On Tue, Nov 06, 2018 at 11:20:19AM -0500, David Long wrote:
> On 11/6/18 5:40 AM, Marc Zyngier wrote:
> >On Wed, 31 Oct 2018 13:56:58 +0000,
> >David Long <dave.long@xxxxxxxxxx> wrote:
> >>
> >>From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> >>
> >>Commit 10115105cb3aa17b5da1cb726ae8dd5f6854bd93 upstream.
> >>
> >>Add firmware based hardening for cores that require more complex
> >>handling in firmware.
> >>
> >>Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> >>Boot-tested-by: Tony Lindgren <tony@xxxxxxxxxxx>
> >>Reviewed-by: Tony Lindgren <tony@xxxxxxxxxxx>
> >>Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> >>Signed-off-by: David A. Long <dave.long@xxxxxxxxxx>
> >>---
> >> arch/arm/mm/proc-v7-bugs.c | 60 ++++++++++++++++++++++++++++++++++++++
> >> arch/arm/mm/proc-v7.S | 21 +++++++++++++
> >> 2 files changed, 81 insertions(+)
> >>
> >
> >[...]
> >
> >>diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> >>index 2d2e5ae85816..8fde9edb4a48 100644
> >>--- a/arch/arm/mm/proc-v7.S
> >>+++ b/arch/arm/mm/proc-v7.S
> >>@@ -9,6 +9,7 @@
> >> *
> >> * This is the "shell" of the ARMv7 processor support.
> >> */
> >>+#include <linux/arm-smccc.h>
> >> #include <linux/init.h>
> >> #include <linux/linkage.h>
> >> #include <asm/assembler.h>
> >>@@ -88,6 +89,26 @@ ENTRY(cpu_v7_dcache_clean_area)
> >> ret lr
> >> ENDPROC(cpu_v7_dcache_clean_area)
> >>+#ifdef CONFIG_ARM_PSCI
> >>+ .arch_extension sec
> >>+ENTRY(cpu_v7_smc_switch_mm)
> >>+ stmfd sp!, {r0 - r3}
> >>+ movw r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
> >>+ movt r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
> >>+ smc #0
> >>+ ldmfd sp!, {r0 - r3}
> >>+ b cpu_v7_switch_mm
> >>+ENDPROC(cpu_v7_smc_switch_mm)
> >>+ .arch_extension virt
> >>+ENTRY(cpu_v7_hvc_switch_mm)
> >>+ stmfd sp!, {r0 - r3}
> >>+ movw r0, #:lower16:ARM_SMCCC_ARCH_WORKAROUND_1
> >>+ movt r0, #:upper16:ARM_SMCCC_ARCH_WORKAROUND_1
> >>+ hvc #0
> >>+ ldmfd sp!, {r0 - r3}
> >>+ b cpu_v7_switch_mm
> >>+ENDPROC(cpu_v7_smc_switch_mm)
> >
> >As pointed out by Ard a while ago [1], this breaks Thumb-2 kernels.
> >Please keep this series on hold until this is fixed in mainline and
> >you can cherry-pick the corresponding patch.
> >
> >Thanks,
> >
> > M.
> >
> >[1] https://patchwork.kernel.org/patch/10475033/
> >
>
> Note that it looks like this problem is now in v4.14 stable too.
The good news is that Linus has just pulled the fix into mainline, so
we can now poke Greg to pick it up for all stable kernels - but, as a
result, we're going to get into a bit of a mess because it's going to
require careful management of which stable kernels, and getting it
applied by indirect reference along with _these_ patches.
I'm not sure if we've just made things easier or harder.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
