From 7401685242fbcbf4b0660726372c77a88c4af17d Mon Sep 17 00:00:00 2001 From: Scott Wood Date: Mon, 25 Jun 2007 14:50:41 -0500 Subject: [POWERPC] 8xx: Work around CPU15 erratum. The CPU15 erratum on MPC8xx chips can cause incorrect code execution under certain circumstances, where there is a conditional or indirect branch in the last word of a page, with a target in the last cache line of the next page. This patch implements one of the suggested workarounds, by forcing a TLB miss whenever execution crosses a page boundary. This is done by invalidating the pages before and after the one being loaded into the TLB in the ITLB miss handler. Signed-off-by: Scott Wood Signed-off-by: Kumar Gala --- arch/powerpc/platforms/8xx/Kconfig | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'arch/powerpc/platforms/8xx') diff --git a/arch/powerpc/platforms/8xx/Kconfig b/arch/powerpc/platforms/8xx/Kconfig index 8ecd01ad0de..322b155f24e 100644 --- a/arch/powerpc/platforms/8xx/Kconfig +++ b/arch/powerpc/platforms/8xx/Kconfig @@ -100,6 +100,22 @@ config 8xx_CPU6 If in doubt, say N here. +config 8xx_CPU15 + bool "CPU15 Silicon Errata" + default y + help + This enables a workaround for erratum CPU15 on MPC8xx chips. + This bug can cause incorrect code execution under certain + circumstances. This workaround adds some overhead (a TLB miss + every time execution crosses a page boundary), and you may wish + to disable it if you have worked around the bug in the compiler + (by not placing conditional branches or branches to LR or CTR + in the last word of a page, with a target of the last cache + line in the next page), or if you have used some other + workaround. + + If in doubt, say Y here. + choice prompt "Microcode patch selection" default NO_UCODE_PATCH -- cgit v1.2.3