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powerpc: Fix __flush_icache_range on 44x 

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
process.

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@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Josh Boyer 2009-08-19 04:27:53 +00:00 committed by Benjamin Herrenschmidt
parent ea3cc330ac
commit 14d757520a
1 changed files with 7 additions and 0 deletions
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7
arch/powerpc/kernel/misc_32.S
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@ -342,10 +342,17 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
addi r3,r3,L1_CACHE_BYTES
bdnz 1b
sync /* wait for dcbst's to get to ram */
#ifndef CONFIG_44x
mtctr r4
2: icbi 0,r6
addi r6,r6,L1_CACHE_BYTES
bdnz 2b
#else
/* Flash invalidate on 44x because we are passed kmapped addresses and
this doesn't work for userspace pages due to the virtually tagged
icache. Sigh. */
iccci 0, r0
#endif
sync /* additional sync needed on g4 */
isync
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