On 2 November 2015 at 18:14, Mark Rutland <mark.rutl...@arm.com> wrote: > The ARM architecture requires a DSB to complete TLB maintenance, with a > subsequent ISB being required to synchronize subsequent items in the > current instruction stream against the completed TLB maintenance. > > The ArmEnableMmu function is currently missing the DSB, and hence the > TLB maintenance is not guaranteed to have completed at the point the MMU > is enabled. This may result in unpredictable behaviour. > > The DSB subsequent to the write to SCTLR_EL1 is unnecessary; the ISB > alone is sufficient to complete all prior instructions and to > synchronise the new context with any subsequent instructions. > > This patch adds missing DSBs to complete TLB maintenance, and removes > the unnecessary trailing DSB. > > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Mark Rutland <mark.rutl...@arm.com> > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > Cc: Laszlo Ersek <ler...@redhat.com> > Cc: Leif Lindholm <leif.lindh...@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheu...@linaro.org> Thanks. I will add this to my cache maintenance series. Note that this is ArmPkg not ArmVirtPkg, but I will fix that up before resending -- Ard. > --- > ArmPkg/Library/ArmLib/AArch64/AArch64Support.S | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S > b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S > index bdede48..28cf27f 100644 > --- a/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S > +++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Support.S > @@ -123,18 +123,20 @@ ASM_PFX(ArmEnableMmu): > 4: orr x0, x0, #CTRL_M_BIT // Set MMU enable bit > EL1_OR_EL2_OR_EL3(x1) > 1: tlbi vmalle1 > + dsb nsh > isb > msr sctlr_el1, x0 // Write back > b 4f > 2: tlbi alle2 > + dsb nsh > isb > msr sctlr_el2, x0 // Write back > b 4f > 3: tlbi alle3 > + dsb nsh > isb > msr sctlr_el3, x0 // Write back > -4: dsb sy > - isb > +4: isb > ret > > > -- > 1.9.1 > _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
