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 <jwbo...@linux.vnet.ibm.com>
---
I tested this on powerpc-next this morning using the same testcase as before.
diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index 15f28e0..da9c0c4 100644
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -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
blr
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
