[PATCH] powerpc: Fix __flush_icache_range on 44x

Josh Boyer jwboyer at linux.vnet.ibm.com
Mon Aug 17 23:41:36 EST 2009

The ptrace POKETEXT interface allows a process to modify the text pages of
a child process being ptraced, usually to insert breakpoints via trap
instructions.  The kernel eventually calls copy_to_user_page, which in turn
calls __flush_icache_range to invalidate the icache lines for the child

However, this function does not work on 44x due to the icache being virtually
indexed.  This was noticed by a breakpoint being triggered after it had been
cleared by ltrace on a 440EPx board.  The convenient solution is to do a
flash invalidate of the icache in the __flush_icache_range function.

Signed-off-by: Josh Boyer <jwboyer at linux.vnet.ibm.com>


diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 15f28e0..c9805a4 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
 2:	icbi	0,r6
 	addi	r6,r6,L1_CACHE_BYTES
 	bdnz	2b
+#ifdef CONFIG_44x
+	iccci	r0, r0
 	sync				/* additional sync needed on g4 */

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