ad28a007d13339300fbbd4942d0ec9f023c /arch/powerpc/kernel
parent[POWERPC] 4xx: Fix 4xx flush_tlb_page() (diff)
downloadlinux-dev-b98ac05d5e460301fbea24cceed0f2a601c82e22.tar.xz
linux-dev-b98ac05d5e460301fbea24cceed0f2a601c82e22.zip
[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/powerpc/kernel')
-rw-r--r--arch/powerpc/kernel/entry_32.S23
-rw-r--r--arch/powerpc/kernel/misc_32.S9
2 files changed, 32 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 21d889e63e87..a7572cf464bd 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -244,6 +244,13 @@ syscall_exit_cont:
andis. r10,r0,DBCR0_IC@h
bnel- load_dbcr0
#endif
+#ifdef CONFIG_44x
+ lis r4,icache_44x_need_flush@ha
+ lwz r5,icache_44x_need_flush@l(r4)
+ cmplwi cr0,r5,0
+ bne- 2f
+1:
+#endif /* CONFIG_44x */
stwcx. r0,0,r1 /* to clear the reservation */
lwz r4,_LINK(r1)
lwz r5,_CCR(r1)
@@ -258,6 +265,12 @@ syscall_exit_cont:
mtspr SPRN_SRR1,r8
SYNC
RFI
+#ifdef CONFIG_44x
+2: li r7,0
+ iccci r0,r0
+ stw r7,icache_44x_need_flush@l(r4)
+ b 1b
+#endif /* CONFIG_44x */
66: li r3,-ENOSYS
b ret_from_syscall
@@ -683,6 +696,16 @@ resume_kernel:
/* interrupts are hard-disabled at this point */
restore:
+#ifdef CONFIG_44x
+ lis r4,icache_44x_need_flush@ha
+ lwz r5,icache_44x_need_flush@l(r4)
+ cmplwi cr0,r5,0
+ beq+ 1f
+ li r6,0
+ iccci r0,r0
+ stw r6,icache_44x_need_flush@l(r4)
+1:
+#endif /* CONFIG_44x */
lwz r0,GPR0(r1)
lwz r2,GPR2(r1)
REST_4GPRS(3, r1)
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 0ed2c7eddc9e..8b642ab26d37 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -543,12 +543,21 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
addi r3,r3,L1_CACHE_BYTES
bdnz 0b
sync
+#ifndef CONFIG_44x
+ /* We don't flush the icache on 44x. Those have a virtual icache
+ * and we don't have access to the virtual address here (it's
+ * not the page vaddr but where it's mapped in user space). The
+ * flushing of the icache on these is handled elsewhere, when
+ * a change in the address space occurs, before returning to
+ * user space
+ */
mtctr r4
1: icbi 0,r6
addi r6,r6,L1_CACHE_BYTES
bdnz 1b
sync
isync
+#endif /* CONFIG_44x */
blr
/*