[PATCH 4/9] 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 <[EMAIL PROTECTED]> --- arch/powerpc/kernel/head_8xx.S |6 ++ 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 e40e122..dd223df 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -301,6 +301,12 @@ InstructionTLBMiss: stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_SRR0 /* Get effective address of fault */ +#ifdef CONFIG_8xx_CPU15 + addir11, r10, 0x1000 + tlbie r11 + addir11, 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 8ecd01a..322b155 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 -- 1.5.3 ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
[PATCH 4/9] 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 <[EMAIL PROTECTED]> --- arch/powerpc/kernel/head_8xx.S |6 ++ 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 e40e122..dd223df 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -301,6 +301,12 @@ InstructionTLBMiss: stw r10, 0(r0) stw r11, 4(r0) mfspr r10, SPRN_SRR0 /* Get effective address of fault */ +#ifdef CONFIG_8xx_CPU15 + addir11, r10, 0x1000 + tlbie r11 + addir11, 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 39bb8c5..b8dd515 100644 --- a/arch/powerpc/platforms/8xx/Kconfig +++ b/arch/powerpc/platforms/8xx/Kconfig @@ -99,6 +99,22 @@ 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 -- 1.5.0.3 ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
