diff options
| author | Scott Wood <scottwood@freescale.com> | 2007-06-25 14:50:41 -0500 |
|---|---|---|
| committer | Kumar Gala <galak@kernel.crashing.org> | 2007-10-03 20:36:36 -0500 |
| commit | 7401685242fbcbf4b0660726372c77a88c4af17d (patch) | |
| tree | 71b814468d705c2c48184161c38a0295c832239d | |
| parent | 663edbd2640447dc43840568cd5701e6c9878d63 (diff) | |
[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 <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
| -rw-r--r-- | arch/powerpc/kernel/head_8xx.S | 6 | ||||
| -rw-r--r-- | arch/powerpc/platforms/8xx/Kconfig | 16 |
2 files changed, 22 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 9c30938aad5..f7458396cd7 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -298,6 +298,12 @@ InstructionTLBMiss: stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_SRR0 /* Get effective address of fault */ +#ifdef CONFIG_8xx_CPU15 + addi r11, r10, 0x1000 + tlbie r11 + addi r11, r10, -0x1000 + tlbie r11 +#endif DO_8xx_CPU6(0x3780, r3) mtspr SPRN_MD_EPN, r10 /* Have to use MD_EPN for walk, MI_EPN can't */ mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */ 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 |